Intrahepatic, extramedullary hematopoiesis mimicking hemangioma on technetium-99m red blood cell SPECT examination.

Cavernous hemangiomas are the most common lesion of the liver. Because of the risk of hemorrhage inherent in percutaneous biopsy of such lesions, noninterventional modalities (such as CT, ultrasound, MRI and Technetium-99m red blood cell imaging) have been utilized for differentiating them from other lesions. The sensitivities and specificities of these techniques vary greatly. Technetium-99m red blood cell imaging with planar and SPECT imaging has been shown to have an overall sensitivity of 89%, a specificity of 100%, and an overall accuracy of 92%. Despite its high accuracy, rare false positives have been reported with Technetium-99m red blood cell imaging with SPECT. Review of the literature indicates four cases of hepatocellular carcinoma, one case of hepatic angiosarcoma, and one case of hepatic metastases from colorectal carcinoma as having an appearance identical to hemangioma with this modality. We present an additional false positive of a focal region of intrahepatic extramedullary hematopoiesis in a patient with Gaucher's disease as having an appearance on Technetium-99m red blood cell imaging with SPECT identical to that of hemangioma.

Pneumatosis intestinalis. Appearance on MR examination.

We describe the magnetic resonance (MR) appearance of pneumatosis intestinalis in two patients. Pneumatosis is suggested by the finding of circumferential collections of air adherent or within the bowel wall. This air is more apparent on gradient-echo images due to "blooming" associated with magnetic field inhomogeneities at air-tissue interfaces. While MR is not routinely indicated as a diagnostic tool for the detection of pneumatosis, the radiologist should nevertheless be familiar with its appearance on MR examination.

Imaging of the spleen: CT with supplemental MR examination.

Splenic lesions tend to be small or infiltrating and vary in size and configuration, making detection difficult, particularly without use of an organ-specific contrast agent. The authors present a series of selected cases to show the value of computed tomography (CT) and magnetic resonance (MR) imaging in depiction of splenic disease. Six major categories are presented: (a) inflammatory disease, (b) splenic cysts, (c) infarction, (d) nonneoplastic and noninfectious diffuse splenic disease, (e) benign tumors, and (f) malignant tumors. CT attenuation of splenic tissue is homogeneous, typically measuring 40-60 HU on non-contrast material-enhanced scans. Splenic attenuation is normally 5-10 HU less than that of liver, a standard of reference used in evaluation of either hepatic or splenic disease. On T1-weighted MR images, the normal signal intensity of the spleen is less than that of hepatic tissue and slightly greater than that of muscle. On T2-weighted images, the spleen shows higher signal intensity, appearing brighter than the liver. CT is currently the choice for evaluation of the spleen; however, MR imaging may be increasingly used as newer pulse sequences and organ-specific contrast agents are developed.

Metastatic adenocarcinoma of the prostate: presentation as a pleural-based mass.

We have presented an unusual case of metastatic prostate carcinoma simulating a primary bone tumor. Although previous reports have described periosteal and "pseudosarcomatous" prostate metastases, no report makes reference to rib involvement. Furthermore, the large soft tissue component is highly unusual. This case illustrates that although such lesions are rare, in the older patient, metastases should be included along with primary tumors in the differential diagnosis of a spiculated bone lesion with prominent soft tissue involvement.

Development of a computer-assisted instructional tool for evaluation and treatment of renal masses. An experiment in hypermedia.

RATIONALE AND OBJECTIVES: Using a personal computer and a commercially available "authoring" application, the authors constructed an interactive hypermedia teaching tool for the evaluation and management of renal masses. METHODS AND RESULTS: Through a series of questions, images, illustrations, hypertext, and graphical flow charts, the user reviews the spectrum of renal masses, including neoplasms, inflammatory disease, cysts, and "pseudomasses." The various imaging modalities (computed tomography [CT], ultrasound [US], magnetic resonance imaging [MRI], and angiography) are illustrated, with selective advantages and disadvantages to each technique highlighted. Selected algorithms for evaluation and treatment of masses are provided. Text, questions, a teaching file, and algorithms form the major sections of the program. Numerous links within and between the major sections of the program, a capacity unique to hypermedia, allow for nonlinear entry into the program, tailored to the individual user. CONCLUSIONS: Preliminarily, medical students and residents have responded positively to this hypermedia project. Furthermore, their comments and criticism have provided important feedback for future updates and enhancements.

CT evaluation of achalasia.

A retrospective review of CT scans on patients referred with either a definitive or a tentative diagnosis of achalasia was undertaken. Twelve patients were identified, of whom nine had proven achalasia. The remaining three patients were later definitively diagnosed with pseudoachalasia, benign stricture, and leiomyomatosis, respectively. Findings in all nine achalasia patients were similar: moderate to marked esophageal dilatation (mean diameter 4.35 cm at carinal level) with normal wall thickness. Findings are in distinct contrast to the three patients with other diseases, in which the degree of esophageal dilatation and/or wall thickness was atypical. Complications in the patients with proven achalasia included secondary carcinoma (one), iatrogenic esophageal perforation (one), and pulmonary aspiration (three). Computed tomography may not be indicated as a routine study, but in complicated cases CT may be invaluable in confirming the diagnosis or in detecting atypical features that may indicate the presence of other diseases or superimposed benign or malignant processes.

Diffuse esophageal leiomyomatosis in a patient with Alport syndrome: CT demonstration.

In a patient with progressive dysphagia, postprandial vomiting, and a history of Alport syndrome, barium and manometric studies had been interpreted as consistent with achalasia, but a subsequent computed tomographic (CT) scan of the thorax was suggestive of a lower esophageal intramural mass. Multiple leiomyomas of the esophagus were later proved at thoracotomy. Differences between adult and pediatric leiomyomas and the association of leiomyomas with Alport syndrome are discussed.