Type 1 signal intensity changes on MR images have a high positive predictive value in the identification of a pain generator.

Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.

Although a chemical shift imaging technique and a T2*-weighted sequence helped correctly differentiate among the groups of adrenal masses, the degree of overlap suggests that it is still difficult to evaluate disease in individual patients.

Ultrasonographic (US) examinations of the upper abdomen were performed in 80 patients with Gaucher disease. Of the 49 patients that had not undergone splenectomy, 47 had splenic enlargement. Sixteen patients had multiple lesions in the spleen. Most patients had discrete hypoechoic lesions that corresponded pathologically to focal homogeneous clusters of Gaucher cells. Several patients had similar lesions that were hyperechoic and were composed of Gaucher cells and fibrosis or infarction. A few patients had a geographic pattern of irregular areas of involvement of Gaucher cells among normal splenic parenchyma. The liver was often enlarged but otherwise sonographically unremarkable. Patients with Gaucher disease often have US examinations of the left upper quadrant for abdominal pain. A variety of US findings in the spleen typical for Gaucher disease should be recognized and not interpreted as acute changes.

Magnetic resonance imaging was performed in 30 patients with adrenal masses. The abnormalities included adrenal adenomas (n = 10), carcinomas (n = 2), pheochromocytomas (n = 12), and adrenal metastases (n = 6). By the ratio of the signal intensity of the adrenal mass to that of the liver, adenomas could be distinguished from adrenal metastases, adrenal carcinomas, and pheochromocytomas. Metastases and pheochromocytomas could generally be differentiated.