Shuvro Roy-Choudhury

Relative Threshold of Detection of Active Arterial Bleeding: In Vitro Comparison of MDCT and Digital Subtraction Angiography

OBJECTIVE The objective of our study was to determine the relative sensitivity and the lowest threshold of bleeding detectable with digital subtraction angiography (DSA) and with MDCT using an in vitro physiologic system. MATERIALS AND METHODS A closed pulsatile cardiopulmonary bypass circuit was connected to tubes traversing a water bath to simulate the abdominal aorta and inferior vena cava. Three smaller interconnecting acrylic plastic tubes were connected as branches to the aortic tubing to simulate branch vessels. One of the three tubes, the control, had no holes in it, one had a 100-microm hole, and one had a 280-microm hole. The leakage rates were predetermined with a cardiac output of 2 and 4 L/min and with a mean arterial pressure (MAP) ranging from 30 to 100 mm Hg for each hole size. The following studies were performed for each of the predetermined leakage rates. For study 1, 16-MDCT was performed using bolus tracking after 35 mL of contrast medium had been injected into a simulated peripheral vein. For study 2, DSA was performed using a 4-French straight catheter placed 10 cm proximal to the holes (selective first aortic branch cannulation). For study 3, DSA was performed with a catheter placed in the small branch at the site of the hole (highly superselective). For study 4, 16-MDCT was performed with a catheter placed as in study 2, 10 cm proximal to the holes, for the detection of lower leakage rates. Cine loops of MDCT and DSA images were examined by two blinded observers to detect extravasation from the holes in the tubes (i.e., the branch arteries). Interobserver agreement was studied using Cohens kappa statistic. RESULTS The threshold to detect bleeding was as follows for each study: For IV contrast-enhanced MDCT (study 1), it was 0.35 mL/min; DSA with a catheter 10 cm proximal to the holes (study 2), 0.96 mL/min; DSA with a catheter at the holes (study 3), 0.05 mL/min [corrected] or lower; and intraarterial selective MDCT (study 4), 0.05 mL/min [corrected] or lower. The ease of detection improved with increasing MAPs and larger volumes of leakage. Interobserver correlation was excellent. CONCLUSION In vitro, i.v. contrast-enhanced MDCT is more sensitive than first-order aortic branch-selective DSA in detecting active hemorrhage unless the catheter position is highly superselective and is close to the bleeding artery. These results suggest that MDCT can be used as the initial imaging technique in the diagnosis of active hemorrhage if the clinical condition of the patient allows.

Direct Erosion and Prolapse of Esophageal Stents into the Tracheobronchial Tree Leading to Life-threatening Airway Compromise

Covered or uncovered self-expanding metal stents are currently used for the palliative treatment of neoplastic esophageal obstructions or compressions and malignant esophageal leaks or fistulas. This small series, from three different European hospitals, highlights the unusual but significant complication of esophageal stent perforation followed by erosion and prolapse of the endoprosthesis into the tracheobronchial tree causing acute airway compromise or aspiration. Possible causal mechanisms and means of treatment are discussed to raise physician awareness of this life-threatening complication.

More than meets the eye: subtle but important CT findings in Bouveret's syndrome.

OBJECTIVE Gallstones are a rare cause of duodenal or gastric outlet obstruction and therefore are not commonly suspected. Riglers radiographic triad of pneumobilia, bowel obstruction, and an ectopic gallstone is seen in few of these patients. The symptoms are insidious and nonspecific, and the diagnosis is usually made radiologically. Although CT scans are far more sensitive, 25% of cases are still missed, often because the size of the offending gallstone is underestimated. CONCLUSION Better assessment of stone size, and therefore higher accuracy of diagnosis, could be achieved if attention is paid to more subtle but nonetheless important signs. These include compressed air in dependent areas of the duodenal lumen, an area of soft-tissue rather than fluid density surrounding the calcified rim of the stone, and a faint radiolucency in or beyond this soft-tissue area that could represent laminations of fat or air in the stone.

Extracolonic findings (ECF) on CT colonography (CTC) in patients presenting with colorectal symptoms

Background Computed tomographic colonography (CTC) is now an established method for imaging the colon and rectum in the screening and symptomatic setting. Additional benefit of CTC is the ability to assess for extracolonic findings especially in patients presenting with colorectal symptoms. Purpose To determine prevalence of extracolonic findings (ECF) in symptomatic patients undergoing CTC and determine accuracy of CTC for exclusion of significant abdominal disease and extracolonic malignancy (ECM). Material and Methods A total of 1359 unenhanced prone and postcontrast supine CTC studies were performed between March 2002 and December 2007. ECF were retrospectively classified according to C-RADS criteria into E1 to E4 findings. For ECM, a gold standard of clinical and/or radiological follow-up supplemented with data from the regional cancer registry with a median follow-up of 42 months was created. Sensitivity and negative predictive values for ECM was calculated. Results Following exclusions, 1177 CTCs were analyzed. Of 1423 extracolonic findings reported, 328/1423 (23%) E3 and 100/1423 (7%) E4 (including six eventual FP studies) findings were identified. Thirty-two ECMs were confirmed following further investigations. Seven further small ECMs were detected during the entire follow-up, of which two were potentially visible in retrospect (false-negative studies). Additional tests were generated from 55/1177 (4.7%) studies. Sensitivity and negative predictive value for ECM was 94.1% (95% CI 78.9–98.9%) and 99.8% (95% CI 99.3–99.9%), respectively. Conclusion One in 37 patients were found to have an ECM. Two potentially detectable cancers were missed. Only a small proportion of patients underwent additional work-up.

CT Colonography after Colorectal Cancer Resection: A One-Stop Assessment of Metachronous Mucosal Lesions, Local Recurrence, and Distant Metastases

Summary of ADC Measurements for Fetuses with and without Placental Insuffi ciency ParameterRegion 1 * Region 2 † Fetuses with Placental Insuffi ciency ( n = 33)Fetuses without Placental Insuffi ciency ( n = 69)Fetuses with Placental Insuffi ciency ( n = 33)Fetuses without Placental Insuffi ciency ( n = 69) Mean 1.454 1.771 1.415 1.752 Median 1.461 1.773 1.397 1.767 Standard deviation 0.106 0.208 0.132 0.181 Confidence interval 1.428, 1.498 1.705, 1.805 1.358, 1.455 1.686, 1.818 Note.— All measurements are given in 10 2 9 m 2 /sec. The average measurements of both readers are given. * Region 1 is located 2 cm from the insertion of the umbilical cord. † Region 2 is loca ted 5 cm from the insertion of the umbilical cord. “Reduction in False-Positive Results after Introduction of Digital Mammography: Analysis from Four Population-based Breast Cancer Screening Programs in Spain.” Radiology 2011;258(2):388–395 Page 388, the affi liations at the bot-tom left should read as follows: From the

Trends in whole colonic imaging

In our experience, the change in imaging modality is purely due to a change in hospital physician requesting, as general practitioners ’ referral patterns have not changed over the past 7 years. In our unit in 2009, general practitioners accounted for only 4.6% (26/561) of CTC referrals, but 39% (126/326) of DCBE referrals ( P 0.0001). Although the survey did not specifi cally address this, we would expect that a similar pattern would be observed in Sweden. It will take time for community practitioners to learn of the availability and advantages of CTC, and hospital doctors should do more to educate their colleagues in primary care. Although DCBE continues to be performed routinely, its end appears to be in sight.

Drainage of Abdominal Fluid Collections

Percutaneous abscess drainage (PAD) is now standard therapy for patients with intraabdominal abscess who do not have other indications for surgery. The vast majority of collections or abscesses can be managed with an appropriately sized and positioned catheter. This section will deal with some general principles of abscess drainage as well as look into some specific locations like perihepatic (subphrenic and subhepatic), gall bladder bed, splenic bed, lesser sac, paracolic, and retroperitoneal abscesses.