Andres Ayoob

Journal Club: Prevalence of flawed multiple-choice questions in continuing medical education activities of major radiology journals.

OBJECTIVE The purpose of this study was to assess whether the continuing medical education (CME) multiple-choice questions (MCQs) in three major radiology journals adhere to standard question-writing principles. MATERIALS AND METHODS All CME MCQs (total of 181) in the January 2013 editions of the AJR, RadioGraphics, and Radiology composed the test sample. Each question was evaluated by three reviewers for compliance with seven MCQ-writing guidelines that have been documented in the medical education literature as associated with frequent flaws in medical CME. RESULTS Seventy-eight of the 181 (43%) questions contained one to four flaws. CONCLUSION A large fraction of radiology CME questions violate standard question-writing principles.

The bowel wall target sign.

Traditionally, a target configuration describes concentric circles [1]. So when CT depicts abnormally thickened bowel wall as concentric rings of varying attenuation, the imaging appearance has been dubbed the target sign (Fig. 1) [2]. On intravenous contrast enhanced CT without positive enteric contrast material (Fig. 2 a, b), the target sign comprises three rings of alternating attenuation. Two high attenuation value rings—mucosa (inner ring) and muscularis propria (outer ring)—are separated by low attenuation value submucosa (middle ring), presumably reflecting edema or fat [3, 4]. As a differential diagnostic consideration, while the sign is associated with bowel wall thickening of varied etiology (infection, inflammation, ischemia, shock bowel, and radiation), it generally does not occur in neoplasia [5].

Coffee bean sign

The coffee bean sign is a metaphor describing the classic radiographic appearance of a closed loop obstruction, most notably associated with sigmoid volvulus [1, 2]. Twisting of the sigmoid colon about its mesenteric axis creates an inverted, U-shaped, and a gas-filled segment of dilated bowel originating in the pelvis and extending cephalad. A central linear opacity bisects the dilated loop (Fig. 1a), mimicking the cleft of a coffee bean (Fig. 1b). This central line represents the ‘‘double’’ thickness of apposed bowel walls [3] (Fig. 2). Failure to recognize this finding may lead to delayed diagnosis with increased risk of ischemia, infarction, and perforation. Emergent operation for sigmoid volvulus has been associated with 24% mortality, compared with 6% in an elective setting [4].

Imaging of Common Solid Organ and Bowel Torsion in the Emergency Department

OBJECTIVE This article will discuss the most common forms of torsion encountered in the emergency department. CONCLUSION Torsion refers to the twisting of an object about its axis and represents the pathophysiologic mechanism underlying an important group of disorders affecting both the bowel and the solid organs of the abdomen and pelvis. Although these disorders typically present with the acute onset of pain, clinical findings are often nonspecific, with imaging playing a key role in diagnosis. Missed or delayed diagnosis may result in complications, such as ischemia; end-organ loss; and, in some cases, death. Therefore, it is critical to have a thorough understanding of the pathophysiology and imaging findings of these entities to avoid the morbidity and mortality associated with a missed or delayed diagnosis.

Endometriosis revisited: an imaging review of the usual and unusual manifestations with pathological correlation

The manifestations of endometriosis commonly present a diagnostic challenge to the gynecologist and radiologist. Familiarity with its varied presentations may allow for a more accurate diagnosis. The goal of this review is to the present the imaging spectrum of endometriosis, less common sites of involvement as well as the potential rare complications. Relevant surgical and histopathological correlation is also provided. In addition to clinical evaluation and sonography, MRI is a highly accurate imaging modality in the diagnosis of endometriosis. It possesses a distinctive advantage over other modalities in that it allows a complete survey of the pelvic compartments. The potentially devastating effects of endometriosis include pelvic pain and even infertility. Since standard treatment is surgical, the radiologist needs to be familiar with the various manifestations in order to aid diagnosis for appropriate management.

Inverted V sign

Despite the ever-increasing utilization of CT, a supine abdominal radiograph can still be the ‘‘presenting’’ imaging study for patients with acute abdominal pain. Although less sensitive than upright or left lateral decubitus views, a supine frontal abdomen view thus can present the initial opportunity to detect pneumoperitoneum [1]. Among the many described radiographic signs is an ‘‘inverted V’’ visible in the pelvis (Fig. 1). Superomedially directed oblique lines are thought to represent gas outlining peritoneal folds that overlie either the obliterated umbilical arteries [2], or the inferior epigastric arteries [3]. As with any imaging evidence of pneumoperitoneum, the inverted V should prompt a search for perforated viscus.

Bird’s beak sign

The bird’s beak sign metaphorically describes the fluoroscopic appearance of sigmoid volvulus. The sigmoid colon twists around its mesenteric axis, narrowing the lumen with resultant varying degrees of obstruction. On contrast enemas, the narrowed lumen just distal to the point of obstruction shows smooth tapering that resembles a bird’s beak [1] (Fig. 1). Similar findings at CT likewise point to the correct diagnosis [2] (Fig. 2).

Soft-tissue rim sign

A useful clue during CT evaluation of urinary tract calculi, the soft-tissue rim sign represents ureteral wall edema surrounding a calculus at the level of stone impaction. Circumferential soft tissue surrounds the high attenuation value calculus (Fig. 1) [1, 2]. This rim sign can be helpful in distinguishing ureteral calculi from venous calcifications (phleboliths) that typically lack a circumferential soft-tissue margin, but instead have a ‘‘tail’’ of soft-tissue attenuation thought to represent the thrombosed parent vein—one of the several ‘‘comet-tail’’ signs (Fig. 2) [3]. These clues are particularly helpful in patients with a paucity of intra-abdominal fat, in whom the ureter is difficult to identify.

Core curriculum illustration: blunt traumatic mesenteric injury

Initial CT images with intravenous contrast show a left upper quadrant mesenteric hematoma containing a small focus of high attenuation which is similar in attenuation to that of the aorta, raising suspicion for active vascular contrast extravasation (Figs. 1 and 2). Delayed CT imaging (approximately 3 min following initial imaging) through the mesenteric hematoma shows change in appearance of the high-attenuation focus with an increase in size, a decrease in attenuation, and a change in shape between initial and delayed images (Fig. 3). These findings are diagnostic of active vascular contrast extravasation. Laparotomy showed a mesenteric tear with active bleeding. Discussion

Classic Cushing's syndrome in a patient with adrenocortical carcinoma.

Adrenocortical carcinoma is an aggressive but rare neoplasm of the adrenal cortex, with an estimated incidence of approximately 2.5 per one million patients. The prognosis for patients with adrenocortical carcinoma is often very poor. Patients often present with symptoms of hormone hypersecretion but may also present with pain or a palpable mass. Imaging plays an important role in preoperative planning when clinical and biochemical findings are compatible with adrenal cortical carcinoma. We report a case of adrenocortical carcinoma in a young woman who presented with classical Cushing syndrome, but who had an atypical hormonal profile.