Marc S. Levine

Radiologic diagnosis of gastrointestinal perforation

Perforations of the gastrointestinal tract have many causes. Holes in the wall of gastrointestinal organs can be created by blunt or penetrating trauma, iatrogenic injury, inflammatory conditions that penetrate the serosa or adventitia, extrinsic neoplasms that invade the gastrointestinal tract, or primary neoplasms that penetrate outside the wall of gastrointestinal organs. This article provides a radiologic approach for investigating the wide variety of gastrointestinal perforations. General principles about contrast agents and studies are reviewed, and then perforations in specific gastrointestinal organs are discussed.

Cyclosporine monitoring in patients with renal transplants: two- or three-point methods that estimate area under the curve are superior to trough levels in predicting drug exposure.

The recent introduction of a cyclosporine microemulsion demonstrating less pharmacokinetic variability than the conventional formulation offers the potential for accurately and precisely predicting area under the curve (AUC) with a limited-sampling monitoring strategy. This was studied based on the pharmacokinetic profiles from 55 stable patients with renal transplants who were observed on two occasions at steady state on both formulations. Multiple linear regression analyses were performed on a training dataset from 27 patients, in which combinations of cyclosporine concentrations drawn from 0 to 4 hours postdose were regressed against the full AUC over the dosing interval. Predictor regression equations used concentration combinations ranging from one-point (concentrations at 0, 1, 2, 3, or 4 hours) through five-points (all five concentrations 0 to 4 hours). The predictive performance of these equations was then assessed in the training group with data from a subsequent profiling occasion and in the remaining 28 patients who constituted an independent test group. Prediction bias (mean prediction error) and prediction precision (absolute prediction error) were quantified and compared between formulations. Correlations between predicted and actual AUC were consistently stronger for the microemulsion, suggesting the possibility of more accurate and precise predictions of exposure than from the conventional formulation. For both formulations, the one-point predictors rendered the lowest prediction precision, and predictive performance improved considerably when multiple-point predictors were used. Significantly higher precision and lower variability were observed with the microemulsion for most predictors in the both training and test groups. For the microemulsion, two-point (C0 + C1 or C0 + C2) and three-point (C0 + C1 + C2) predictors yielded relatively unbiased and precise exposure predictions, inasmuch as mean absolute prediction error was less than 10% and 5%, respectively. Hence, a two- or three-point method may provide a clinically important improvement over the use of trough levels in monitoring cyclosporine therapy in patients with renal transplants.

Radiographic imaging of inflammatory bowel disease

Radiographic imaging studies have an important role in the workup of patients with suspected IBD and in the differentiation of ulcerative colitis and Crohns disease. Because of its ability to depict fine mucosal detail, the double-contrast barium study is a valuable technique for diagnosing ulcerative colitis and Crohns disease even in patients with early disease. In contrast, cross-sectional imaging studies such as CT, MR, and ultrasound are useful for showing the effects of these conditions on the wall of the bowel and also for demonstrating intra-abdominal abscesses and other extraluminal findings in patients with more advanced disease. Thus, barium studies and cross-sectional imaging studies have complementary roles in the evaluation of these patients.

Imaging of Bariatric Surgery: Normal Anatomy and Postoperative Complications

Obesity is a disease that has reached epidemic proportions in the United States and around the world. During the past 2 decades, bariatric surgery has become an increasingly popular form of treatment for morbid obesity. The most common bariatric procedures performed include laparoscopic Roux-en-Y gastric bypass, laparoscopic adjustable gastric banding, and laparoscopic sleeve gastrectomy. Fluoroscopic upper gastrointestinal examinations and abdominal computed tomography (CT) are the major imaging tests used to evaluate patients after these various forms of bariatric surgery. The purpose of this article is to present the surgical anatomy and normal imaging findings and postoperative complications for these bariatric procedures at fluoroscopic examinations and CT. Complications after Roux-en-Y gastric bypass include anastomotic leaks and strictures, marginal ulcers, jejunal ischemia, small bowel obstruction, internal hernias, intussusception, and recurrent weight gain. Complications after laparoscopic adjustable gastric banding include stomal stenosis, malpositioned bands, pouch dilation, band slippage, perforation, gastric volvulus, intraluminal band erosion, and port- and band-related problems. Finally, complications after sleeve gastrectomy include postoperative leaks and strictures, gastric dilation, and gastroesophageal reflux. The imaging features of these various complications of bariatric surgery are discussed and illustrated.

A Systematic Review of the Effect of cyp3a5 Genotype on the Apparent Oral Clearance of Tacrolimus in Renal Transplant Recipients

Tacrolimus is a commonly used immunosuppressive agent in renal transplantation. Therapeutic drug monitoring of tacrolimus is recommended because it demonstrates wide pharmacokinetic interpatient variability. Part of that variability may be the result of metabolism by cytochrome P450 3A5 (CYP3A5), which is only expressed in some adult individuals. The expression of CYP3A5 has been linked to the CYP3A5 genotype, in which individuals with one or more wild-type allele (CYP3A5*1) are considered CYP3A5 expressors, and individuals homozygous for the mutant allele CYP3A5*3 are considered nonexpressors. An association has been established between CYP3A5 genotype (expressors versus nonexpressors) and tacrolimus dose requirements to achieve target concentrations. Tacrolimus pharmacokinetic variability is based on bioavailability and systemic clearance, which are represented by apparent oral clearance. The focus of this review was to use a systematic method to investigate whether the CYP3A5 genotype has an effect on the apparent oral clearance of tacrolimus in renal transplant recipients. A total of five studies were identified that reported apparent oral clearance in CYP3A5 expressors and CYP3A5 nonexpressors. The weighted mean apparent oral clearance was found to be 48% lower in CYP3A5 nonexpressors than CYP3A5 expressors (range, 26%-65%). This difference in apparent oral clearance could be used in future studies to guide initial dosing strategies of tacrolimus in renal transplant recipients based on genotype.

Donor-derived Strongyloides stercoralis infections in renal transplant recipients

Background. Donor-derived Strongyloides stercoralis infection occurs rarely after transplantation, and the risk factors are not well understood. We present cases of two renal allograft recipients who developed Strongyloides hyperinfection syndrome after receipt of organs from a common deceased donor who received high-dose steroids as part of a preconditioning regimen. Methods. The two renal transplant patients who developed Strongyloides hyperinfection syndrome are reported in case study format with review of the literature. Results. Microscopic examination of stool from one renal transplant patient and of tracheal and gastric aspirates from the other transplant patient revealed evidence of S. stercoralis larvae. Retrospective testing of serum from the deceased donor for Strongyloides antibodies by enzyme-linked immunosorbent assay was positive at 11.7 U/mL (Centers for Disease Control reference >1.7 U/mL positive). One patient was treated successfully with oral ivermectin. The other patient also had complete resolution of strongyloidiasis, but required a course of parenteral ivermectin because of malabsorption from severe gastrointestinal strongyloidiasis. Conclusions. These case studies provide some of the best evidence of transmission of S. stercoralis by renal transplantation. Because of the high risk of hyperinfection syndrome and its associated morbidity and mortality, high-risk donors and recipients should be screened for Strongyloides infection, so that appropriate treatment can be initiated before the development of disease. This study indicates that parenteral ivermectin can be used safely and effectively in patients in whom severe malabsorption would preclude the effective use of oral formulation. These cases also suggest that reconsideration should be given for the safety of steroids in donor-preconditioning regimens.

Epiphrenic Diverticulum: Clinical and Radiographic Findings in 27 Patients

The purpose of our study was to reassess the clinical and radiographic findings in patients with epiphrenic diverticula. A search of our radiology files revealed 27 patients with epiphrenic diverticula within 10 cm of the gastroesophageal junction. Medical records and radiographic reports and images were reviewed to determine the clinical and radiographic findings. Twenty-three patients had a solitary epiphrenic diverticulum, three had two diverticula, and one had three diverticula. The diverticula arose from the right side of the distal esophagus in 19 patients and the left side in eight. The diverticula had a mean width of 4.4 cm and a mean height of 3.7 cm. Other findings included prolonged retention of barium in the diverticula in 19 patients, preferential filling in 11, retained debris in 5, regurgitation of barium or debris in 5, compression of the esophagus in 5, pseudodiverticula formation in 3, and ulceration in 1. We found a significant correlation between the width of the diverticulum and preferential filling with barium. Twelve patients had abnormal esophageal motility, with diffuse esophageal spasm in two. Seventeen patients had symptoms attributable to the diverticulum (dysphagia in 11 and/or reflux symptoms in 12). We also found a significant correlation between the size or preferential filling of the diverticulum and the presence of symptoms. Conversely, we found no correlation between esophageal dysmotility and the presence of symptoms. Our experience suggests that the development of symptoms in patients with epiphrenic diverticula is more likely to be related to the morphologic features of the diverticula than to underlying esophageal motility disorders.

Achalasia: a disease of varied and subtle symptoms that do not correlate with radiographic findings

Achalasia: a disease of varied and subtle symptoms that do not correlate with radiographic findings

Congenital esophageal stenosis in adults

Abstract OBJECTIVE: Congenital esophageal stenosis is thought to be a rare disease confined to infancy and childhood with only a few case reports in adults described. METHODS: We report five patients between the ages of 19 and 46 yr who presented with this disorder over a 2-yr period. RESULTS: Patients had been labeled with reflux strictures, webs, or as idiopathic in the past. All patients had chronic solid food dysphagia, some since early childhood. The location of the stricture varied, occurring in the mid or proximal esophagus in four, but throughout the esophagus in one. Radiographic and endoscopic appearance was a smooth concentric stricture or multiple rings, sometimes tracheal in appearance. Endosonography was performed in two patients, both of whom had focal circumferential hypoechoic wall thickening with disruption of the normal layer pattern corresponding to the areas of luminal narrowing. All patients dilated had good symptomatic response, with resolution of symptoms up to 6 months in follow-up. CONCLUSIONS: We suggest that congenital esophageal stenosis does occur in adults and may be underrecognized. Its endosonographic appearance is described.

Barrett's esophagus in scleroderma: Increased prevalence and radiographic findings

Ten of 27 patients (37%) with scleroderma who underwent endoscopy at our hospital between 1980 and 1984 for symptoms of reflux esophagitis had biopsy-proven Barretts esophagus. Two of those 10 patients had esophageal adenocarcinomas. In a blinded review of esophagrams (all but 2 using double-contrast technique) from 16 of the 27 patients, only 1 patient was thought to be at high risk for Barretts esophagus due to a high esophageal stricture with an adjacent reticular pattern of the mucosa. The latter patient had biopsy-proven Barretts mucosa. Eight patients were thought to be at moderate risk for Barretts esophagus due to reflux esophagitis and/or distal strictures in 6 and polypoid intraluminal masses in 2. Three of the 6 patients with esophagitis and/or strictures had Barretts esophagus, and both patients with masses had adenocarcinomas arising in Barretts mucosa. Finally, 7 patients who had no esophagitis or strictures were thought to be at low risk for Barretts esophagus. None of those 7 had histologic evidence of Barretts mucosa. Thus, the major value of double-contrast esophagography is its ability to classify patients into high-, moderate-, and low-risk for Barretts esophagus to determine the relative need for endoscopy and biopsy in these patients.