High resolution radiography of cadaveric kidneys: unraveling the mystery of Randall's plaque formation.

PURPOSE: We used high resolution radiography to identify and characterize Randall's plaques in cadaveric kidneys. MATERIALS AND METHODS: A total of 50 consecutive sets of cadaveric kidneys was fixed, bivalved and imaged with micro-focal spot magnification radiography. Papillary calcifications were identified, localized and processed for light microscopy. Special immunohistochemical stains were implemented to aid localization of ectopic calcifications. Patient medical records and autopsy results were retrospectively evaluated and correlated with radiographic papillary calcifications. RESULTS: Of the 92 renal units with complete data 52 (57%) had radiographic evidence of renal medullary calcifications consistent with Randall's plaques. Unlike the original description of this condition, calcifications extended deep into the papilla. A history of hypertension was the only clinical parameter correlating with papillary calcifications. Calcium deposition was localized to the basement membrane of collecting tubules and vasa recta, and papillary interstitium. CONCLUSIONS: Randall's plaques are not merely subepithelial deposits. Rather, they appear to extend deep within the papilla, and are intimately associated with collecting tubules and vasa recta. An association between papillary calcifications and urinary stone formation has yet to be proved but is under investigation.

Diagnosis and staging of gastric cancer.

The biphasic upper gastrointestinal examination using barium and gas distention of the stomach is approximately as accurate as endoscopy in the detection of gastric cancer. Endoscopy allows biopsy of suspicious lesions but is more invasive and costly. The barium examination can reliably differentiate gastric ulcers into three categories: benign, malignant, and equivocal. The radiographic findings in gastric carcinoma are described in detail. Staging of gastric cancer is limited by the inability of imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) to detect tumor in normal size lymph nodes. Determination of the presence or absence of local invasion is also difficult in many cases. CT and MRI are effective but imperfect tools for the detection of liver metastasis. Technique and pitfalls in the use of CT and MR in staging gastric carcinoma are emphasized.

CT diagnosis of blunt pancreatic trauma: importance of detecting fluid between the pancreas and the splenic vein.

OBJECTIVE: The purpose of this study was to determine the value of detecting fluid between the splenic vein and the pancreas on CT scans in the diagnosis of pancreatic injury after blunt abdominal trauma. MATERIALS AND METHODS: We retrospectively reviewed the abdominal CT scans of 10 patients with surgical- or autopsy-proved pancreatic injury after blunt abdominal trauma. The finding of fluid interdigitating between the pancreas and the splenic vein was then studied along with the reported CT features of pancreatic injury. These included intraperitoneal fluid, fluid in the lesser sac, extraperitoneal fluid, pancreatic edema or hematoma, and thickening of the anterior renal fascia. RESULTS: The CT scans of all 10 patients reviewed showed abnormalities suggesting pancreatic injury. Only 40% of patients showed all of the findings reported in the literature. Fluid interdigitating between the splenic vein and the pancreatic parenchyma was seen on CT scans in 90%. CONCLUSION: Our experience suggests that fluid between the splenic vein and the pancreas is a helpful CT finding for the diagnosis of pancreatic injury after blunt abdominal trauma. This finding was easy to recognize and in the proper clinical setting directs attention to additional subtle findings of pancreatic injury.

Radiation dose to positron emission tomography technologists during quantitative versus qualitative studies.

Positron emission tomography technologists were monitored with thermoluminescent dosimeters (TLDs) during qualitative and quantitative studies. Doses to technologists during specific tasks were also measured. The technologists received at least twice as much radiation during the quantitative as the qualitative studies. The average dose per study for qualitative studies was 0.017 mSv (1.7 mrem) shallow and 0.014 mSv (1.4 mrem) deep. The average dose per study for the quantitative studies was 0.05 mSv (5 mrem) shallow and 0.04 mSv (4 mrem) deep. The average dose per study was based on the TLD dose accumulated over studies conducted over four 2-mo and one 1-mo intervals. The dose incurred by the technologists each time they drew a radioactive dose was 0.002 mSv (0.2 mrem) shallow and 0.001 mSv (0.1 mrem) deep. The doses received during injection were 0.014 mSv (1.4 mrem) shallow and 0.007 mSv (0.7 mrem) deep. Doses received during blood sampling were 0.016 mSv (1.6 mrem) shallow and 0.014 mSv (1.4 mrem) deep. During quantitative studies, the technologist received a much greater dose than during its qualitative counterpart due to the blood sampling process and increased time in the room with the radioactive patient.

Comparison of the intrasubject repeatability of auditory brain stem and middle latency responses elicited in young children.

The auditory brain stem response (ABR) and middle latency response (MLR) were studied in 48 young children (96 ears). The responses were elicited using low intensity stimuli (30-dB nHL clicks) and simultaneously were recorded on a dual time base. Both the ABR and MLR were elicited in 70 ears. In 12 ears, just one response was recorded (ABR in eight ears and the MLR in four ears). In 14 ears, neither response was recorded. Test-retest analysis on the same subject demonstrated that the ABR was more repeatable and easier to identify than the MLR. The test-retest difference was determined for the amplitude and latency of the ABR and MLR waveforms. The test-retest latency difference for wave Pa was found to be 3.6 times larger than for wave V. The normalized test-retest amplitude difference for P phi-Na, Na-Pa, and Pa-Nb was found to be two to three times larger than for wave V. These data support the conclusion that the ABR, rather than the MLR, should be used to measure hearing in young children. The authors also advocate using minimal high pass (HP) filtering when recording the ABR in a sedated or sleeping child. Muscle artifact was not found to be a problem. The authors suggest the use of minimal HP filtering so that phase-shift distortion is minimized and a larger response amplitude can be recorded.

Electroacoustic calibration for sound field warble tone thresholds.

Walker, Dillon, and Byrne (1984) suggested reference equivalent threshold sound pressure levels (RETSPLs) for warble tones with specific modulation parameter values audited from a test position at the critical distance in a semireverberant sound field. This study evaluated these RETSPLs in two typical audiometric rooms and with typically encountered FM tones. Thresholds were measured under earphones and in two sound fields for 6-11 normal hearers at six test frequencies. Results indicated that there was a small but statistically significant difference between earphone and sound field thresholds in 4 of 24 comparisons. However, in both sound fields, 99% of the sound field thresholds were within 10 dB of the earphone thresholds. It is concluded that these RETSPLs are appropriate for electroacoustic calibration of sound field warble tones similar to those used in this study.