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Stuart G Silverman

Publications and source records attributed to Stuart G Silverman.

15 recordsLinked to original sources
PubMed2003

Hypothesis testing I: proportions.

Statistical inference involves two analysis methods: estimation and hypothesis testing, the latter of which is the subject of this article. Specifically, Z tests of proportion are highlighted and illustrated with imaging data from two previously published clinical studies. First, to evaluate the relationship between nonenhanced computed tomographic (CT) findings and clinical outcome, the authors demonstrate the use of the one-sample Z test in a retrospective study performed with patients who had ureteral calculi. Second, the authors use the two-sample Z test to differentiate between primary and metastatic ovarian neoplasms in the diagnosis and staging of ovarian cancer. These data are based on a subset of cases from a multiinstitutional ovarian cancer trial conducted by the Radiologic Diagnostic Oncology Group, in which the roles of CT, magnetic resonance imaging, and ultrasonography (US) were evaluated. The statistical formulas used for these analyses are explained and demonstrated. These methods may enable systematic analysis of proportions and may be applied to many other radiologic investigations.

Diagnostic Imaging↗
PubMed2003

Preoperative liver donor evaluation: Imaging and pitfalls.

This article discusses the rationale behind living (related) donor liver transplantation, the role of imaging in the preoperative evaluation of the potential donor, and the currently available imaging modalities for fulfilling this task. Furthermore, the normal hepatic vascular and biliary anatomy, as seen on imaging, is reviewed and the most common anomalies are highlighted. Finally, critical concepts in the diagnostic evaluation of a donor are discussed with special emphasis on how to accurately measure liver volumes.

Humans↗
PubMed2003

Pseudomesotheliomatous angiosarcoma of the chest wall and pleura.

Angiosarcoma is a rare soft tissue sarcoma that usually occurs in deep soft tissues, breast, spleen, liver, and bone. Primary thoracic parietal localization of angiosarcoma is rare and prognosis is poor. In this report, we present the CT and PET features of a patient with pseudomesotheliomatous angiosarcoma of the chest wall and pleura, which, to the best of our knowledge, have not previously been described.

Aged↗
PubMed2003

Correlation and simple linear regression.

In this tutorial article, the concepts of correlation and regression are reviewed and demonstrated. The authors review and compare two correlation coefficients, the Pearson correlation coefficient and the Spearman rho, for measuring linear and nonlinear relationships between two continuous variables. In the case of measuring the linear relationship between a predictor and an outcome variable, simple linear regression analysis is conducted. These statistical concepts are illustrated by using a data set from published literature to assess a computed tomography-guided interventional technique. These statistical methods are important for exploring the relationships between variables and can be applied to many radiologic studies.

Factor Analysis, Statistical↗
PubMed2003

Image-guided tumor ablation: proposal for standardization of terms and reporting criteria.

The field of image-guided tumor ablation requires standardization of terms and reporting criteria to facilitate effective communication of ideas and appropriate comparison between treatments with different technologies, such as chemical ablation (ethanol or acetic acid) and thermal therapies, such as radiofrequency, laser, microwave, ultrasound, and cryoablation. On the basis of this premise, a working committee was established with the goal of producing a proposal on such standardization. The intent of the Working Group is to provide a framework that will facilitate the clearest communication between investigators and will provide the greatest flexibility in comparisons between the many new, exciting, and emerging technologies. The members of the Working Group now propose a vehicle for reporting the various aspects of image-guided ablation therapy, including classifications of therapies and procedures, appropriate descriptors of image guidance, and terms to define imaging and pathologic findings. Methods for standardizing the reporting of follow-up findings and complications and other important aspects that require attention when reporting clinical results are addressed. It is the group's hope and intention that adherence to the recommendations of this proposal will facilitate achievement of the group's main objective: improved precision and communication in this field that lead to more accurate comparison of technologies and results and ultimately to improved patient outcomes.

Catheter Ablation↗
PubMed2003

Percutaneous biopsy of renal masses: sensitivity and negative predictive value stratified by clinical setting and size of masses.

OBJECTIVE: The purpose of our retrospective study was to evaluate the sensitivity and negative predictive value of percutaneous biopsy of renal masses stratified by clinical setting and the size of the mass. MATERIALS AND METHODS: We categorized 115 consecutive percutaneous biopsies of renal masses in 113 patients into four clinical settings and three groups of mass sizes. The sensitivity and negative predictive value were computed (with 95% confidence intervals [CI]) for each clinical setting and for each size group. RESULTS: For all procedures (n = 115), the sensitivity and negative predictive value were 90% (95% CI, 81-95%) and 64% (95% CI, 44-81%), respectively. For patients with a known malignancy who presented with a renal mass (n = 55), the sensitivity and negative predictive value were 90% (95% CI, 78-96%) and 38% (95% CI, 10-74%), respectively. For patients with no known malignancy and suspected unresectable tumor (n = 36), the sensitivity and negative predictive value were 92% (95% CI, 76-98%) and 0%, respectively. For patients with no known malignancy who presented with a cystic mass (n = 16), the sensitivity and negative predictive value were 33% (95% CI, 2-87%) and 87% (95% CI, 58-98%), respectively. For patients who were not surgical candidates with a renal cell carcinoma (n = 8) that was thought to be resectable, both the sensitivity and negative predictive value were 100%. For masses 3 cm and less (n = 31), the sensitivity and negative predictive value were 84% (95% CI, 63-95%) and 60% (95% CI, 27-86%), respectively. For masses between 4 and 6 cm (n = 42), the sensitivity and negative predictive value were 97% (95% CI, 83-100%) and 89% (95% CI, 51-99%), respectively. For masses greater than 6 cm (n = 42), the sensitivity and negative predictive value were 87% (95% CI, 71-95%) and 44% (95% CI, 15-77%), respectively. CONCLUSION: Percutaneous renal mass biopsy has a high sensitivity in three clinical settings: patients with a known malignancy, patients with no known malignancy and suspected unresectable tumor, and nonsurgical patients with a mass suspected to be a resectable renal cell carcinoma. Negative results in small (< or = 3 cm) and large (> 6 cm) masses should be viewed with caution.

Aged↗
PubMed2003

Macrocystic serous adenoma of the pancreas: radiologic-pathologic correlation.

OBJECTIVE: Macrocystic serous adenoma is a rare benign pancreatic neoplasm, recently described in the pathology literature. We describe the CT and MR imaging features in a series of five consecutive pathologically proven cases. MATERIALS AND METHODS: Of seven cases fulfilling the pathology criteria for macrocystic serous adenoma over an 11-year period, five patients underwent preoperative CT and MR imaging at our institution. In addition to the clinical presentation and pathologic features of the tumor, the following CT and MR imaging features were reviewed: size and location; wall thickness; internal septations; and presence of mural nodules, papillary projections, or calcifications. RESULTS: All patients but one were women (age range, 36-78 years; mean age, 48.6 years). The sizes of the tumors ranged from 1.5 to 5.0 cm (mean, 3.1 cm). Three (60%) of five tumors were located in the pancreatic head. The wall measured less than 2 mm in four lesions and 4 mm in one. No mural nodules, papillary projections, or calcifications were present. Lesions were unilocular (n = 3) or bilocular (n = 2). Excellent correlation of imaging features with gross pathology was observed. CONCLUSION: On CT and MR imaging, the macrocystic variant of serous adenoma typically appears as a small (< 5 cm), uni- or bilocular cyst with a thin (< 2 mm) wall that lacks mural nodules or calcifications. The imaging appearance of macrocystic serous adenoma is distinctly different from that of microcystic serous cystadenoma, but the imaging appearance of macrocystic serous adenoma is indistinguishable from mucinous cystadenoma and cystadenocarcinoma of the pancreas.

Cystadenoma, Serous↗
PubMed2003

MR imaging features of solid pseudopapillary tumor of the pancreas in adult and pediatric patients.

OBJECTIVE: This study was conducted to describe the MR imaging features of solid pseudopapillary tumor of the pancreas. CONCLUSION: Solid pseudopapillary tumor of the pancreas, a tumor typically seen in young women, is a large, well-defined, encapsulated lesion with heterogeneous high or low signal intensity on T1-weighted, heterogeneous high signal intensity on T2-weighted, and early peripheral heterogeneous enhancement with progressive fill-in on gadolinium-enhanced dynamic MR imaging. These features help differentiate this rare tumor from other pancreatic neoplasms.

Adolescent↗
PubMed2002

Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors.

BACKGROUND: Constitutive activation of KIT receptor tyrosine kinase is critical in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate, a selective tyrosine kinase inhibitor, has been shown in preclinical models and preliminary clinical studies to have activity against such tumors. METHODS: We conducted an open-label, randomized, multicenter trial to evaluate the activity of imatinib in patients with advanced gastrointestinal stromal tumor. We assessed antitumor response and the safety and tolerability of the drug. Pharmacokinetics were assessed in a subgroup of patients. RESULTS: A total of 147 patients were randomly assigned to receive 400 mg or 600 mg of imatinib daily. Overall, 79 patients (53.7 percent) had a partial response, 41 patients (27.9 percent) had stable disease, and for technical reasons, response could not be evaluated in 7 patients (4.8 percent). No patient had a complete response to the treatment. The median duration of response had not been reached after a median follow-up of 24 weeks after the onset of response. Early resistance to imatinib was noted in 20 patients (13.6 percent). Therapy was well tolerated, although mild-to-moderate edema, diarrhea, and fatigue were common. Gastrointestinal or intraabdominal hemorrhage occurred in approximately 5 percent of patients. There were no significant differences in toxic effects or response between the two doses. Imatinib was well absorbed, with pharmacokinetics similar to those reported in patients with chronic myeloid leukemia. CONCLUSIONS: Imatinib induced a sustained objective response in more than half of patients with an advanced unresectable or metastatic gastrointestinal stromal tumor. Inhibition of the KIT signal-transduction pathway is a promising treatment for advanced gastrointestinal stromal tumors, which resist conventional chemotherapy.

Adolescent↗
PubMed2002

Interventional radiology procedures in the liver. Biopsy, drainage, and ablation.

Radiologically guided interventional procedures in the liver have continually increased, in number and variety, over the years. Factors promoting these advances include new technology, innovative ideas, and growing acceptance by clinicians and patients. Percutaneous biopsy and drainage procedures are firmly established techniques with low complication rates. Ablation by injected substances is useful for treating certain tumor types. The most exciting development is the introduction of percutaneous thermal techniques for tumor ablation. Although more experience is needed to optimize the use of focal thermal ablation, early results seem promising.

Biopsy, Needle↗
PubMed2002

Multi-detector row CT urography: comparison of strategies for depicting the normal urinary collecting system.

PURPOSE: To evaluate several protocols for depiction of the urinary collecting system with multi-detector row computed tomographic (CT) urography. MATERIALS AND METHODS: Fifty-one patients with hematuria or a suspicious renal mass underwent CT urography, during which thinly collimated (1-mm) pyelographic phase scanning was performed 8-10 minutes after contrast medium administration. Patients were examined while prone only (n = 17) and while both prone and supine (n = 17) after a 250-mL infusion of normal saline. Each collecting system and ureter was divided into six segments that were assigned opacification scores. All acquisition techniques were compared, and the highest-scoring technique was compared with that in 17 patients who underwent conventional intravenous urography (IVU). Three reconstruction techniques (transverse, coronal, and maximal intensity projection) were also compared. Stratified analysis was performed with the paired two-tailed Student t test to compare opacification scores for both the acquisition techniques and display methods, both individually and in all possible combinations. RESULTS: CT urography with supplemental saline administration, performed with the patient prone or supine, significantly improved mean opacification scores in the distal ureters (right, P =.004; left, P =.006). With this technique, CT urography produced a mean opacification score that was not significantly different from that with IVU in 11 of 12 segments and was significantly better than that with IVU in one of 12 segments (lower left ureter). Mean opacification scores obtained with transverse or coronal displays were equal to or higher than those obtained with maximum intensity projection reconstructions in all segments. CONCLUSION: CT urography with a multi-detector row scanner and supplemental infusion of normal saline reliably displays the opacified urinary collecting system.

Female↗
PubMed2002

Pseudoenhancement of simulated renal cysts in a phantom using different multidetector CT scanners.

OBJECTIVE: We undertook this study to determine whether pseudoenhancement of renal cysts occurs on scans obtained with multidetector CT (MDCT) scanners and whether the effect is influenced by scanning parameters. MATERIALS AND METHODS: A kidney phantom with varying attenuation was created to simulate different levels of renal parenchymal enhancement (150 and 250 H). Two water-filled cylinders simulating renal cysts-one with a 5-mm diameter and one with a 15-mm diameter-were suspended in the "kidney." After validating the pseudoenhancement effect produced in our phantom model with a single-detector helical CT scanner, we investigated the effect with matrix array and adaptive array MDCT scanners using detector configurations of 1.25 and 2.5 mm and beam pitches of 0.75:1.0 and 1.5:1.0 at an effective reconstructed slice thickness of approximately 3 mm. Three sets of experiments were performed at each setting, and mean cyst density was measured. Data were statistically analyzed using the Student's t test and multiple logistic regression analysis when appropriate. RESULTS: Although pseudoenhancement was observed with MDCT scanners, the effect was statistically significant only for scans depicting the smaller cyst at a background renal density of 250 H on the matrix array MDCT. Modulation of scanning parameters did not alter these findings. Pseudoenhancement was significantly higher with the matrix array MDCT scanner than with the adaptive array MDCT scanner (p < 0.05). CONCLUSION: In our phantom model, high levels of renal enhancement produced pseudoenhancement in small renal cysts with different models of MDCT scanners, irrespective of pitch or detector configuration.

Humans↗