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Biomedical subjects

J R Crass

Publications and source records attributed to J R Crass.

At least 19 recordsLinked to original sources
PubMed1992

Traumatic lacerations of the aorta and great vessels with a normal mediastinum at radiography.

The possibility of a "normal" mediastinum at conventional chest radiography in a patient with a lacerated aorta or great vessel from blunt thoracic trauma has not been evaluated objectively. All 1991 members of the Society of Thoracic Radiology were sent a questionnaire asking for examples of such cases. A similar questionnaire was placed in the newsletter of the Society of Cardiovascular and Interventional Radiology. The literature also was reviewed for cases. Seventy-eight of 327 questionnaires were returned with responses. Eight responders reported 12 examples of a normal mediastinum radiograph in a patient with a lacerated aorta. Review of the same radiographs by the authors yielded three normal and nine subtly abnormal mediastina. One additional normal radiograph was obtained of a patient with a lacerated great vessel. Another 16 cases of lacerated aortae (n = 12) and great vessels (n = 4) in patients with normal mediastina were found through a literature search; images from three of these were reviewed by the authors. Although this is an infrequent event, the mediastinum can be normal at plain chest radiography with traumatic lacerations of the aorta and great vessels.

Humans↗
PubMed1992

CT evidence for the "osseous pinch" mechanism of traumatic aortic injury.

OBJECTIVE: Our prior experiments suggested that traumatic laceration of the aorta induced by rapid deceleration results from pinching of the aorta between the spine and the anterior bony complex (manubrium, clavicle, and first rib). This study examines that hypothesis with in vivo CT data. MATERIALS AND METHODS: In 22 patients with angiographically and surgically proved lacerations of the proximal descending aorta, chest CT scans were obtained before (18) or after (four) surgical repair. The point of impact of the anterior bony complex with the anterior surface of the thoracic spine during compression of the thorax was predicted by simulated rotation of the first rib based on calculations made from the CT scans. RESULTS: In all 22 patients, the projected site of impact of the anterior bony complex with the spine corresponded to the actual injured aortic segment as determined with angiography. CONCLUSION: Our data further support the proposed "osseous pinch" mechanism of injury to explain traumatic tears of the aorta.

Aorta, Thoracic↗
PubMed1992

Radiological application of three-dimensional imaging systems.

Three-dimensional displays are becoming more frequent in medical imaging. As PACS and imaging workstations as nodes on networks provide greater ease and availability of three-dimensional reconstructions of digital data applications are increasing. Applications at this time are limited to high-contrast structures. In CT these are complex fractures or deformities. Three-dimensional display clarifies the anatomy and facilitates operative planning. In MRI, MR angiography is the principal application. The ability to rotate the data set in three dimensions eliminates potential overlap, increasing the sensitivity and specificity of the technique. Three-dimensional imaging is becoming available for scintigraphic and sonographic studies but applications have not yet been clarified.

Data Display↗
PubMed1991

Improvement in CT pelvimetry.

When computed tomographic (CT) digital radiography is used for pelvimetry, measurement error may occur. Geometric distortion in the lateral direction of the CT digital radiograph can lead to an error in any measurement of the transverse pelvic inlet. The authors measured the magnitude of this error on two scanners and present a general method for correction of this potential error. The authors also showed that an additional dose reduction is possible if the patient is imaged in the posteroanterior rather than anteroposterior projection.

Female↗
PubMed1990

A proposed new mechanism of traumatic aortic rupture: the osseous pinch.

The currently accepted mechanism to explain traumatic aortic rupture from rapid deceleration involves a combination of traction, torsion, and hydrostatic forces. The authors hypothesize that aortic isthmus lacerations result from a pinch of the aorta between the spine and the anterior bony thorax (manubrium, clavicle, and first ribs) during chest compression caused by abrupt deceleration. Compression of an articulated, normally moving thoracic skeleton containing a synthetic aorta consistently caused transection of the aorta at the isthmus between the spine and anterior bony structures. Analysis of rotation of the first rib in 10 consecutive patients undergoing computed tomography of the chest demonstrated interposition of the distal aortic arch and isthmus between the vertebrae and anterior bony thorax in each instance. Aortas excised from laboratory dogs were pinched between structures simulating bones to reproduce intimal and medial lesions indistinguishable from lesions associated with naturally occurring traumatic disruptions. Although further studies in cadaveric specimens are necessary to confirm this mechanism of injury, the authors believe that their results support the osseous-pinch mechanism of aortic rupture.

Animals↗
PubMed1989

Clinical efficacy of Kitecko ultrasonic conductor.

A homogeneous synthetic polymer block (Kitecko) was evaluated for ultrasound imaging of small parts, superficial structures, and the pediatric patient. The block is intended to be used as an offset and replaces the traditional way of scanning with water paths, fluid-filled surgical gloves or IV bags. A randomized paired comparison of the Kitecko pad conductor and a water path system (IV bag) was performed. One hundred pediatric and adult patients were scanned using both conductors. The images were encoded and subsequently evaluated for image quality, including artifact, attenuation, resolution, and distortion. A statistical analysis showed significantly higher scores (P less than .01) with the Kitecko substance when compared to water path scanning when evaluating for reverberation artifact, scatter artifact, and spatial resolution.

Humans↗
PubMed1989

Correlation of Fourier spectral shift-determined hepatic acoustic attenuation coefficients with liver biopsy findings.

We calculated hepatic acoustic attenuation coefficients (ACs) in 13 patients who had liver biopsies and in 3 normal subjects by means of Fourier spectral analysis of reflected ultrasound signals from increasing depths in the liver. The ACs were correlated with estimated percentage area occupied by fat in the liver biopsies; linear regression analysis revealed a correlation coefficient of r = .78 (p less than .001). The presence of fibrosis did not correlate with AC.

Biopsy, Needle↗
PubMed1989

Technetium-99m sulfur colloid spleen imaging following partial pancreatectomy and splenic artery and vein resection.

We retrospectively studied the records and [99mTc]sulfur colloid (TSC) spleen studies of 38 patients who underwent distal pancreatectomy with splenic artery and vein resection for donation to HLA-compatible relatives. The spleens in immediate postoperative TSC studies were normal in 11% of cases, showed no uptake in 16%, showed diffusely decreased uptake in 50%, and showed focal defects in 26%. Twenty of the patients, all with abnormal initial TSC studies, had repeat studies 2 wk to 3 yr later; 15% showed no change, 35% showed some improvement, and 45% became normal. One of six patients with no TSC uptake required splenectomy 2 days after pancreatectomy for splenic infarction. These data suggest that the spleen usually survives splenic artery and vein resection. Absent splenic TSC uptake raises the possibility of splenic infarction.

Adult↗
PubMed1988

Ultrasonography of rotator cuff tears: a review of 500 diagnostic studies.

Ultrasonography of the rotator cuff has been shown to be of value in diagnosing rotator cuff tears. This report summarizes our experience with our first 500 diagnostic examinations. All patients were examined in the hyperextended internal rotation view with commercially available high-resolution real-time ultrasound equipment. Patients were diagnosed as having a rotator cuff tear if a focal echogenic lesion or a defect within the rotator cuff was identified. This study confirmed the value of ultrasonography for the diagnosis of rotator cuff tears. Accuracy, sensitivity, and specificity all exceeded 90%, and correlated with surgical findings. This was better than arthrography in the same patient population. Ultrasound is an accurate noninvasive method of examining the rotator cuff for the presence of tears. We suggest that rotator cuff ultrasonography is the procedure of choice for the diagnosis of tears if adequate instrumentation is available.

Arthrography↗
PubMed1988

Upper abdomen: CT findings following partial hepatectomy.

The appearance on computed tomographic (CT) scans of the upper abdomen after partial hepatectomy is complex. The findings expected at CT should not be confused with those of surgical complications, such as abscess, biloma, or hematoma. The findings on CT scans and the records of 17 patients who had undergone partial hepatectomy for malignancy were reviewed. Operations included wedge resection, left medial and lateral segmentectomies, left lobectomy, right subsegmentectomy, right lobectomy, and extended right lobectomy (trisegmentectomy). When partial hepatectomy had been performed with no complications, findings at CT included a small region of low attenuation at the surgical margin, probably due to transient accumulation of blood and bile; a right pleural effusion; extraluminal gas; shift of abdominal organs; hepatic regeneration; and fat attenuation at the resection margin representing the omental patch placed at surgery. Findings associated with surgical complications--such as abscess, biloma, and hematoma--included large or high-attenuation perihepatic and subphrenic fluid collections that did not conform to the resection margin.

Adolescent↗
PubMed1988

Tendon echogenicity: ex vivo study.

Recent publications discussing the echogenicity of normal tendon have described it variously as hyperechoic or hypoechoic. Since the echogenicity of tendon has been used to define normality and abnormality, certain knowledge of the normal echogenicity of tendon is crucial. Fresh tendon and muscle from beef hock was scanned with sector- and linear-array-transducer imaging at multiple angles and distances. The echogenicity of tendon was found to be very angle-dependent, a characteristic known as anisotropy. Scanned perpendicular to its long axis with a linear-array transducer, tendon was significantly more echogenic than muscle. With a change in angle, echogenicity of tendon decreased relative to that of muscle (the echogenicity of muscle remained the same), becoming isoechoic at angles of 2 degrees -7 degrees and hypoechoic at greater angles. Tendon studied with a sector transducer exhibited varying echogenicity. If echogenicity is used as a diagnostic criterion, the angle of the interrogating ultrasound beam must be very specifically defined.

Humans↗
PubMed1988

Percutaneous aspiration and drainage of abdominal fluid collections after pancreatic transplantation.

Pancreatic transplantation, performed to avert or delay the long-term complications of insulin-dependent diabetes mellitus, is sometimes complicated by the development of intraabdominal fluid collections. We performed 33 sonographically guided and CT-guided percutaneous abdominal aspiration and drainage procedures in 22 transplant patients; 25 procedures were done with the pancreatic graft-in-situ, and eight were done after removal of the transplant. All 11 percutaneous aspirations performed in 10 patients were successful in obtaining microbiologic culture material, and there were no complications. Sixteen percutaneous catheter drainages were performed in 13 patients with the graft-in-situ. Subsequent surgical intervention was avoided after only five (31%) of these drainage procedures. However, further intervention was unnecessary after five (83%) of six percutaneous catheter drainages in five patients who had previously undergone transplant pancreatectomy. No significant short-term or long-term complications were identified. Guided percutaneous aspiration of abdominal fluid collections after pancreatic transplantation is a safe and effective means of obtaining diagnostic material, and guided catheter drainage is definitive treatment in approximately one-third of procedures with the graft-in-situ and in most procedures done after removal of the graft.

Adult↗
PubMed1988

Current concepts in the radiographic evaluation of the rotator cuff.

This review discusses the disease of the rotator cuff and evaluates our current tools for imaging it. The rotator cuff consists of the cojoined tendons of the short rotator muscles of the shoulder. Derangements of the cuff, which can result from degeneration, trauma, or overuse, are frequent causes of shoulder pain. Until the present decade, imaging of the cuff depended on injection of contrast into either the underlying joint (arthrogram) or overlying bursa (bursogram). Computed tomography (CT) has added additional dimensions to arthrography but has not played a major role in the diagnosis of cuff pathology. Ultrasonography (US) has been shown to be of diagnostic value in imaging cuff tears and has shown promise in defining pathology in the intact cuff. Magnetic resonance imaging (MRI) has the potential for imaging the cuff; its roles here are not yet defined.

Humans↗