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Biomedical subjects

S G Silverman

Publications and source records attributed to S G Silverman.

At least 19 recordsLinked to original sources
PubMed2000

Staging of advanced ovarian cancer: comparison of imaging modalities--report from the Radiological Diagnostic Oncology Group.

PURPOSE: To compare ultrasonography (US), magnetic resonance (MR) imaging, and computed tomography (CT) for diagnosing and staging advanced ovarian cancer. MATERIALS AND METHODS: US, CT, and MR imaging were performed in 280 patients. Images were read by three radiologists from each of the five hospitals. Image analysis included determination of malignancy within the peritoneum (11 sites), lymph nodes (10 sites), and hepatic parenchyma. The standard of reference was based on surgical and histopathologic findings. Statistical methods used were receiver operating characteristic (ROC) curve analysis, pairwise comparison of areas under the ROC curves (A(z)), analysis of sensitivity and specificity pairs, and assessment of agreement between the degree of suspicion and standard of reference. RESULTS: There were 118 patients with malignant tumors; 73 (62%) had stage III or IV disease. Metastases were found in the peritoneum in 70 (59%), nodes in 20 (17%), and liver in seven (6%) cases. In the peritoneum, MR imaging and CT (A(z) = 0.96 for both) were more accurate than US (A(z) = 0.86), especially in the subdiaphragmatic spaces and hepatic surfaces. MR imaging and CT were more sensitive than US (95%, 92%, and 69%, respectively) for peritoneal metastases. MR imaging was more accurate than CT for detection of lymph node metastases (A(z) = 0.76 vs 0.57, P =.04). In the liver, the A(z) values for the three modalities were 0.77-0.94. CONCLUSION: CT and MR imaging are equally accurate, and either modality can be used to stage advanced ovarian cancer.

Adult↗
PubMed2000

Intracavitary urokinase for enhancement of percutaneous abscess drainage: phase II trial.

OBJECTIVE: To evaluate the effectiveness of urokinase as an abscess-cavity irrigant during percutaneous abscess drainage. SUBJECTS AND METHODS: In a prospective study, approved by the Food and Drug Administration and the review board at our institution, urokinase and saline were used as abscess-cavity irrigants. In the study group of 42 patients, half the patients were randomly placed into the urokinase group and the other half were placed into the control saline group. Doses used varied with the size of the abscess. Data collected from patient charts were evaluated with standard statistical methods. RESULTS: The results indicate definite benefits of the urokinase treatment. The length of stay (p = 0.0025) and treatment costs (p = 0.0021) were significantly less for the urokinase group. Other clinical parameters, including the febrile course, elevated WBC, and days of drainage, trended in a favorable fashion. CONCLUSION: Urokinase injected intracavitarily is an effective technique for shortening the treatment time and improves the clinical course for patients treated with percutaneous drainage techniques.

Abscess↗
PubMed1999

Diagnosis and staging of ovarian cancer: comparative values of Doppler and conventional US, CT, and MR imaging correlated with surgery and histopathologic analysis--report of the Radiology Diagnostic Oncology Group.

PURPOSE: To determine the optimal imaging modality for diagnosis and staging of ovarian cancer. MATERIALS AND METHODS: Two hundred eighty women suspected to have ovarian cancer were enrolled in a prospective study before surgery. Doppler ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging were used to evaluate the mass; conventional US, CT, and MR imaging were used to stage spread. RESULTS: All three modalities had high accuracy (0.91) for the overall diagnosis of malignancy. In the ovaries, the accuracy of MR imaging (0.91) was higher than that of CT and significantly higher than that of Doppler US (0.78). In the extraovarian pelvis and in the abdomen, conventional US, CT, and MR imaging had similar accuracies (0.87-0.95). In differentiation of disease confined to the pelvis from abdominal spread, the specificity of conventional US (96%) was higher than that of CT and significantly higher than that of MR imaging (88%), whereas the sensitivities of MR imaging (98%) and CT (92%) were significantly higher than that of conventional US (75%). CONCLUSION: MR imaging is superior to Doppler US and CT in diagnosis of malignant ovarian masses. There is little variation among conventional US, CT, and MR imaging as regards staging.

Adult↗
PubMed1999

CT fluoroscopy-guided abdominal interventions: techniques, results, and radiation exposure.

PURPOSE: To evaluate the benefits of computed tomographic (CT) fluoroscopy-guided interventions and assess radiation exposures incurred with CT fluoroscopy. MATERIALS AND METHODS: A 6-month period of use of CT fluoroscopy to guide abdominal biopsy procedures and catheter drainage was analyzed. Efficacy measures and needle placement and procedure room times were compared with those of the preceding 6 months during which conventional CT was used. CT fluoroscopic times and estimated radiation exposures were compared for two CT fluoroscopic methods. RESULTS: The sensitivity and negative predictive values for biopsy procedures and the success rate for needle aspiration or catheter drainages for CT fluoroscopy--98%, 86%, and 100%, respectively--were not significantly different from those for conventional CT--95%, 80%, and 97%, respectively. Room time was not reduced significantly, but mean needle placement time for CT fluoroscopy (29 minutes; n = 95) was significantly lower than that for conventional CT (36 minutes; n = 93; P < .005). The mean patient dose index was 74 cGy. Limiting CT fluoroscopy to scanning the needle tip rather than scanning the entire needle pass significantly reduced the dose to the patient and the operator. CONCLUSION: Although CT fluoroscopy is a useful targeting technique, significant radiation exposures may result. Therefore, radiologists need to be aware of different methods of CT fluoroscopic guidance and the factors that contribute to radiation exposure.

Abdomen↗
PubMed1999

Staging of 119 patients with renal cell carcinoma: the yield and cost-effectiveness of pelvic CT.

OBJECTIVE: The goal of this study was to determine the yield and cost-effectiveness of pelvic CT in staging renal cell carcinoma. MATERIALS AND METHODS: The records of 119 patients who underwent preoperative CT of the abdomen and pelvis during a 6-year interval and then underwent partial or radical nephrectomy for renal cell carcinoma were reviewed for CT findings and pathologic stage. Pelvic CT findings were divided into three categories: benign and likely insignificant, benign and likely significant, and probably malignant. The effect of CT findings on further testing and the scheduling of surgery was assessed. An estimate of the cost of pelvic CT scans and other radiologic tests was made using 1997 Medicare reimbursement rates. RESULTS: Total estimated cost of the 119 CT examinations of the pelvis was $40,698 ($342 each). No findings of probable malignancy were identified. In 27 patients, CT showed benign findings; these results did not cause planned surgery to be delayed. Three of these 27 patients underwent further radiologic tests at an estimated total cost of $243. CONCLUSION: CT of the pelvis has a negligible yield in the staging of renal cell carcinoma and should not be routinely performed. The findings on CT of the pelvis did not generate a significant number of other tests.

Carcinoma, Renal Cell↗
PubMed1999

Helical CT of the urinary tract.

The advent of helical CT has changed the practice of uroradiology and has significantly benefited patients. Painful, obstructing ureteral stones can be diagnosed with certainty in less than 1 min without contrast medium. Radiologists can now thoroughly evaluate and characterize small renal masses without fear of skip areas caused by respiratory misregistration. Radiologic evaluation of living potential renal donors, formerly a two- or three-stage procedure, can now be performed in a single visit. Finally, three-dimensional reconstructions allow use of the same data both to diagnose tumors and to plan their resection. Axial or three-dimensional images generated using helical CT will likely be increasingly important in detecting and staging cancer, determining stone composition and appropriate therapy, and evaluating renal artery stenosis.

Adult↗
PubMed1999

MR-guided therapy. Applications in the abdomen.

This article provides an overview of current abdominal interventional applications that use MR imaging guidance and monitoring for diagnostic biopsies, tumor ablations and--owing to the development of new pulse sequences--monitoring the ablation process, and aspiration and drainage of fluid collections. These applications are optimal for patients with lesions that can be localized only by MR imaging or for lesions in suboptimal locations such as the dome of the liver.

Abdomen↗
PubMed1998

Open-configuration MR imaging, intervention, and surgery of the urinary tract.

The open-configuration MR imaging system provides new applications both in diagnosis and in therapy of conditions in the urinary tract. In addition to conventional imaging, the open configuration permits MR imaging of patients in many positions. This has already been shown to be useful in imaging the pelvis during voiding, where a sitting position allows urodynamic evaluation. The lithotomy position can be used for imaging the prostate, which also permits procedural access. The ultimate purpose of the interventional MR imaging suite is to integrate therapeutic tools and techniques with MR imaging. From surgical planning through specialized imaging systems with minimally invasive surgical applications, new methods are being developed and implemented. This new field of image-guided therapy will require extensive clinical development and evaluation for applications in the urinary tract. This will require a large concentrated interdisciplinary effort of surgeons, radiologists, computer scientists, engineers, and physicists. Successful integration of basic research and clinical work will result in a number of cutting-edge technologies with direct clinical application in the urinary tract. Initial projects have included biopsies, endoscopies, and real-time procedural control of high-temperature and cryogenic ablations. It is anticipated that the current surge in image-guided interventions will motivate even more research activity in this field, and will ultimately define the role of MR imaging guidance in urologic intervention and surgery.

Animals↗
PubMed1998

Original smooth receiver operating characteristic curve estimation from continuous data: statistical methods for analyzing the predictive value of spiral CT of ureteral stones.

RATIONALE AND OBJECTIVES: Diagnostic studies such as spiral computed tomography (CT) in patients with obstructing ureteral calculi often necessitate the analysis of continuous test data (e.g., stone sizes). The accuracy of a test can be summarized by using a receiver operating characteristic (ROC) curve. The authors developed and compared three methods for constructing a smooth ROC curve from continuous diagnostic data. MATERIALS AND METHODS: Nonparametric, semiparametric, and parametric smooth ROC curve analyses were applied to data from 100 unenhanced spiral CT scans of patients with proved obstructing ureteral stones. Accuracy in using stone size to predict the need for intervention was evaluated by means of these methods. Characteristics and summary measures of the resulting ROC curves were estimated. RESULTS: All methods fit the data well. The nonparametric method followed the details of the empiric data. The semiparametric and parametric methods yielded similar estimates of the ROC curve parameters. Areas under the ROC curves were 0.807, 0.821, and 0.814 for nonparametric, semiparametric, and parametric methods, respectively, in comparison with 0.811 for the empiric method. CONCLUSION: The parametric method is preferred for constructing a smooth ROC curve with available stone-size data derived from spiral CT. The analyses confirm the predictive value of stone size in determining the need for intervention.

Humans↗
PubMed1998

Multidisciplinary gastrointestinal cancer clinic: abdominal radiologist as active participant.

RATIONALE AND OBJECTIVES: Abdominal radiologists actively participated and provided subspecialty radiologic expertise in a multidisciplinary gastrointestinal cancer clinic that served a tertiary referral center. The purpose of this study was to evaluate the feasibility and nonradiologists' opinions of this new approach to radiologic consultation. MATERIALS AND METHODS: One of four subspecialty-trained abdominal radiologists joined physicians from four other subspecialties in staffing weekly 4-hour clinic sessions. Images were reviewed, opinions on test selection and interventional options rendered, and patients met with when interventional options were considered. Radiologists were compensated a fixed sum for each session. A survey of nonradiologists' opinions about the radiologists' active participation was conducted after 15 months (61 clinic sessions). RESULTS: Abdominal radiologists' active participation was feasible and highly regarded by nonradiologist physicians. Specific benefits cited in the survey included improved interpretation, more efficient use of nonradiologist physician time, and improved rapport between radiologists and nonradiologists. Nonradiologist physicians believed that patient care was improved and that the radiologists' participation should continue. CONCLUSION: The active participation of abdominal radiologists in a multidisciplinary gastrointestinal cancer clinic is feasible and highly regarded by nonradiologists.

Attitude of Health Personnel↗
PubMed1998

Percutaneous abdominal biopsy: cost-identification analysis.

PURPOSE: To determine the difference in cost to providers of percutaneous abdominal biopsy as the first strategy versus surgical biopsy. MATERIALS AND METHODS: Cost of tissue diagnosis determination with percutaneous biopsy as the first strategy in 439 patients with an abdominal mass was estimated. Costs included direct hospital costs and professional costs of initial and repeat biopsy, follow-up imaging and clinic visits, surgical biopsy (when needed), and treatment of complications. The sum of these costs was compared with the estimated cost had the same patients undergone surgical biopsy instead, with no complications or need for follow-up or repeat biopsy. RESULTS: The total estimated cost of percutaneous biopsy as the first strategy ($543,245) was less than the cost had surgical biopsy been used alone ($1,919,867). The average per patient direct hospital cost of percutaneous biopsy ($800) was lower than that of surgical biopsy ($3,419). The average per patient professional cost of percutaneous biopsy ($438) was also lower than that of surgical biopsy ($955). Savings averaged $3,136 per patient, or $1,376,622 for the study period. CONCLUSION: Substantial health care cost savings may result by using a diagnostic algorithm in which percutaneous biopsy is the first strategy for establishment of a diagnosis in patients suspected of having abdominal malignancy.

Abdominal Neoplasms↗
PubMed1998

Negative predictive value of imaging-guided abdominal biopsy results: cytologic classification and implications for patient management.

OBJECTIVE: Our purpose was to assess the negative predictive value of imaging-guided abdominal biopsy results and correlate it with cytology classification, lesion size, needle gauge, and cancer history. MATERIALS AND METHODS: A retrospective study was performed of 100 patients with proven diagnoses who had undergone imaging-guided abdominal biopsies showing no cells that were malignant or suspicious for malignancy. Specimens were classified as normal or benign, nondiagnostic, or atypical. Negative predictive value was calculated for each cytologic category, lesion size, needle gauge, and cancer history. Logistic regression analysis was performed to allow us to identify predictors of false-negative results. RESULTS: Overall negative predictive value was 67%. Other negative predictive values were normal or benign result, 78%; nondiagnostic result, 66%; and atypical result, 29%. Negative predictive value was greater when the lesion was large (> or =3 cm) (p = .031). Logistic regression analysis allowed us to predict a 9.3% chance of a false-negative result for a specimen of normal or benign cytology that was taken from a large lesion in a patient with no cancer history but an 87% chance of a false-negative when a specimen of atypical cytology was taken from a small (<3 cm) lesion in a patient with a cancer history. CONCLUSION: Imaging-guided abdominal biopsy specimens containing atypical cells should be viewed with caution. In patients without cancer, if a lesion is large and the specimen contains normal target organ or benign cells, the likelihood of a false-negative result may be low enough that imaging surveillance at appropriate intervals may be sufficient.

Abdominal Neoplasms↗
PubMed1998

Unenhanced helical CT of ureteral stones: a replacement for excretory urography in planning treatment.

OBJECTIVE: The purpose of this study was to determine whether unenhanced helical CT alone can be used for diagnosis and treatment planning of patients with obstructing ureteral stones. MATERIALS AND METHODS: Medical records of 100 patients with ureteral stones and a clearly discernible clinical outcome who had undergone unenhanced helical CT were reviewed to determine the number of urography procedures and results of excretory urograms performed within 72 hr of helical CT. CT scans were then reviewed by two radiologists for six findings: in-plane stone diameter, z-axis stone diameter, location of stone, periureteral stranding, hydronephrosis, and perinephric fluid. Seventy-one patients passed stones spontaneously, and 29 patients required intervention including basket retrieval, extracorporeal shock-wave lithotripsy, laser lithotripsy, or a combination of the three treatments. Data were analyzed to determine those findings that correlated with the need for intervention. RESULTS: Five excretory urograms were obtained, all of which agreed with findings revealed by CT. Excretory urography added no information. CT findings of in-plane diameter (p < .001), z -axis diameter (p < .001), and location of stone (p = .003) all significantly correlated with the need for intervention. CONCLUSION: Helical CT can be used in place of excretory urography to plan treatment of patients with flank pain caused by obstructing ureteral stones. Stones that are larger than 5 mm, located within the proximal two thirds of the ureter, and seen on two or more consecutive CT images are more likely to require endoscopic removal, lithotripsy, or both.

Adult↗
PubMed1997

[Design, clinical suitability and future aspects of a 0.5 T MRI special system for interventional use].

PURPOSE: To develop a superconducting magnetic resonance (MR) imager that provides direct access to the patient and permits interactive MR-guided interventional procedures. MATERIALS AND METHODS: A 0.5-T superconducting magnet that allows a region of vertical access to the patient was designed and constructed. This magnet was integrated with newly designed shielded gradient coils, flexible surface coils, nonmagnetic displays, position-monitoring probes and device-tracking instrumentation. RESULTS: The magnet homogeneity was 12.3 ppm or better, and the gradient field was linear to within 1% over an imaging region of 30 cm in diameter. The signal-to-noise ratio was 10% higher than in a comparable 0.5-T superconducting imager. Images were obtained in several anatomic regions with use of routine pulse sequences. Interactive image plane selection and near real-time imaging, with use of fast gradient-recalled echo sequences were demonstrated at a rate of one image every 1.5 s. More than 240 procedures (including open brain surgery) have been successfully performed within this environment. CONCLUSIONS: MR-guided interventional and surgical procedures can be performed with full patient access using an open-configuration, superconducting MR magnet with near real-time imaging and interactive image plane control.

Endoscopes↗