Faculty Bibliography

Pelvic inflammatory disease (PID) is a common medical problem, affecting nearly 1 million women each year. Although the radiology literature is replete with discussions of the sonographic manifestations of PID, little has been published regarding the computed tomographic (CT) appearances of this entity. CT findings in early PID include obscuration of the normal pelvic floor fascial planes, thickening of the uterosacral ligaments, cervicitis, oophoritis, salpingitis, and accumulation of simple fluid in the endometrial canal, fallopian tubes, and pelvis. As the disease progresses, this simple fluid may become complex and the inflammatory changes may progress to frank tubo-ovarian or pelvic abscesses. Reactive inflammation of adjacent structures is common and can manifest as small or large bowel ileus or obstruction, hydroureter and hydronephrosis, right upper quadrant inflammation (Fitz-Hugh-Curtis syndrome), or peritonitis. Familiarity with the CT appearances of these manifestations is important for timely diagnosis and treatment of PID and its complications

PURPOSE: To determine the effects of cyst diameter and location (intrarenal, exophytic), renal attenuation, section collimation, and computed tomographic (CT) interscanner variability on renal cyst pseudoenhancement in a phantom model. MATERIALS AND METHODS: A customized anthropomorphic phantom was designed to accept 40-, 140-, and 240-HU renal inserts containing intrarenal and exophytic 7-, 10-, and 15-mm cysts. Each phantom and insert were scanned with five different helical CT scanners by using 1.0-1.5-mm, 2.50-3.75-mm, 5.0-mm, 7.0-8.0-mm, and 10.0-mm section collimation. Means and SDs of CT number measurements were obtained for each cyst within each variably 'enhanced' renal insert. Mixed-model analysis of variance accommodating heteroscedasticity of data was used to assess the effect of scanner type, section collimation, and cyst diameter on cyst attenuation. RESULTS: Pseudoenhancement (range, 10.3-28.3 HU), observed by using effective section collimation equal to or less than 50% of cyst diameter, occurred in 34 (38%) of 90 intrarenal cyst measurements. Pseudoenhancement was observed with all five CT scanners, though the magnitude of the effect was nonuniform. Significant interactions were noted between renal cyst diameter, background renal attenuation, and CT scanner type in terms of their effects on cyst attenuation. No appreciable pseudoenhancement was observed with exophytic cysts. CONCLUSION: Pseudoenhancement is maximal when small (< or = 1.5-cm) intrarenal cysts are scanned during maximal levels of renal parenchymal enhancement. The magnitude of this effect varies with scanner type but may be large enough to prevent accurate lesion characterization, despite use of a thin-section helical CT data acquisition technique

Invasive aspergillosis is an opportunistic infection that characteristically affects the immunocompromised host, resulting in a high degree of morbidity and mortality. Although the portal of entry is usually pulmonary, there are rare reports of invasive aspergillosis localized to the gastrointestinal tract. In addition, haematological spread may develop, with life threatening disseminated infection involving the vital organs and the gastrointestinal tract. Although disseminated infection is well recognized, the CT findings of gastrointestinal disease have not been reported to our knowledge. We describe the CT findings in a patient with invasive aspergillosis involving the gastrointestinal tract, which resulted in intestinal ischaemia complicated by small bowel obstruction

PURPOSE: To compare the diagnostic accuracy of focused helical computed tomography (CT) with orally administered contrast material with that of nonfocused helical CT with orally and intravenously administered contrast material. MATERIALS AND METHODS: After receiving oral contrast material, 228 patients with clinically suspected appendicitis underwent focused appendiceal CT (5-mm section thickness, 15-cm coverage in the right lower quadrant). Immediately thereafter, helical CT of the entire abdomen and pelvis was performed following intravenous administration of contrast material (abdomen, 7-mm section thickness; pelvis, 5-mm section thickness). Studies were separated and independently interpreted by three observers who were blinded to patient names. Diagnoses were established by means of surgical and/or clinical follow-up findings. RESULTS: Fifty-one (22.4%) of 228 patients had acute appendicitis. Readers diagnosed appendicitis with 83.3%, 73.8%, and 71.4% sensitivity and 93.0%, 92.3%, and 97.9% specificity with focused nonenhanced appendiceal CT. Readers diagnosed appendicitis with 92.9%, 92.9%, and 88.1% sensitivity and 93.7%, 95.1%, and 96.5% specificity with nonfocused enhanced CT. Summary areas under the receiver operating characteristic curve estimates for focused nonenhanced and nonfocused enhanced CT were 0.916 and 0.964, respectively; the differences were statistically significant (P <.05) for two of three readers. All readers demonstrated higher sensitivities for detecting the inflamed appendix with nonfocused enhanced CT. Appendicitis was missed with focused CT in two patients whose inflamed appendix was not included in the imaging of the right lower quadrant. All readers were significantly more confident in diagnosing alternative conditions with nonfocused enhanced CT. CONCLUSION: Diagnostic accuracy of helical CT for acute appendicitis improved significantly with use of intravenous contrast material

Omental infarction, an uncommon cause of acute abdominal pain, is the result of compromised perfusion to the greater omentum. Although its etiology remains uncertain, predisposing factors include obesity [Surg. Today 30 (2000) 451], strenuous activity [N. Z. Med. J. 111 (1998) 211], trauma, and idiopathic omental torsion. Often confused with acute appendicitis or cholecystitis on clinical grounds [Surg. Today 30 (2000) 451], its diagnosis has traditionally been one of exclusion, based on intraoperative and pathologic findings. This diagnosis can be made radiologically based on the characteristic findings of an inflammatory mass containing fat and fluid. We describe a case of right lower quadrant omental infarction temporally related to bowel surgery

Colonic ischemia isolated to the cecum is a rare entity. The authors evaluated two patients who underwent computed tomography (CT) because appendicitis was suspected at clinical examination. CT findings were suggestive of isolated cecal ischemia or infarction. Surgical-histopathologic findings helped confirm the presumptive CT diagnoses. Isolated cecal infarction should be included in the differential diagnosis of acute right lower quadrant pain

PURPOSE: To determine if simple renal cysts may be accurately characterized with helical computed tomography (CT) during peak levels of renal enhancement. MATERIALS AND METHODS: Water-filled 'cysts' were suspended in varying concentrations of iodine solution, meant to simulate varying levels of renal enhancement, within an abdominal phantom. Volume-averaging effects were minimized by scanning cylindric 5-30-mm cysts with a helical technique (collimation, 5 mm; pitch, 1:1). Axial and helical techniques were then compared, and volume-averaging effects were evaluated by scanning 10- and 20-mm round cysts with 3-, 5-, and 7-mm collimation at background attenuation levels of 100 and 200 HU. RESULTS: Cylindric cyst attenuation increased consistently with increasing background attenuation. As background attenuation increased by 90 HU, attenuation increased by 11-17 HU in small (5- or 10-mm) cysts, and by 7-9 HU in large (15-30-mm) cysts. As background attenuation increased by 180 HU, attenuation increased by 18-28 HU in small cysts and by 10-15 HU in large cysts. Spherical cyst attenuation differences were maximized when smaller cysts were imaged with larger collimation, which is when volume-averaging effects became apparent. Axial and helical CT numbers did not differ substantially. Computer simulation studies showed that the observed effect could not be explained by beam hardening alone. CONCLUSION: Pseudoenhancement of renal cysts may occur if helical CT is performed during peak renal enhancement. CT algorithm modification may be necessary to correct for this effect, which is likely related to an inadequate algorithmic correction for beam hardening