PubMed Health⌕ Search

Biomedical subjects

R J Wechsler

Publications and source records attributed to R J Wechsler.

At least 19 recordsLinked to original sources
PubMed1998

Helical CT of calcaneal fractures: technique and imaging features.

Since the degree of comminution, fracture alignment, and articular congruity of intra-articular calcaneal fractures are important determinants in surgical treatment and patient prognosis, we review helical computed tomographic (CT) technique and features for detecting and assessing the extent of acute calcaneal fractures. Helical CT can be used to classify these fractures and facilitate the surgeon's understanding of the anatomy and position of the fracture components in all orthogonal planes independently of the patient's condition, foot placement in the CT gantry, or other injuries.

Calcaneus↗
PubMed1998

Comparison of Doppler US and CT angiography for evaluation of renal artery stenosis.

RATIONALE AND OBJECTIVES: The authors compared Doppler ultrasound (US) with computed tomographic (CT) angiography in the evaluation of stenosis of the main renal artery. MATERIALS AND METHODS: Fifty-six patients who had undergone conventional angiography of the renal arteries participated in a prospective comparison of Doppler US (45 patients) and CT angiography (52 patients). US evaluation included both the main renal artery and segmental renal arteries. RESULTS: There were 27 main renal arteries with at least 50% stenosis in 20 patients. In 36 patients, there was no significant stenosis. All cases of main renal artery stenosis detected with Doppler US of the segmental arteries were also identified with Doppler US of the main renal artery. The by-artery sensitivity (63%) of US of the main renal artery was greater than that (33%) of US of the segmental arteries. CT angiography was more sensitive (96%) than Doppler US (63%) in the detection of stenosis, but the specificity of CT (88%) was similar to that of US (89%). The difference in the area under the receiver operating characteristic curve (AUC) between CT (AUC = 0.94) and US (AUC = 0.82) was statistically significant (P = .038). CONCLUSION: Doppler US of the main renal artery is more sensitive than Doppler US of segmental arteries in the detection of stenosis. CT angiography is more accurate than Doppler US in the evaluation of renal artery stenosis.

Adult↗
PubMed1997

Helical CT of talar fractures.

Since the degree of comminution, fracture alignment, and articular congruity of talar fractures are important determinants of treatment, we review the helical CT technique for detecting and assessing the extent of acute talar fractures. Helical CT can be used to classify talar neck fractures which often cannot be determined by radiography. It is also useful in detecting posterior process, lateral process, and avulsion fractures, as well as acute osteochondral fractures. Multiplanar CT using 1-mm acquisitions allows optimal evaluation, detects fractures initially missed on radiographs, and determines further extent of fractures.

Adolescent↗
PubMed1997

Biliary-pleural fistulas without biliary obstruction: percutaneous catheter management.

OBJECTIVE: Our purpose was to report the use of percutaneous catheter drainage as a therapeutic option in the management of three patients with biliary-pleural fistulas without biliary obstructions. CONCLUSION: In the proper clinical setting, the CT findings of liver dome laceration or abscess, diaphragm disruption, and pleural effusion should suggest biliary-pleural fistula. Percutaneous catheter management can be curative or serve a temporizing function before surgery.

Adult↗
PubMed1996

Effects of training and experience in interpretation of emergency body CT scans.

PURPOSE: To determine the effects of level of training and other factors on the rate of discrepant interpretation of emergency body computed tomographic (CT) scans by trainees and staff radiologists. MATERIALS AND METHODS: Five hundred ninety-eight consecutive emergency CT studies were prospectively interpreted by radiology residents or board-certified body imaging fellows over a 12-month period. Each interpretation was reviewed within 12 hours by an attending body CT radiologist. Major discrepancies between staff radiologists' and trainees' interpretations were defined and those with the potential to affect immediate patient therapy; minor discrepancies were defined ad those without such potential. The effects on discrepancy rates were examined for abnormal versus normal CT findings and trauma versus nontrauma cases. RESULTS: Major and minor discrepancy rates were 1.2% and 6.5%, respectively, between interpretations made by the trainee and the staff radiologist. Overall, fellows demonstrated statistically significantly lower discrepancy rates than did senior of junior residents (5.9%, 13.7%, and 13.3%, respectively). The discrepancy rate was higher when CT findings were abnormal than when they were normal (13.5% vs 2.6%). There were no differences between discrepancy rates for trauma and nontrauma cases. CONCLUSION: Experience appeared to decrease discrepancy rates. Trainees were more likely to miss findings than to read normal scans as abnormal.

Certification↗
PubMed1996

Incidental pulmonary emboli detected at helical CT: effect on patient care.

PURPOSE: To evaluate incidental pulmonary emboli detected at helical computed tomography (CT) and the effect on patient care. MATERIALS AND METHODS: A computer search of reports from 1,879 consecutive contrast material-enhanced helical CT scans identified 28 cases in which pulmonary emboli were suggested. These 28 scans were rereviewed by three radiologists to confirm intraluminal defects. Six cases were excluded (three because of tumor invasion, two arterial stump thrombi after pneumonectomy, one artifact). In four cases, pulmonary emboli were clinically suspected or diagnosed prior to CT. Pulmonary embolus was not suspected at CT in the remaining 18 patients who constituted the study group. The medical records were reviewed for predisposing factors, suspicion of pulmonary embolism, adjuvant studies, and resultant therapy. RESULTS: All 18 patients in the study group had predisposition for thromboembolic disease. Seven of these patients underwent confirmatory or correlative studies (angiography, radionuclide studies, or autopsy), and four patients had supportive studies documenting deep venous thrombosis. Eleven patients received anticoagulants or caval filter placement as a result of CT findings. CONCLUSION: Incidental pulmonary emboli were detected in approximately 1% of patients who underwent contrast-enhanced CT of the chest. All of these patients were at high risk for emboli. Therapeutic intervention was undertaken in 61% of these patients. While ultimate patient outcome is uncertain, the incidental CT diagnosis of pulmonary emboli appears accurate and affects patient care.

Adult↗
PubMed1996

The relationship of thoracic lymphadenopathy to pulmonary interstitial disease in diffuse and limited systemic sclerosis: CT findings.

OBJECTIVE: Mediastinal lymphadenopathy is frequently associated with interstitial lung disease (ILD) in patients with systemic sclerosis (SSc). This study compared the extent of lymphadenopathy in diffuse and limited SSc with the presence and type of ILD found on CT scans. SUBJECTS AND METHODS: Seventy-three patients with diffuse and limited SSc underwent thoracic CT. The presence of lymphadenopathy was correlated with the frequency and type of ILD. RESULTS: Fifty-eight percent (18/31) of patients with diffuse cutaneous SSc and 40% (17/42) of patients with limited cutaneous SSc had lymphadenopathy. A significant relationship was found between lymphadenopathy and the presence of interstitial disease (p = .0002). Seventy-two percent (18/25) of patients with a ground-glass parenchymal pattern of interstitial disease and 74% (14/19) of patients with a honeycomb pattern had lymphadenopathy. CONCLUSION: Lymphadenopathy is prevalent in patients with SSc and ILD regardless of clinical subtype or interstitial pattern. Lymphadenopathy appears to increase as a function of the profusion rather than the morphology of ILD.

Female↗
PubMed1995

src-family tyrosine kinase p55fgr is expressed in murine splenic B cells and is activated in response to antigen receptor cross-linking.

Stimulation of the B cell Ag receptor (BCR) triggers a complex cascade of intracellular signals that lead to activation, proliferation, and differentiation. One of the earliest and most critical events following Ag receptor cross-linking is the activation of receptor-associated tyrosine kinases, which phosphorylate a variety of substrates involved in transducing signals generated through the receptor. Several tyrosine kinases have been shown to be associated with the BCR, including the src family members Lyn, Fyn, Blk, and Lck and the non-src kinase Syk. Here we describe another src family kinase expressed in B cells, p55fgr. Although previous studies have suggested that Fgr expression in the mouse is restricted to cells of the myeloid lineage, we demonstrate that highly purified murine splenic B cells express the kinase as well. We also show that Fgr, like other B cell kinases, is activated in response to cross-linking of the Ag receptor. Unlike these other kinases, however, Fgr does not appear to be physically associated with the receptor, and does not become activated until several minutes after stimulation. Moreover, we find that Fgr is associated with a distinct set of cellular proteins. On the basis of these studies, we hypothesize that Fgr may play a unique role in the BCR-associated signaling pathway.

Animals↗
PubMed1995

Immature B lymphocytes are deficient in expression of the src-family kinases p59fyn and p55fgr1.

Unlike mature B cells, immature B cells are highly sensitive to tolerance induction and do not proliferate in response to stimulation through their Ag receptors. Our previous studies have suggested that this differential responsiveness is caused by differences in Ag receptor-proximal signaling pathways. Because many of these pathways are regulated by tyrosine phosphorylation, we have compared the expression and activity of tyrosine kinases in immature and mature B cells. Consistent with previous studies, we demonstrate that mature B cells express syk, lyn, blk, hck, and fyn; in addition, we find that they express significant amounts of the src-family kinase p55fgr. Immature B cells from day-3 mouse spleen show similar expression and activity of syk, lyn, blk, and hck. However, these cells have marked deficiencies in fyn and fgr expression. Differential expression of fyn and fgr is also observed in immature cells from the bone marrow, indicating that this phenotype is characteristic of the immature stage of B cell development. High levels of fyn and fgr are detectable in splenic B cells beginning at 4 wk of age, coincident with the appearance of cells that proliferate in response to receptor cross-linking. These observations indicate that expression of the src-family kinases fyn and fgr is regulated developmentally in murine B lymphocytes. Moreover, they suggest that these kinases may be important for mature B cell responses to Ag receptor stimulation, and that their absence may contribute to the unresponsiveness and tolerance susceptibility of immature B cells.

Animals↗
PubMed1995

Threshold selection for CT angiography shaded surface display of the renal arteries.

The purpose of this study was to define objective criteria to calculate a tissue segmentation threshold for shaded surface display (SSD) rendering of the renal arteries with computed tomography angiography. Contrast-enhanced spiral CT scans were obtained through the renal arteries of nine patients. Six sets of SSD images were rendered for each patient with lower threshold values ranging from 80 to 130 Hounsfield units (HU) by increments of 10 HU. Visceral organ enhancement was measured in the aorta, liver, spleen, pancreas, and kidney. The segmentation threshold for each patient was determined by evaluation of the SSD images alone as well as by comparison with conventional arteriograms. The ideal threshold, as shown by comparison with conventional arteriography, was better correlated with a threshold value selected by qualitative evaluation of SSD images alone (rs = .42), than with measured enhancement in visceral organs (rs = -.289 to .009). The degree of stenosis was overestimated in a single renal artery (1 of 18) because of an inappropriate threshold selected by evaluation of the SSD images alone. In comparison with a segmentation threshold calculated from measured enhancement of visceral organs, a segmentation threshold selected by qualitative evaluation of the resulting SSD images is more likely to approximate the ideal threshold. Given the subjective nature of such threshold selection, further evaluation is warranted to determine whether threshold selection may result in inaccurate grading of stenosis.

Adult↗
PubMed1995

Role of thoracoscopy and preoperative localization procedures in the diagnosis and management of pulmonary pathology.

Video-assisted thoracic surgery is an important component of modern thoracic surgery, providing a safe, less invasive alternative to open thoracotomy in the evaluation of pleural, mediastinal, and parenchymal pathology. Advancements in endoscopic techniques and video-optics have permitted greater visualization of the thoracic cavity and allowed limited pulmonary resections with significantly reduced postoperative morbidity. Thoracoscopy is indicated for diagnosis of intrathoracic pathology when usual methods of diagnosis, including fine-needle aspiration and transbronchial biopsy, are inconclusive. The diagnostic accuracy of video-assisted thoracic surgery approaches 100%. Increasingly, the indications for thoracoscopy include therapeutic resections of pulmonary nodules in cases of limited lung metastases and bronchogenic carcinoma when pulmonary function is poor. Successful diagnostic and therapeutic resection by thoracoscopy requires intraoperative localization of the lesion within the collapsed lung. The indications and methods of thoracoscopic surgery and preoperative localization are discussed.

Biopsy, Needle↗
PubMed1995

Superior hypogastric plexus block for chronic pelvic pain in the presence of endometriosis: CT techniques and results.

PURPOSE: To evaluate the use of superior hypogastric plexus block with computed tomographic (CT) guidance in patients with endometriosis and chronic pelvic pain. MATERIALS AND METHODS: Seven blocks were performed on an outpatient basis in five women with endometriosis and pelvic pain. In the first four patients, one or two 20-gauge, 15-cm needles were placed anterior to the spine at the common iliac bifurcation from a posterior approach. In the fifth patient, the block was performed from an anterior approach with a single needle. RESULTS: One procedure resulted in mild pain relief, three in considerable pain relief, one in complete midline pain relief with no change in the lateral pain, and one in complete pain relief. One procedure was terminated because anesthetic was injected into the peritoneal cavity. There were no other complications. CONCLUSION: CT-guided superior hypogastric plexus block is easily performed and can be used to assess whether chronic pelvic pain can be attenuated by blocking the superior hypogastric plexus.

Adult↗
PubMed1995

The radiologic and pathologic spectrum of biliary hamartomas.

OBJECTIVE: The purpose of our study was to correlate the spectrum of radiologic and pathologic findings in a series of patients with biliary hamartomas and known extrahepatic malignancy. MATERIALS AND METHODS: Biliary hamartomas were diagnosed in 18 patients with a primary malignant lesion who had liver biopsy for evaluation of possible metastatic disease. Prebiopsy imaging studies included CT in 16 patients and sonography in 11. Imaging studies were reviewed retrospectively and correlated with findings at surgery and on pathologic examination. The hamartomas were classified histologically by the degree of cystic dilatation of bile ducts within the lesion. RESULTS: Radiologically, biliary hamartomas presented a spectrum of findings including one or two circumscribed lesions (5-10 mm in diameter) in four patients; multiple (about five) lesions (approximately 5 mm each) in one patient; innumerable tiny, nearly uniform (2-5 mm) lesions in two patients; and innumerable lesions of varying size (2-15 mm) in three patients. Among the patients with innumerable lesions, the nodules were either uniformly or nonuniformly distributed throughout the liver. In all cases, the lesions were hypodense on contrast-enhanced CT scans and hypoechoic on sonograms. In eight patients, the lesions were not visible by imaging but biopsies were done at surgery when single or multiple tiny nodules were noted on the liver surface. The diagnosis was made by either wedge or core-needle biopsy; fine-needle aspirations were nondiagnostic. Pathologic examination revealed single or multiple hamartomas of varying sizes ranging from solid to largely cystic lesions; the degree of cystic dilatation did not correlate with imaging findings. Visibility on imaging correlated with larger lesion size; small surface lesions were usually occult. CONCLUSION: Biliary hamartomas cause single or multiple nonspecific hepatic lesions that may mimic metastases. This diagnosis should be considered in patients with a primary malignant tumor when single or multiple small hepatic lesions are seen, regardless of uniformity of size or distribution.

Adult↗
PubMed1994

Tarsal coalition: depiction and characterization with CT and MR imaging.

PURPOSE: To compare computed tomography (CT) and magnetic resonance (MR) imaging in the detection, localization, and characterization of tarsal coalitions. MATERIALS AND METHODS: Preoperative CT and MR images were obtained for 10 feet in nine patients (eight male and one female patients), aged 11-18 years who were unresponsive to conservative therapy. Results from two blinded readers were compared with results from surgery. RESULTS: Five calcaneonavicular and four medial subtalar coalitions were found at surgery. One patient had synovitis. CT depicted six coalitions and four were characterized correctly, but the fibrous coalitions were not characterized correctly. MR depicted all coalitions and seven were characterized correctly, including the fibrous coalitions. At MR imaging, proliferative synovitis was incorrectly characterized as a fibrous coalition. CONCLUSION: These results suggest that MR imaging depicts all coalitions but may not be able to help differentiate synovitis from fibrous coalitions and that CT has limitations in the depiction of fibrous coalitions.

Adolescent↗
PubMed1994

Breast implants: incidental findings on CT.

The mammographic, sonographic, and MR appearances of both normal and abnormal breast implants have been described. Breast implants are occasionally seen on chest CT scans obtained for other reasons; however, we know of no published reports on the CT findings in a series of patients with breast implants. We present a retrospective review of CT findings in 18 patients with 27 breast implants that illustrates the spectrum of findings that can be seen in asymptomatic patients.

Breast↗
PubMed1994

CT done 4-6 hr after CT arterial portography: value in detecting hepatic tumors and differentiating from other hepatic perfusion defects.

OBJECTIVE: Nontumorous perfusion defects occur during CT arterial portography (CTAP) as normal variants or in cirrhosis, focal fatty infiltration, and portal vein obstruction. The purpose of this study was to determine whether delayed CT 4-6 hr after CTAP improves sensitivity to hepatic tumors and differentiates them from other hepatic perfusion defects. SUBJECTS AND METHODS: CTAP was done at 1-cm increments on 26 patients for evaluation of hepatic tumors. Delayed CT scans were obtained 4-6 hr later in all patients. Two observers retrospectively reviewed the CT scans obtained during CTAP and recorded size, shape, and location of suspected hepatic tumors. Confidence levels were assigned for each tumor. The delayed CT scan was then interpreted in conjunction with the CT scans obtained during CTAP, and confidence levels were reassigned. Surgical correlation was obtained for all patients. In the 26 patients, 86 masses were found at surgery. The sensitivity and number of false-positives for both CTAP alone and CTAP combined with delayed CT were compared with a two-tailed Student t-test. Receiver-operating-characteristic analysis also was performed. RESULTS: CTAP detected 73 (85%) of the 86 hepatic masses. Delayed CT had no effect on the sensitivity of CTAP. However, adding delayed CT decreased the total number of false-positives by 11, a statistically significant difference (p < .05). Receiver-operating-characteristic analysis revealed a significantly greater (p < .05) area under the curve (Az index) of 0.927 +/- 0.025 for CTAP combined with delayed CT compared with 0.886 +/- 0.032 for CTAP alone. Delayed CT was most useful for larger (> 1 cm) wedge-shaped perfusion defects and least useful for smaller (< 1 cm) round defects. CONCLUSION: Delayed CT has no effect in detecting tumors but may be useful for differentiating tumors from other hepatic perfusion defects seen on CTAP. The greatest benefit of delayed CT is in evaluating regions obscured by large wedge-shaped perfusion defects on CT scans obtained during CTAP.

Colorectal Neoplasms↗