Renal cell carcinoma is the most common primary tumor of the kidney, with more than 30,000 new cases diagnosed in the United States each year. With the widespread use of cross-sectional imaging, many tumors are detected incidentally. Single- and multidetector computed tomography (CT) have helped refine the diagnostic work-up of renal masses by allowing image acquisition in various phases of renal enhancement after intravenous administration of a single bolus of contrast material. The scanning protocol should include unenhanced CT followed by imaging during the corticomedullary and nephrographic phases of enhancement. The nephrographic phase is the most sensitive for tumoral detection, while the corticomedullary phase is essential for imaging the renal veins for possible tumoral extension and the parenchymal organs for potential metastases. Knowledge of the tumoral stage at the time of diagnosis is essential for prognosis and surgical planning. The accuracy of CT for staging has been reported to reach 91%, with most staging errors related to the diagnosis of perinephric extension of tumor. Three-dimensional CT provides the urologist with an interactive road map of the relationships among the tumor, the major vessels, and the collecting system. This information is particularly critical if the tumor extends into the inferior vena cava and if nephron-sparing surgery is being planned.
To evaluate the accuracy of ultrasonography in diagnosing fatty infiltration of the liver (FIL), the authors compared gray-scale B-mode ultrasonography and unenhanced computed tomographic (CT) liver images in a study of 47 patients. The CT scans, which served as the diagnostic standard, were classified as normal, Grade 1 (mild FIL), Grade 2 (moderate FIL), and Grade 3 (severe FIL). Applying predetermined sonographic textural criteria, two experienced radiologists independently graded each ultrasound study for the presence and severity of FIL. The overall accuracy of ultrasonography in detecting FIL was 85 per cent, with 100 per cent sensitivity and 56 per cent specificity. The sonographic/CT correlation in grading the severity of FIL was particularly good for Grade 2 and Grade 3 FIL. Ultrasound is a sensitive and reasonably accurate diagnostic tool in assessing fatty infiltration of the liver.
The measured radiation dose to the phantom was identical for all pitch selections on the multislice helical CT system we tested. This unexpected result was because of an automatic proportionate increase in the tube current when the pitch selection was increased. Radiologists and physicists should exercise caution when extrapolating dose reduction strategies from single-slice to multislice helical CT systems, and they must acquire a detailed understanding of the multislice helical CT scanner of their chosen manufacturer.
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