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J F Platt

Publications and source records attributed to J F Platt.

61 records · Page 4Linked to original sources
PubMed1988

Intraoperative spinal sonography in the evaluation of intramedullary tumors.

Seventeen intraoperative spinal sonographic examinations were performed in 14 patients with intramedullary spinal cord neoplasms. Results of the ultrasound exams were correlated with preoperative imaging studies, surgical findings, and histopathologic analysis of the tumors. Intraoperative spinal sonography accurately localized the intramedullary tumors, often revealing the need for extension of the initial laminectomy. The neoplasms appeared as expansile echogenic masses, with cystic components in over half. Ultrasound was as accurate as preoperative imaging in the evaluation of solid neoplasms, and was superior to computed tomography (CT) and magnetic resonance imaging (MRI) for delineating the cystic components of neoplasms. Intraoperative sonography should be used routinely in all surgical cases of intramedullary spinal cord neoplasms.

Adolescent↗
PubMed1987

The accuracy of CT in the staging of carcinoma of the prostate.

Previous studies have reported the accuracy of CT in distinguishing stages of prostatic carcinoma, but they lack uniform surgical proof of histopathologic stage. We evaluated CT scans in 32 patients who underwent radical prostatectomy to assess its role in the preoperative staging of prostatic carcinoma. Two experienced radiologists blindly interpreted CT scans of the pelvis; they looked for evidence of tumor beyond the prostatic capsule and involvement of the seminal vesicles (stage C) or involvement of pelvic lymph nodes (stage D). Sixty-four interpretations in 32 patients yielded a specificity of 75% for predicting stages A or B disease (local disease), a sensitivity of 50% for the prediction of stages C or D, and an overall accuracy of staging of 67%. Interpretation errors were due to an inability to detect lymph node metastases, errors in evaluating the seminal vesicles, and errors in interpreting densities surrounding the prostate gland. Our data suggest that CT should not be used to influence decisions concerning surgical vs nonsurgical treatment in patients with clinically staged local disease and is only useful when unsuspected metastatic nodal disease is detected.

Diagnostic Errors↗
PubMed1987

CT evaluation of mediastinal lymph nodes in lung cancer: influence of the lobar site of the primary neoplasm.

Previous reports have shown differences in the ability of CT to detect mediastinal lymph nodes, depending on the precise mediastinal location of the nodes. Poorest correlation between findings on CT and findings at autopsy has been described for left-sided lymph nodes, particularly those in the left peribronchial region (American Thoracic Society node station 10L), suggesting that cancers of the left lung might be less well staged by CT than cancers of the right lung. The relationship between the accuracy of mediastinal lymph node staging and the location of the primary lung cancer was examined in a retrospective study. In 103 patients with non-small-cell bronchogenic carcinoma who had preoperative CT evaluation of the mediastinum, the accuracy of preoperative staging was 81% for tumors of the right lung (70 patients) and 97% for tumors of the left lung (33 patients). The conclusion is that cancers of the left lung are staged at least as accurately as cancers of the right lung, despite the fact that left-sided mediastinal nodes are depicted more poorly on CT. Subcarinal and crossover (contralateral) nodal metastases and a low prevalence of metastasis involving only region 10L were the most important factors minimizing staging differences based on the site of the primary tumor.

Humans↗
PubMedDate not supplied

CT of parapelvic cystic renal cell carcinoma.

Parapelvic renal cysts are benign ubiquitous lesions of the renal sinus frequently demonstrated on CT and ultrasonography. Occasionally a renal parenchymal mass will grow so that its epicenter is within the renal sinus. We report two cases of surgically proven cystic renal cell carcinoma centered in the renal sinus with no apparent connection to the renal parenchyma. Cystic renal cell carcinoma must be excluded whenever a parapelvic cyst with atypical features is encountered on cross-sectional imaging studies.

Adult↗
PubMedDate not supplied

Difference in global hepatic enhancement assessed by dynamic CT in normal subjects and patients with hepatic metastases.

PURPOSE: Our goal was to determine if there are differences in liver densitometry parameters using helical CT between normal subjects and subjects with liver metastases. METHOD: One-hundred fifty subjects (64 with normal livers and 86 with CT-visible hepatic metastases) underwent dual phase helical scanning of the liver. Images were obtained in the "arterial" (early) and "venous" (late) phases of hepatic enhancement. Densitometry measurements were obtained from the liver (distinct from obvious lesions or vessels) and aorta at 25, 40, 75, and 90 s. Enhancement values at the same time points were calculated in 73 subjects in whom noncontrast images of the liver were available. A peak liver densitometry value was also determined. Several ratios were determined for each time point: the liver/aortic ratio (L/A), liver/liver peak ratio (L/P), liver enhancement/aortic enhancement ratio (LE/AE), and liver enhancement/liver peak enhancement ratio (LE/LPE). The degree of tumor burden in the hepatic metastatic group was assessed in each case. RESULTS: Values for L/A, L/P, LE/AE, and LE/LPE at 25 and 40 s were significantly (p < 0.05) higher in the liver metastases group than the normal liver group. Enhancement ratios were even more elevated in breast cancer, which can have hypervascular metastases. These CT parameters did not show significant differences when analyzed according to the degree of hepatic metastatic tumor burden. All densitometry parameters and ratios obtained at 75 and 90 s were not significantly different between the two groups. CONCLUSION: In the early phase of bolus intravenous contrast agent administration, the visually normal portion of the liver parenchyma in patients with hepatic metastases enhances to a greater degree than the liver in normal subjects. This may reflect generalized increased hepatic arterial flow in tumor-bearing livers and has the potential to increase the sensitivity of CT for detection of hepatic metastases.

Absorptiometry, Photon↗