Image guided localized 31P magnetic resonance spectroscopy of acute urinary tract obstruction

Imaging for ureteropelvic junction obstruction in adults

The three goals of imaging for ureteropelvic junction (UPJ) obstruction are to determine the presence and degree of renal obstruction, to assess renal function, and to determine the cause of the problem. The diagnostic techniques are intravenous urography, which is unreliable; ultrasonography, with the addition of pulsed Doppler technology; diuretic scintigraphy; and pressure-flow studies (Whitaker test), which is the only direct clinical test of renal outflow resistance. Voiding cystography, retrograde ureteropyelography, and CT have utility in some patients. In determining the cause of obstruction, the patient often is evaluated for crossing vessels using angiography, endoluminal ultrasonography, or spiral CT. It is not possible to formulate a single algorithm for radiographic evaluation of suspected UPJ obstruction, but in the average adult patient, urography and diuretic scintigraphy are sufficient.

Endorectal surface coil MR imaging of prostatic carcinoma with the inversion-recovery sequence

The value of inversion-recovery (IR) sequences in the diagnosis and staging of prostatic carcinoma with magnetic resonance (MR) imaging was studied. Twenty-six patients with carcinoma of the prostate were imaged at 1.5 T with an endorectal surface coil and with a variety of IR sequences and a set of spin-echo (SE) sequences for comparison. Ex vivo prostate specimens were imaged again at the same field strength. The two images were correlated with histologic sections. Cancer was identified with MR imaging in 96% of patients. Of the tumors more than 4 mm in diameter, 87% were identified on T2-weighted SE images, whereas only 26% were identified on IR images. However, IR images may be more useful in local staging of carcinoma. Gross capsular infiltration was present in only two patients; however, it was detectable (and excluded in five other patients) by means of IR images. It was not detectable on SE images. The high quality of images obtained with the endorectal coil was confirmed. The authors conclude that addition of the IR sequence to MR imaging with the endorectal coil may improve the usefulness of this examination.