Community Sodium Reduction: Is It Worth the Effort?

The role of salt in the pathogenesis of hypertension has been fired in the crucible of fierce debate amidst claims of industrial collusion and statistical manipulation. However, careful consideration of the evidence does provide us with some facts. In a cross-sectional observational study across 48 centers around the world, sodium excretion was significantly related to the upward slope of blood pressure with age but not to median or prevalence of blood pressure. This association was weakened somewhat when body mass index and alcohol intake were considered, but a possible role for dietary sodium intake and the rise in blood pressure with age was reported. The authors also estimated that a 100 mmol/day lower sodium intake would reduce on average blood pressure by 2.2 mm Hg systolic and 0.1 mm Hg diastolic, and suggested important public health benefits might result. Indeed, trials of treatment for hypertension would lend support to this contention with substantial reductions in stroke and cardiac events to be anticipated.

However, the results of a recent Cochrane review which collated more event data than previous reports suggested there is still insufficient evidence to exclude clinically important effects of reduced dietary salt on mortality or cardiovascular mortality in normotensive or hypertensive populations. This view has been challenged because of the inclusion of a study in heart failure: when excluded, the findings are positive. But there are reports of a harmful effect of sodium reduction on patients with heart failure and diabetes. So is there merit in advocating a community-based reduction in salt intake?

Graudal and colleagues have now performed a study in collaboration with the Nordic Cochrane Centre to estimate the effects of low vs. high sodium intake on blood pressure, renin, aldosterone, catecholamines, and lipids. One hundred and sixty seven studies were included. The effects on blood pressure were heterogeneous: in normotensive Caucasians blood pressure fell 1.3/0.05 mm Hg, in blacks 4/2 mm Hg, and Asians 1.3/1.7 mm Hg. The fall in systolic pressure in blacks was significant. In hypertensives the falls were more impressive: Caucasians 5.5/2.8, Blacks 6.4/2.4 and Asians 10.2/2.6. There were predictable rises in plasma, renin, aldosterone, catecholamines, and lipids.

Given that every community is going to comprise a mixture of ethnic backgrounds, hypertensive individuals, and some with premorbid conditions such as diabetes and heart failure, what should we do? Certainly dietary sodium reduction will have a beneficial effect by lowering blood pressure in those with the established disease, but there will be a need for this reduction to be quite substantial. Then it is probable that the achieved falls would be sufficient to reduce hypertension-associated risk regardless of the effects on the serum levels of renin, aldosterone, and catecholamines—which will be seen with thiazide diuretic use anyway. The issue then is whether whole communities will benefit. For the 70% who are normotensive, an intensive and sustained dietary change must be undertaken with a modest predicted lowering of blood pressure dependent upon ethnicity, and the possibility of some being harmed. It could be argued that the age-associated rise in pressure will be ameliorated but this is unproved. And were it to be so, over-the-counter sales of very low-dose thiazide diuretics might be preferred for pharmacist-screened individuals. A concerted campaign to reduce obesity and alcohol intake may be more rewarding and less risky.


Dietary Sodium Reduction in Heart Failure: A Challenge to the Cochrane Review

One of the conclusions of the study by Taylor et al., “Reduced Dietary Salt for the Prevention of Cardiovascular Disease: A Meta-Analysis of Randomized Controlled Trials (Cochrane Review)”, was that dietary that sodium reduction in heart failure (HF) is associated with cardiovascular morbidity and mortality. We question this conclusion which was based on a single HF study, that we assert is not sufficiently generalizable to be included in this analysis.

The study by Paterna et al. met the inclusion criteria for this Cochrane Review since it was a randomized trial of two levels of dietary sodium which evaluated cardiovascular morbidity and mortality over a 6 month period. They included 232 HF patients one month following hospitalization for decompensation. The intervention was 80 mmol (1.8 g) vs. 120 mmol (2.8 g) dietary sodium/day. Patients in both groups were prescribed 500–1000 mg of furosemide daily and a 1 l fluid restriction. Patients following the sodium-reduced diet had a greater risk of hospitalization and mortality. Patients in both groups developed hypotension, elevation in serum creatinine, and hypokalemia. Although dietary sodium was the only difference between the two study groups, we argue that other aspects of treatment likely confounded any clinical effects of dietary sodium.

HF is a sodium avid state, largely due to impaired renal sodium handling. Sodium balance in HF is maintained by an interplay of neurohumoral blockade which improves renal sodium handling, diuretics which directly increase natriuresis, and dietary sodium restriction. Although all patients in the study by Paterna et al. were taking angiotensin-converting enzyme inhibitors, only 9% were taking β-blockers. Furthermore, patients were prescribed very high doses of loop diuretics, which exceeded dosages typically used in clinical practice as well as maximum doses recommended by HF practice guidelines.3 The patients in the low sodium group were likely exposed to hypovolemia based on the combination of very high diuretic dosage, and both sodium and water restriction. This is likely based on the observations of low blood pressure and increased creatinine in this investigation. We therefore suggest that a more correct interpretation of Paterna et al. is that sodium restriction is dangerous in HF patient who are also receiving very high doses of loop diuretics and fluid restriction.

The results of the study by Paterna et al. have limited generalizability to broad HF populations who are on conventional dosages of diuretics, and are also receiving β-blocker therapy. In the absence of other randomized controlled trials, practice guidelines for HF should continue to encourage prudent sodium intake, and individualized and cautious use of diuretics to maintain euvolemia.

Source:American Journal of Hypertension


  • Taylor RS, Ashton KE, Moxham T, Hooper L, Ebrahim S. Reduced dietary salt for the prevention of cardiovascular disease: a meta-analysis of randomized controlled trials (cochrane review). Am J Hypertens 2011; 24:843–853
  • Paterna S, Gaspare P, Fasullo S, Sarullo FM, Di Pasquale P. Normal-sodium diet compared with low-sodium diet in compensated congestive heart failure: is sodium an old enemy or a new friend? Clin Sci 2008; 114:221–230.
  • Lindenfeld J, Albert NM, Boehmer JP, Collins SP, Ezekowitz JA, Givertz MM, Katz SD, Klapholz M, Moser DK, Rogers JG, Starling RC, Stevenson WG, Tang WH, Teerlink JR, Walsh MN; Heart Failure Society of America. HFSA 2010 Comprehensive Heart Failure Practice Guideline. J Card Fail 2010; 16:e1–194

Predictors of Postoperative Complications in Ulcerative Colitis

As in previous studies, patients were at increased risk for morbidity and mortality from colectomy surgery if they were older (age >64), required emergent surgery, or had at least two comorbidities.

Few population-based studies have been conducted on postoperative complications of colectomy in patients with ulcerative colitis (UC). One study involving >7000 patients in the U.S. reported that increased age, comorbidities, and emergent operations were risk factors for increased morbidity and mortality and that hospitals performing the highest volume of procedures had the lowest postoperative mortality rates . Now, investigators have used data from a population-based hospital system in Calgary, Canada, to explore predictors of postoperative complications among 666 patients who underwent colectomy for UC during a 13-year period.

During hospitalization for surgery, mortality was 1.5%, and 12.2% of patients developed postoperative infections. Risk factors for postoperative complications were age >64 (odds ratio, 2.0), emergent surgery (OR, 1.6), and presence of >2 comorbidities (OR, 1.9). For infectious complications, the risks associated with these factors increased (ORs, 2.9, 2.9, and 2.6, respectively), and male sex was also a risk factor (OR, 1.8). Undergoing emergent surgery >14 days after admission was associated with increased risk both for overall complications and for infections specifically (OR, 3 for both). Among patients who underwent emergent surgery, current smoking and presence of preoperative complications were each associated with a threefold increase in risk for serious postoperative complications (i.e., requiring procedural intervention or more-intense therapy).

Comment: This study confirms widely accepted principles for managing colectomy candidates with UC. Elders are at increased risk for complications. Patients with multiple comorbidities are also at increased risk, and medical management to optimize control of comorbidities is important. For patients admitted to the hospital for emergent care, medical management should be optimized early, and decisions to proceed with surgery should be made early when medical management fails. Immunosuppressants do not need to be avoided prior to colectomy, although previous studies have found that they increase risk for postoperative complications in elective UC surgery.

Source: Journal Watch Gastroenterology .


A Historic Day for Chimpanzees.

Making this historic day for animals even more significant, NIH has announced that it will accept all the recommendations of the IOM committee and that it will stop funding any new experiments on chimpanzees! All current experiments on chimpanzees will be reevaluated, and many may be ended. Until NIH conducts another review of the situation, none of the NIH-owned chimpanzees currently living in laboratories but not being experimented on will have to endure further experiments. This includes the chimpanzees at the Alamogordo facility.

We’ve been saying it for years. Today, the committee of scientists commissioned by the federal government to examine the scientific validity of experiments on chimpanzees publicly agreed with us. The long-awaited Institute of Medicine (IOM) report concludes: “[M]ost current biomedical research use of chimpanzees is not necessary.”

The report is the first step toward ending all experimentation on these remarkable animals. PETA’s statement, issued in response to the IOM’s ground-breaking report, says it all:

PETA welcomes the Institute of Medicine committee’s landmark report confirming that in the 21st century, the current use of chimpanzees—complex, intelligent, emotional individuals—in virtually every single area of testing, including HIV/AIDS, malaria, and the majority of hepatitis work, is scientifically and ethically indefensible.

These findings confirm what PETA has said for 30 years and what PETA communicated to the Institute of Medicine during its deliberations. A blanket denunciation of all experiments on chimpanzees should be the next step. The onus now falls on the National Institutes of Health to adopt the findings of this report and stop squandering taxpayers’ money on outdated and unethical experiments and on Congress to pass the Great Ape Protection and Cost Savings Act, which would phase out the use of chimpanzees and permanently retire more than 500 federally owned chimpanzees to sanctuaries, where they could live in peace at last.
source:PETA files

Sleep Apnea Treatment May Lower Heart Risks

Study: CPAP Can Lower Many Risk Factors for Heart Disease, Stroke


woman wearing cpap

In addition to improving sleep, an effective treatment for sleep apnea can also improve blood pressure and other risk factors for heart attack, stroke, and type 2 diabetes, new research shows.

Continuous positive airway pressure therapy, or CPAP, helps patients with sleep apnea breathe better during sleep by pushing air into the nose through a mask to keep airways open.

The treatment has been shown to improve daytime sleepiness and reduce blood pressure, but its impact on heart disease, stroke, and diabetes risk factors that are common in patients with sleep apnea has not been well understood.

Results from a study published in the Dec. 15 issue of the New England Journal of Medicine suggest that CPAP is associated with a lower risk for metabolic syndrome, a cluster of symptoms that increase the risk for heart disease, stroke, and diabetes.

Researcher Surendra K. Sharma, MD, PhD, of the All India Institute of Medical Sciences in New Delhi tells WebMD that along with weight loss and lifestyle modification, treatment with CPAP may be an important way to lower heart attack, stroke, and diabetes risk in patients with sleep apnea.

Sleep Apnea, CPAP, and the Heart

More than18 million adults in the U.S. have sleep apnea, according to the National Sleep Foundation, and a significant percentage of them are overweight or obese.

Other than weight loss, CPAP is considered the most effective nonsurgical treatment for patients with moderate to severe sleep apnea.

The new study included 86 patients with sleep apnea, including 75 who had metabolic syndrome.

Study participants were treated with either CPAP or a fake therapy for three months, followed by a month of no treatment and three additional months of the opposite treatment.

Before and after each phase of the study, researchers recorded the participants’ blood pressure, blood sugar, blood fats called triglycerides, hemoglobin A1c levels, neck artery thickness, abdominal fat, and insulin resistance, which measures the body’s ability to use insulin efficiently.

When compared to the fake therapy, three months on CPAP was associated with significantly lower blood pressure, total cholesterol, triglycerides, and LDL cholesterol, the so-called bad cholesterol.

Treatment with CPAP was also associated with a significant decrease in abdominal fat and body mass index (BMI).

It was also associated with a significant decrease in hemoglobin A1c values, which indicate average blood sugar levels over the past two to three months. And 1 in 5 patients with metabolic syndrome before starting CPAP treatment no longer had the condition after three months of treatment.

Lack of Sleep and Chronic Disease

Sleep specialist Meir Kryger, MD, of the Yale University School of Medicine and the VA Connecticut Health System, tells WebMD the findings highlight the growing recognition that sleep disturbances play a significant role in chronic disease.

Kryger is a board member with the National Sleep Foundation.

“It is now clear that patients with heart disease or a metabolic disease like type 2 diabetes should be asked about their sleep habits, and they should be treated if they have sleep apnea,” he says.

Cardiologist Tara Narula, MD, of Lenox Hill Hospital in New York City, says sleep issues have not been a major focus in cardiology in the past. But she says this is changing.

“We are seeing more and more studies linking sleep disorders and stress to [heart disease and stroke risk],” she tells WebMD. “This study suggests that a simple, effective treatment for sleep apnea may help reverse the abnormalities that lead to heart attack and stroke.”

While CPAP may be simple and effective, Kryger acknowledges that most patients don’t like wearing a mask while they sleep.

But he adds that CPAP technology and masks have improved dramatically over the last few years. Most new machines are even able to monitor how often the treatment is used and how well it is working.

source: webMD

Experts share their tips on when to use enterography.

Which patients are best suited for enterography? And if you have a patient who is a good candidate for the procedure, should you use CT or MR? Several enterography experts share their opinions.

On differing implications of active and fibrotic Crohn’s disease

Dr. Michael Gee, PhD

Dr. Michael Gee, PhD, Massachusetts General Hospital

Dr. Michael S. Gee, PhD
Associate Professor, Radiology
Massachusetts General Hospital, Boston

Active inflammatory disease and fibrosis have different indications with respect to treatment. Active inflammation implies on a histologic level that there are neutrophils — a type of white blood cell — and immune cells that are actively invading into the glands and crypts that are in the bowel wall, so that is fundamentally the basis for inflammatory bowel disease. It is almost an autoimmune type of inflammation in which the body’s autoimmune system is attacking the bowel wall.

When we see active inflammation on imaging, this is an indication for medical therapies that are designed to block the body’s immune response against itself. The most recent development has been these biological anti-immunomodulatory response agents for the treatment of inflammatory bowel, such as Remicade (infliximab) or a number of other agents in clinical trials. The premise of all those agents is that they blunt the immune response against the bowel wall. When we see inflammation, the implication is that this immune response is ongoing. It is an indication for the gastroenterologist to initiate or change that immunomodulatory medication regime to optimize immunosuppression.

In contrast, when we see fibrosis of the bowel wall — mural fibrosis — this implies that the immune response has died out. What you are left with is scarring in the bowel wall itself. When there is scarring, that typically causes fixed areas of narrowing that basically are refractory to medical treatment. So if you have a patient who has fibrosis, what typically happens is those areas of scarring cause bowel obstruction because they cause fixed areas of narrowing, and from time to time, patients develop these bowel obstructions because the food they’re eating gets blocked by these strictures. So if a patient is symptomatic and has fibrosis, usually the only way to treat it is to surgically excise the area of stricture. That is the dichotomy between the detection of active inflammation and fibrosis and what it means to clinical outcomes and patient management.

On MR and CT enterography for pediatric patients

Dr. David Bruining

Dr. David Bruining, Mayo Clinic

Dr. David Bruining
Assistant Professor, Gastroenterology
Mayo Clinic, Rochester, MN

Many of our patients are diagnosed between the ages of 16 and 28, and many of them are considered for MR enterography. Particularly, the role of MRE is for patients who are quite young or have serial exams. I don’t think the risk is huge as far as a single CTE exam is concerned, but what we try to do with each patient is to pick out the best exam for them. For patients younger than age 35 who have already had multiple CTs for other reason, I’ll probably order MRE.

However, CT still has a role. In particular, the image acquisition time is much quicker for CT than MR. If I have a very sick patient, I’m worried about how long they will be able to tolerate being on a table. CTE is still my imaging modality of choice. If a patient is unable to follow commands, such as holding their breath, I may still ask for a CT.

This also applies to patients with tremors. For an obese patient or a patient I can’t give glucagon to, I will probably perform CT.

Now with dose reduction techniques, I don’t think the radiation will be as large of a concern. The short answer is that we look at these patients, and pick out the best modality for them and go from there. MR is particularly valuable for young patients who need serial exams.

On enterography for diagnostic small-bowel tumors and occult bleeding

Dr. Khaled Elsayes

Dr. Khaled Elsayes, MD Anderson Cancer Center

Dr. Khaled Elsayes
Associate Professor, Radiology
MD Anderson Cancer Center, Houston

Among the various cancers that appear in the small bowel, enterography has the greatest value for diagnosing preoperative carcinoid tumors. By localizing carcinoid, you will be able to determine the segment of the bowel that should be resected. So preoperative planning is very important and also finding carcinoid.

These patients come to you when the tumor was not found anywhere else in the body. CT enterography is a very good tool to distend the bowel and to visualize and detect these small tumors. If there is any question about small-bowel carcinoma, CT enterography would be the modality of choice.

The other thing we quite often use CT enterography for at MD Anderson is detecting GI bleeding. This tends to be quite helpful for interventional radiologists to chase down the source of the bleeding to embolize it.

On the merits of enteroclysis for small-bowel imaging

Dr. Dean Maglinte

Dr. Dean Maglinte, Indiana University School of Medicine

Dr. Dean Maglinte
Distinguished Professor, Radiology
Indiana University School of Medicine, Indianapolis

When you image the bowel, you need to distend it to be able to exclude any significant disease. To me, enteroclysis is the most reliable approach to rule out disease or confirm its presence.

It is especially valuable for detecting obstructions, for example. You have a patient with intermittent abdominal pain and nausea. You give them oral contrast, and you might not see the obstruction. But if you distend the bowel, the fixed area from some adhesions is easier to see. An adhesion will be exaggerated.

But if you are going to use enterclyosis, you must make sure you use conscious sedation. Nasal intubation is not comfortable. Patients will hate you for doing that, if you don’t sedate them.

For transmural disease, the sensitivities for CT and MR enterography have been high: in the 80% to 90% range. But specificity is not as good for either CT or MR enterography, compared with CT or MR enteroclysis.

You won’t see the scratches in the mucosa associated with very early changes associated with Crohn’s disease with CT or MR enterography. But you can see them with a barium modification of enteroclysis, called air double-contrast enteroclysis, that has been very popular in Japan. With that technique, you can see the inner lining of the small intestine. It will allow you see those mucosal scratches.

source: GE imaging

Enterography raises standard for diagnosing inflammatory bowel disease

CT and MR techniques depict pathology beyond the range of endoscopy.

Enterography is the story of progress made possible from better chemistry applied to contrast media development and the recent leaps in engineering that have revolutionized CT.

This unique imaging technology is directed at the small bowel, an overlapping, undulating, 22-ft-long section of the gastrointestinal (GI) tract remotely located between the stomach and large intestine.

Compared with other organs, the small bowel is subject to a relatively low incidence of disease, according to Dr. Dean Maglinte, a distinguished professor of radiology and imaging sciences at Indiana University School of Medicine. But the symptoms of disorders that do affect it are often nonspecific. For these reasons, the primary role of small-bowel imaging is to rule out the presence of fairly uncommon pathology. These are inflammatory bowel disease, gastrointestinal tract bleeding, and small bowel tumors.

About 80% of the demand for small-bowel imaging stems from Crohn’s disease, which affects up to 600,000 Americans. Disease prevalence has increased 31% since 1991, with pediatric patients accounting for 25% to 30% of the affected population (Inflammatory Bowel Diseases, March 2007, Vol. 13:3, pp. 254-261).

Roles for diagnostic imaging

Patient with active ileocolonic Crohn's disease

Click to enlarge.
Patient with active ileocolonic Crohn’s disease.

Small-bowel imaging guides therapeutic management of Crohn’s disease by informing the clinician about the location, extent, and activity of pathology, according to Dr. Sam Stuart, a radiologist with Royal Free Hospital in London. Imaging aids diagnosis, monitors progression, assists treatment, and identifies small-bowel strictures that may need surgical resection.

CT enterography (CTE) has largely replaced small-bowel follow-through as the imaging modality of choice for Crohn’s disease. Its popularity stems from its ability to noninvasively investigate extraintestinal effects of inflammatory small-bowel disease located outside the reach of x-ray barium imaging.

The Mayo Clinic in Rochester, MN, adopted CT enterography for routine clinical use after the publication of a pivotal study by its own Dr. Craig Solem and colleagues in 2008 (Gastrointestinal Endoscopy, August 2008, Vol. 68:2, pp. 255-266).

Solem’s team prospective efficacy study compared the relative abilities of CT enterography, capsule endoscopy, ileocolonoscopy, and small-bowel follow-through to diagnose Crohn’s disease and determine whether it was active or inactive.

Based on experience with 42 patients, the researchers found that ileocolonoscopy is only slightly more accurate than CT enterography (86% versus 85%) for diagnosis. It was far more sensitive than small-bowel follow-through (82% versus 65%) and significantly more specific than either capsule endoscopy or small-bowel follow-through (89% versus 53%).

“Solem’s study showed us that small-bowel follow-through was inferior,” said Dr. David Bruining, an assistant professor of gastroenterology at the Mayo Clinic. “One of the reasons we have been pushing forward with CTE is because it is a better test.”

Members of Mayo Clinic’s small-bowel imaging group also were drawn to CT — and later MR — enterography because of endoscopy’s limitations. Endoscopes are sometimes unable to extend to areas of disease involvement, and endoscopy findings do not necessarily correlate with disease activity.

“It is not enough to see the patient’s symptoms and to tell patients that they are failing therapy. We need objective evidence,” Bruining said. “That is where CT or MR enterography has made a big impact in practice.”

CT enterography utilization increased steadily at the Mayo Clinic after 2006. It reached a plateau in 2009, with the initial adoption of MR enterography (MRE). Most of the growth in the past two years has shifted to MRE, Bruining said.

Keys to CTE’s diagnostic power

Enterography could not have been developed without high-speed multislice CT. Its development moved in lockstep with the progress of CT from four-slice acquisition in the late 1990s to current 320-detector-row scanners that can complete a whole-body scan in three seconds. Such ultrahigh temporal and spatial resolution can be focused on the small bowel to freeze motion for even a pain-ridden child, while rendering diagnostically superb images of the intestinal lumen, mucosa, and extraintestinal region.

The full extent of the benefits from multislice CT were not revealed, however, until radiologists shifted away from positive contrast material that was so bright that it washed out indications of inflammation in the bowel wall, according to Dr. Peter Higgins, PhD, an assistant professor of gastroenterology at the University of Michigan.

Click to enlarge.
Increased mesenteric vascularity.

The problem was solved when researchers inadvertently tried a negative oral contrast medium.

“It became apparent that just filling the small bowel with negative contrast, food, or fluid was actually better than very bright contrast,” Higgins said.

Decades of experience with barium imaging taught radiologists the value of complete bowel dissention for ensuring thorough examination. The use of neutral enteric contrast agents has proved to be especially well-suited for this role. Such agents allow water in the gut to remain there without bowel wall absorption, Higgins said.

Complete small-bowel distention requires lots of oral contrast. The protocol for routine CT enterography at the Mayo Clinic calls for patients to drink 1.35 L of it in the two hours before imaging. The radiologist also administers intravenous iodinated contrast to enhance extraluminal structures.

MR enterography

Because of radiation concerns about CT enterography, European researchers began developing MR enterography in the early 2000s as an alternative for pediatric patients. The first feasibility study was published in 2005.

A single CTE exam exposes the patient to about 4 mSv of radiation, though the effective dose can be much higher. A longitudinal European study found that 15% of Crohn’s disease patients accumulated more than 75 mSv from radiological procedures in 15 years. The risk of high radiation exposure doubled for patients diagnosed with Crohn’s disease before the age of 17 years (Gut, November 2008, Vol. 57:11, pp. 1524-1529).

The CTE protocol served as a natural template for MRE’s development, with variations added to reflect individual preferences to capitalize on MRI’s inherently higher contrast resolution.

The preferred agent for bowel distention during MR enterography varies from institution to institution, according to Dr. Michael Gee, PhD, an assistant professor of radiology at Massachusetts General Hospital (MGH) in Boston. Most radiologists use a neutral enteric agent, but some Europeans prefer polyethylene glycol (PEG).

Gee’s group at MGH mix a neutral enteric agent mixed with an oral suspension of ultrasmall iron oxide particles. When mixed with water in the bowel, the mixture looks dark on T2-weighted MRI. Before MRE, an intravenous gadolinium-based contrast medium is injected to enhance extraluminal tissue.

Pivotal MRE trial

MR enterography detection of active inflammation and fibrosis

Click to enlarge.
MR enterography detection of active inflammation and fibrosis.

The Mayo Clinic was the site for a key efficacy trial of MR enterography. The prospective study of 23 adult patients by Dr. Hassan Siddiki and colleagues in 2009 concluded that MRE and CTE are about equally sensitive for detecting active small-bowel inflammation, though the CT’s image quality was judged slightly superior (American Journal of Roentgenology, July 2009, Vol. 193:1, pp. 113-121).

Overall, CTE and MRE were both more than 90% sensitive to the presence of positive findings for Crohn’s disease. CTE was somewhat more specific than MRE (88.9% versus 66.7%), but the difference was not statistically significant.

A small prospective trial by Gee and colleagues at MGH published this year found that MRE is at least as good as CTE for determining the initial presence, extent, and severity of Crohn’s disease for pediatric patients (AJR, July 2011, Vol. 197:1, pp. 224-229).

The findings were based on 18 consecutive patients, all of whom were less than 18 years old. They underwent both CTE and MRE to establish an initial primary diagnosis of Crohn’s disease. CTE was used as the reference standard. The sensitivity, specificity, and accuracy of MRE were 90%, 82.6%, and 86.7%, respectively.

Though MRE spares children from radiation exposure, CTE remains the first choice for many radiologists for imaging young patients. They prefer CTE because it is incredibly fast. CTE imaging can be completed in five minutes, compared with 45 minutes for an MRE evaluation. The higher speed greatly reduces the risk of motion artifacts and vomiting from children whose stomachs have been filled with oral contrast.

Diagnostic gold standard

Despite imaging advancements, histology remains the gold standard for Crohn’s disease diagnosis. CTE or MRE help confirm such findings, while establishing the disease’s extent and severity. After a negative biopsy in the face of persistent symptoms, enterography is used to identify inflammatory areas of the bowel for tissue sampling.

Because of superb spatial resolution, CTE is a good choice for establishing the presence and extent of active inflammatory disease. Mural stratification characterized at CTE is the most sensitive finding for active inflammatory disease, according to Dr. Khaled Elsayes, an associate professor of radiology at MD Anderson Cancer Center in Houston. Mural stratification can be appreciated by its trilaminar appearance, with enhanced outer serosal and inner mucosal layers and an interposed submucosal layer of lower attenuation.

A prominent vasa recta, often referred to as a “comb sign,” and increased mesenteric fat attenuation are the most specific features of active Crohn’s disease described by CTE.

Though MRE also can establish these findings, its capabilities extend to water-sensitive, T2-weighted imaging that differentiates between active inflammation and fibrosis. Active inflammation on MRI is characterized by bright areas of the bowel wall on T2-weighted imaging, whereas fibrosis is characterized by a hypointense presentation and also a T2-weighted sequence.

Dynamic gadolinium-contrast enhancement also aids the assessment of bowel wall pathology, with active inflammation revealing itself from early mucosal enhancement followed by delayed enhancement of the rest of the bowel wall. Fibrosis is characterized by an absence of enhancement of the mucosa, according to Gee.

“Between the T2-weighted images and the postcontrast images, we basically get two shots to try to detect fibrosis on MRI that we wouldn’t have the opportunity to look at with CT,” Gee said.

The ability to differentiate between active inflammation and fibrosis is crucial for effective patient management. Active inflammation indicates the presence of reversible strictures that can be treated with anti-inflammatory drugs. Fibrotic strictures require surgical intervention to avoid future bowel obstructions, Elsayes said.

Coping with pediatric radiation exposure

Some clinicians believe that fears about CTE-related radiation will diminish as improved dose reduction techniques are introduced. Two recent studies in particular exemplify how CTE radiation can be reduced without losing image quality.

Dr. Avinash Kambadakone at MGH used iterative reconstruction to cut dose from CTE by about one-third compared with a traditional filtered back-projection reconstruction technique (AJR, June 2011, Vol. 196:6, pp. W743-W752). And at the Cleveland Clinic in Ohio, Dr. Brian C. Allen and colleagues drew from the findings of a prospective trial to recommend optimal settings for an automatic exposure control during CTE performed with 16- and 64-slice scanners (AJR, July 2010; Vol. 195:1, pp. 89-100).

Generally, radiologists have decreased exposure in CTE exams by restricting imaging acquisition to either the vascular or arterial phase, depending on the application.

Dealing with MRE’s high costs

The relatively high cost of MRE can be a problem for clinicians who order it for their young patients. The University of Michigan Medical Center charges $7,000 for an MRE exam compared with $1,500 for CTE, according to Higgins. The higher charge has a few insurers insisting on bizarre ways to reduce their costs, he noted. One payor approved payment for the pelvic portion of an MRE exam, but denied it for the abdominal portion.

At MGH, Gee has seen no evidence of payor resistance to MRE, though his department seeks reimbursement for MRE to only cover specific indications for pediatric patients or evaluations of small-bowel fistulas or abscesses.

In response to an email inquiry, an Aetna spokesperson wrote that it has no clinical policy preventing the use of MRE in younger patients with Crohn’s disease. But he admitted that prior authorization policies applied by individual Aetna plans could be an impediment.

In response to email inquiries, Cigna replied that it covers MRE for children and adults when deemed medically necessary, recognizing the need for MRE for young patients to avoid radiation exposure.

Cigna’s payment experience indicates that MRE is twice as expense as CTE, however. Its average cost for CTE is about $950, compared with about $1,800 for MRE.

In Europe, higher MRE costs have not discouraged clinicians from ordering it, according to Dr. Julian Panes, chief of gastroenterology at the Hospital Clinic of Barcelona in Spain. The costs at Panes’ hospital and the Academic Medical Center in Amsterdam, the Netherlands, are comparable. Both charge from $400 to $467 for MRE and $266 to $300 for CTE.

Other applications

In addition to Crohn’s disease, CTE and MRE are being used to detect small-bowel tumors. Such malignancies are rare, and their symptoms are nonspecific. Clinicians typically test for more likely causes before considering the possibility of small-bowel cancer. At a result, diagnosis is often delayed, thereby increasing the need for a highly sensitive test when it is finally performed, Elsayes said. CTE meets that need with a 90% detection rate for carcinoid and other tumors.

CTE is also showing early promise for tracking down the sources of obscure GI bleeding that evades detection with conventional and capsule endoscopy. These techniques have been typically less than 50% sensitive for localizing the cause of bleeding.

In a recently published trial, Dr. James Huprich, an associate professor of radiology at the Mayo Clinic, and colleagues determined that multiphasic CTE was more than twice as sensitive as capsule endoscopy for finding the source of obscure GI bleeding. The sensitivity of CTE for 16 patients was 88%, compared with 38% for capsule endoscopy (Radiology, September 2011, Vol. 260:3, pp. 744-751).

Future development

MGH radiologists have begun performing 3-tesla MRE, though it has been a challenge, Gee said. Imaging with 3-tesla systems offers an improved signal-to-noise ratio that can be used to either cut exam times or boost image resolution, but the risk of susceptibility artifact is much greater than during 1.5-tesla imaging. Air must be carefully eliminated from the bowel to avoid susceptibility artifacts from affecting the evaluation of the mucosa, he said.

Dr. Seung Soo Lee and colleagues from the University of Ulsan College of Medicine in Seoul, South Korea, reported encouraging results with a triphasic CTE protocol involving 1,800 mL of a neutral enteric agent for bowel distention. The scheme achieved 71% sensitivity this year with CTE in seven patients with positive at capsule endoscopy (Radiology, June 2011, Vol. 259:3, pp. 739-748).

Researchers are also investigating a possible role for diffusion-weighted MR. It may emerge as another way to identify active inflammatory Crohn’s disease by mapping the pattern of edema that restricts water diffusion in the bowel wall, Gee said.

Bruining envisions a promising future for CT enterography. The modality has all the ingredients for broad community-based adoption, he said. Multislice CT is widely available and inexpensive compared with MRI. Low-dose techniques will likely calm fears about radiation exposure, while improved CTE applications, especially the ability to distinguish inflammatory processes from fibrotic disease, will win over gastrointestinal radiologists and gastroenterologist to the merits of the technology.

“These are the kinds of things that are being looked at to see if we can predict the inflammatory component for people with strictures and how well they are likely to respond to therapy,” Bruining said.

source:GE imaging newsletter



Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride.

In spite of more than 100 years of investigations the question of reduced sodium intake as a health prophylaxis initiative is still unsolved.
OBJECTIVES: To estimate the effects of low sodium versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides.
SEARCH STRATEGY: PUBMED, EMBASE and Cochrane Central and reference lists of relevant articles were searched from 1950 to July 2011.
SELECTION CRITERIA: Studies randomizing persons to low sodium and high sodium diets were included if they evaluated at least one of the above outcome parameters.
DATA COLLECTION AND ANALYSIS: Two authors independently collected data, which were analysed with Review Manager 5.1.
MAIN RESULTS: A total of 167 studies were included in this 2011 update.The effect of sodium reduction in normotensive Caucasians was SBP -1.27 mmHg (95% CI: -1.88, -0.66; p=0.0001), DBP -0.05 mmHg (95% CI: -0.51, 0.42; p=0.85). The effect of sodium reduction in normotensive Blacks was SBP -4.02 mmHg (95% CI:-7.37, -0.68; p=0.002), DBP -2.01 mmHg (95% CI:-4.37, 0.35; p=0.09). The effect of sodium reduction in normotensive Asians was SBP -1.27 mmHg (95% CI: -3.07, 0.54; p=0.17), DBP -1.68 mmHg (95% CI:-3.29, -0.06; p=0.04). The effect of sodium reduction in hypertensive Caucasians was SBP -5.48 mmHg (95% CI: -6.53, -4.43; p<0.00001), DBP -2.75 mmHg (95% CI: -3.34, -2.17; p<0.00001). The effect of sodium reduction in hypertensive Blacks was SBP -6.44 mmHg (95% CI:-8.85, -4.03; p=0.00001), DBP -2.40 mmHg (95% CI:-4.68, -0.12; p=0.04). The effect of sodium reduction in hypertensive Asians was SBP -10.21 mmHg (95% CI:-16.98, -3.44; p=0.003), DBP -2.60 mmHg (95% CI: -4.03, -1.16; p=0.0004).In plasma or serum there was a significant increase in renin (p<0.00001), aldosterone (p<0.00001), noradrenaline (p<0.00001), adrenaline (p<0.0002), cholesterol (p<0.001) and triglyceride (p<0.0008) with low sodium intake as compared with high sodium intake. In general the results were similar in studies with a duration of at least 2 weeks.
AUTHORS’ CONCLUSIONS: Sodium reduction resulted in a 1% decrease in blood pressure in normotensives, a 3.5% decrease in hypertensives, a significant increase in plasma renin, plasma aldosterone, plasma adrenaline and plasma noradrenaline, a 2.5% increase in cholesterol, and a 7% increase in triglyceride. In general, these effects were stable in studies lasting for 2 weeks or more.

source:Cochrane database

Reduced uterine contractility may explain increased emergency cesarean section rates in diabetes

The increased rate of emergency caesarean section in pregnant women with diabetes may be explained by poor uterine contractility, according to researchers from the University of Liverpool.

Their data demonstrated that compared with nondiabetic women, those with diabetes had reduced intracellular calcium signals and expression of calcium entry channels. In addition, these women had a reduction in muscle content, as determined by histological examination.

Researchers compared spontaneous, high potassium depolarization and oxytocin-induced contractions in women with diabetes (n=40) and matched controls (n=68) having elective caesarean section. Intracellular calcium was measured to determine the mechanism of differences. In addition, western blotting was performed and the tissues were histologically compared.

Compared with controls, diabetic women had significantly decreased contraction amplitude (2.4 mN vs. 1.5 mN; P<.05) and duration in uteri (1.7 min vs. 0.9 min; P<.05). This was true after controlling for cofounders such as BMI.

According to researchers, reduced contractility was persistent after comparing insulin-treated patients with diet-controlled patients with gestational diabetes.

“Contractility was poorer in the diabetic samples whether arising spontaneously, with oxytocin or high [potassium]; calcium channel expression and signaling were reduced and are likely to account for the reduction in contractility,” they wrote.

In patients with diabetes, myometrium was responsive to oxytocin but did not reach levels found in patients without diabetes.

“The underlying mechanism is related to reduced [calcium] channel expression in intracellular calcium signals and a decrease in muscle mass. We conclude that these factors significantly contribute to the increased emergency caesarean section rate in diabetic patients,” the researchers said.

Source:Endocrine Today

Rotating night-shift work associated with type 2 diabetes risk in women.

Female rotating night-shift workers may be at an increased risk for type 2 diabetes and, therefore, greater weight gain, according to data from a Harvard study.

Researchers assessed data for two cohorts of women: those in the Nurses’ Health Study (NHS) I aged 42 to 67 years (n=69,269) and those in the NHS II aged 25 to 42 years (n=107,915). Follow-up lasted from 18 to 20 years. In the first cohort, 6,165 women developed type 2 diabetes; in the second, 3,961 developed the disease.

Rotating night shifts were defined as at least 3 nights per month, plus days and evenings in that month. Women were asked about the length of time they worked these shifts, and in NHS II, the information was updated every 2 to 4 years.

Night-shift work was associated with an increased risk for type 2 diabetes in both cohorts (P<.001). The HRs were compared for those who did not report rotating night-shift work vs. those who worked various time periods (see Table).

Rotating night-shift work



1-2 years 0.99 (95% CI, 0.93-1.06) 1.13 (95% CI, 1.04-1.23)
3-9 years 1.17 (95% CI, 1.10-1.25) 1.34 (95% CI, 1.23-1.45)
10-19 years 1.42 (95% CI, 1.29-1.55) 1.76 (95% CI, 1.57-1.96)
>20 years 1.64 (95% CI, 1.46-1.83) 2.50 (95% CI, 2.00-3.14)

Adjusting for updated BMI attenuated the association, although it was still significant: pooled HRs were 1.03 (95% CI, 0.98-1.08) for 1 to 2 years of work; 1.06 (95% CI, 1.01-1.11) for 3 to 9 years of work; 1.10 (95% CI, 1.02-1.18) for 10 to 19 years of work; and 1.24 (95% CI, 1.13-1.37) for more than 20 years of work.

“Additional studies are needed to confirm our findings in men and other ethnic groups and to further investigate the underlying mechanisms for the association,” the researchers wrote. “Because a large proportion of the working population is involved in some kind of permanent night and rotating shift work, our study has potential public health significance. Recognizing that rotating night-shift workers are at a higher risk of type 2 diabetes should prompt additional research into preventive strategies in this group.”

Source:Endocrine Today/PLOS