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Biomedical subjects

T L Krebs

Publications and source records attributed to T L Krebs.

At least 19 recordsLinked to original sources
PubMed2000

Imaging features of posttransplantation lymphoproliferative disorder in pancreas transplant recipients.

OBJECTIVE: The purpose of this study was to describe the imaging features of posttransplant lymphoproliferative disorder (PTLD) in pancreas transplant recipients. CONCLUSION: The prominent image finding of PTLD in pancreas transplant recipients is diffuse allograft enlargement, an appearance that may be indistinguishable from the image findings of acute pancreatitis or transplant rejection. However, failure of response to immunosuppressive therapy, presence of intraallograft or extraallograft focal masses, or organomegaly may suggest the diagnosis of PTLD.

Adult↗
PubMed2000

Liver and bone window settings for soft-copy interpretation of chest and abdominal CT.

OBJECTIVE: We evaluated whether the use of multiple window and level settings on a soft-copy workstation improves diagnostic accuracy on chest and abdominal CT. We hypothesized that routinely using window and level settings during soft-copy interpretation would beneficially affect the final diagnosis without compromising efficiency. MATERIALS AND METHODS: Two hundred three randomly selected abdominal and chest CT scans were interpreted by three radiologists using a four-monitor soft-copy workstation (images per screen, nine; resolution, 2K). After the initial interpretations, all scans were reevaluated by the same radiologists using additional liver and bone window and level settings. Differences in conspicuity and characterization of abnormalities were graded on a three-point scale. RESULTS: Conspicuity and characterization of abnormalities were improved in 67% of abnormal findings (81/121; p = 0.01). Improvement (a finding that substantially affected the final diagnosis) was present in 18% of abnormal findings (22/121; p = 0.04). On average, the evaluation of images at multiple window and level settings required an additional 40 sec per case. CONCLUSION: The use of multiple window and level settings during soft-copy interpretation resulted in improved lesion detectability and characterization with greater diagnostic efficacy. Using soft-copy workstations, radiologists can evaluate images using multiple settings without compromising efficiency.

Bone Diseases↗
PubMed2000

MR imaging of the thoracoabdominal junction.

Recent advances in MR imaging techniques and its multiplanar capability allow for improved detection and characterization of benign and malignant processes occurring in the thoracoabdominal region. It is important to the staging process of patients with known malignancy to correctly diagnose incidental masses in this region, including hepatic or adrenal lesions, which initially may be identified by other imaging modalities. MR imaging provides a complimentary role in lesion detection and diagnosis that may ultimately affect therapeutic management and outcome.

Abdomen↗
PubMed1999

MammoWeb continuing medical education (CME): a web-based breast imaging CME program.

The ubiquity of the world-wide web allows unique educational opportunities for continuing medical education (CME). We have designed a comprehensive breast imaging CME curriculum to permit individual physicians in their homes or offices to use personal computers to ease the burden of this process. Category 1 CME credits can be earned off-hours without having the physician travel out of town. In addition, since the course is computer-based, the overall costs to the participant are substantially reduced. The program can be updated on an ongoing basis to include new technology or to provide additional information requested by the users.

Breast Diseases↗
PubMed1999

Acute pancreatic transplant rejection: evaluation with dynamic contrast-enhanced MR imaging compared with histopathologic analysis.

PURPOSE: To evaluate the use of dynamic contrast material-enhanced gradient-recalled-echo MR imaging for the diagnosis of acute pancreatic transplant rejection, as confirmed at histopathologic analysis. MATERIALS AND METHODS: Thirty MR imaging studies were performed in 25 patients within 3 days of percutaneous biopsy or pancreatectomy. The mean percentage of parenchymal enhancement (MPPE) at dynamic contrast-enhanced MR imaging was calculated. RESULTS: Biopsy findings were no evidence of rejection (n = 7 [23%]), mild rejection (n = 10 [33%]), moderate (n = 6 [20%]) and severe (n = 2 [7%]) acute rejection, and infarction (n = 5 [17%]). The corresponding MPPEs at 1 minute were 106%, 66%, 62%, 57%, and 3%, respectively. Overlap of cases in the normal and rejection groups occurred; however, using an MPPE cutoff of 100% resulted in a sensitivity of 96%. An MPPE over 120% was seen in the normal group only. The MPPE was significantly greater in the normal group than in the rejection or infarction group (P < .05). CONCLUSION: Dynamic contrast-enhanced MR imaging is highly sensitive for the detection of acute pancreatic transplant rejection. Because of overlap of cases in the normal and rejection groups, percutaneous biopsy may be needed in some cases. Pancreatic allografts with infarction can be clearly identified.

Acute Disease↗
PubMed1999

Percutaneous abdominal and pelvic interventional procedures using CT fluoroscopy guidance.

OBJECTIVE: The purpose of our study was to assess the use of low-milliamperage CT fluoroscopy guidance for percutaneous abdominopelvic biopsy and therapeutic procedures. MATERIALS AND METHODS: We reviewed the clinical records and relevant imaging studies of 97 patients who underwent 119 percutaneous CT fluoroscopy-guided abdominal or pelvic procedures: fluid collection aspiration or drainage catheter insertion (n = 59), biopsy (n = 49), hepatocellular carcinoma ethanol ablation (n = 6), chemoneurolysis (n = 4), and brachytherapy catheter insertion (n = 1). These procedures were guided using a helical CT scanner providing real-time fluoroscopy reconstruction at six frames per second. A control panel and video monitor beside the gantry allowed direct operator control during all interventional procedures. RESULTS: One hundred twelve (94.1%) procedures were successfully performed using either a stand-off needle holder and continuous real-time CT fluoroscopy guidance or incremental manual insertion and intermittent CT fluoroscopy to confirm position. Image quality using low milliamperage was adequate for needle or drainage tube placement in all but two low-contrast liver lesions. Two hematomas were accessed but yielded no fluid on aspiration; one drainage procedure was abandoned after the patient developed endotoxic shock. Imaging of ethanol distribution during injection facilitated tumor ablation and neurolytic procedures. CT fluoroscopy allowed rapid assessment of needle, guidewire, dilator, and catheter placement, especially in nonaxial planes. Average CT fluoroscopy time for biopsy and therapeutic procedures was 133 sec (range, 35-336 sec) and 186 sec (range, 20-660 sec), respectively. CONCLUSION: CT fluoroscopy is a practical clinical tool that facilitates effective performance of percutaneous abdominal and pelvic interventional procedures.

Abdomen↗
PubMed1998

Creating a digital video-based teaching file for interventional procedures using CT fluoroscopy.

A computerized radiology education teaching file application, MRW (Multimedia Radiology Workstation), was produced in our department as a collaboration of faculty, fellows and a doctoral student. This inexpensive and flexible system is novice-programmable and is capable of capturing images from multiple modalities (including still and cine image) and organizing them into individual electronic teaching cases. Help and tutorial functions support the main case display functions.

Computer-Assisted Instruction↗
PubMed1998

Frequency of abdominal CT findings in AIDS patients with M. avium complex bacteraemia.

BACKGROUND: Use of blood culture studies for early diagnosis of Mycobacterium avium complex (MAC) infection has become important due to the recent development of effective antibiotic therapy for this condition. This study assessed the abdominal computed tomography (CT) findings in patients with AIDS who presented with bacteraemic MAC infection. METHODS: A retrospective analysis of abdominal CT scans was performed in 24 patients who presented with MAC-positive blood culture. CT images were reviewed specifically to evaluate for lymph node enlargement and attenuation, hepatomegaly, splenomegaly, bowel wall abnormality and for any other pathological changes. Comparison was made to prior reports of the CT findings in this disease process. RESULT: Enlarged intra-abdominal mesenteric and/or retroperitoneal lymph nodes were found in 10 patients (42%). These nodes were characterized by homogeneous, soft-tissue attenuation in eight of the 10 patients. Hepatomegaly, splenomegaly and small bowel wall thickening were noted in 12 (50%), 11 (46%) and four (14%) patients, respectively. CT findings were evaluated as normal in six (25%) patients. CONCLUSIONS: Enlarged mesenteric and/or retroperitoneal lymph nodes in AIDS patients with bacteraemic MAC were observed much less frequently on CT than previously reported in AIDS patient populations. Normal abdominal CT findings do not exclude this diagnosis and may reflect a trend towards earlier detection of MAC disease.

AIDS-Related Opportunistic Infections↗
PubMed1998

Clinical pathway for enhanced parent and preterm infant interaction through parent education.

The article discusses the importance of implementing a clinical pathway in the neonatal intensive care unit that emphasizes parent education. Through an extensive literature review, a clinical path was developed that incorporates parent education through an individualized, developmentally supportive model of interaction. The clinical path is designed to be utilized as a teaching tool from birth to discharge from the hospital. The path can serve as a guide for teaching and identifying learning objectives a long a time line as well as for providing consistent documentation.

Adult↗
PubMed1998

Evaluation of biopsy needles and prototypic needle guide devices for percutaneous biopsy with CT fluoroscopic guidance in simulated organ tissue.

The authors evaluated accuracy and success rates for placement of fine-aspiration, core, and coaxial biopsy needles in pork meat with three needle guide devices and computed tomographic fluoroscopic guidance. Accuracy and reliability with a metallic sponge-forceps needle holder was equal to or greater than those with other devices, and it was preferred by operators due to its lighter weight and single-handed manipulation. All needle holders functioned poorly with thin-walled needles.

Animals↗
PubMed1998

Torsion of intraperitoneal renal transplants: imaging appearances.

OBJECTIVE: Torsion of a renal transplant is a rare complication with nonspecific clinical manifestations. Prompt detection is necessary to allow surgical treatment and to preserve renal function. We describe the radiologic appearances of torsion of intraperitoneal renal transplants in patients who have undergone simultaneous renal and pancreatic transplantation or dual renal transplantation. CONCLUSION: Renal transplant torsion should be suspected when a change in renal axis associated with abnormal perfusion occurs in an intraperitoneal kidney.

Adult↗
PubMed1997

Cytoablative therapy with combined resection and cryosurgery for limited bilobar hepatic colorectal metastases.

BACKGROUND: Cryosurgery can be employed in patients with unresectable hepatic metastases when the tumor size and the number of metastases are limited. However, local recurrence can result from incomplete ablation. We proposed a trial of complete cytoablation with a combined approach of cryosurgery and hepatic resection for patients with bilobar hepatic metastases. METHODS: Seven patients underwent cryosurgery alone (CRYO). Seven additional patients underwent combined resection and cryosurgery (CRYO+RES) for bilobar metastases. RESULTS: In the CRYO group, 5 of 7 patients had at least one centrally located tumor. All 5 of these patients had early recurrence at the site of ablation. In the CRYO+RES group complete ablation was achieved in 7 of 7. Two (28.6%) of these patients developed local recurrence. CONCLUSION: Cytoablation of hepatic metastases can be safely achieved with combined hepatic resection and cryosurgery in selected patients. Long-term survival data are necessary before advocating widespread application of this approach.

Aged↗
PubMed1997

End stage renal transplant failure: allograft appearances on CT.

INTRODUCTION: Failed renal allografts often are left in situ in patients who revert to chronic dialysis therapy or who undergo retransplantation. These patients may be investigated with computed tomography (CT) imaging for allograft-related or other abdominopelvic disease. This study describes the appearances of failed renal transplants on CT. METHODS: A retrospective study was made of the clinical records and CT findings on 25 studies in 14 patients, 5-156 months (average, 44 months) following allograft failure. CT studies were reviewed for allograft position, size, shape, attenuation value, calcification, cyst formation, related abdominopelvic findings and the presence of other allografts. Correlation was made with clinical findings in all patients and with pathological findings in six. RESULTS: Global shrinkage was noted in eight failed allografts, all of which were asymptomatic. Enlargement of two failed allografts was due to symptomatic acute infarction of the allograft in one patient and subacute haemorrhagic infarction simulating a tumour mass in another. CT attenuation values in individual allografts varied markedly due to fatty replacement, hydronephrosis, haemorrhage or dense calcification. Both a failed longstanding and a functioning more recently placed renal allograft were present in seven patients, four of whom had acute complications related to the more recently transplanted kidney. Two of six calcified allografts were mistaken for opacified bowel on CT. CONCLUSION: A wide spectrum in size, shape and attenuation values may be detected in failed renal allografts by CT. These organs may be the site of acute disease despite their lack of physiological function or may be diagnostically confusing findings in patients with acute disease related to more recently transplanted organs.

Adult↗
PubMed1997

Evaluation of 14- and 11-gauge directional, vacuum-assisted biopsy probes and 14-gauge biopsy guns in a breast parenchymal model.

PURPOSE: To compare commercially available 14-guage core biopsy guns and 11- and 14-gauge, directional, vaccum-assisted biopsy probes for tissue yield and fragmentation. MATERIALS AND METHODS: One hundred passes were made through fresh turkey breasts by using each of 11 14-gauge, automated biopsy gun-needle combinations and a directional, stereotactic, vacuum-assisted biopsy system equipped with 11- or 14-gauge probes. Specimens were measured for total weight, individual length, diameter, and number of fragments. RESULTS: Among the handheld devices, the Pro-Mag 2.2 gun (Manan Medical Products, Northbrook, Ill) and 14-gauge Biopsy-Cut needle (Bard, Covington, Ga) had the greatest yield (17.7 mg per core specimen); this combination also produced the greatest percentage of nonfragmented cores (83%). Directional, vacuum-assisted biopsy specimens were significantly larger (P < .001): 36.8 mg per core specimen for the 14-gauge probe and 94.4 mg per core specimen for the 11-gauge probe. Specimens obtained with directional, vacuum-assisted biopsy were more fragmented than those obtained with spring-actuated, two-stage, long-throw, automated biopsy systems. CONCLUSION: Statistically significant differences with various biopsy devices are seen in the breast tissue yield and in fragmentation.

Adult↗
PubMed1997

MR imaging evaluation with a transrectal surface coil of local recurrence of prostatic cancer in men who have undergone radical prostatectomy.

OBJECTIVE: The objective of this study was to evaluate the ability of transrectal surface coil MR imaging to reveal local recurrence of malignancy in men who have had radical prostatectomy for prostatic adenocarcinoma. SUBJECTS AND METHODS: We performed prospective analysis of 41 men who had undergone radical prostatectomy (range of time since surgery, 8 months to 5 years; mean, 26 months), 35 of whom had clinical suspicion of recurrent prostatic cancer and the remaining six of whom had no clinical evidence of recurrent prostatic cancer (controls). Our imaging used a transrectal surface coil on a 1.5-T MR scanner. Sagittal and axial fat-saturated T2-weighted fast spin-echo as well as axial T1-weighted unenhanced and gadolinium-enhanced MR images of the prostatic bed were acquired in all patients. Thirty-one of the 35 men with clinical suspicion of recurrent prostatic cancer had elevated prostate-specific antigen (PSA) levels (> or = 0.4 ng/ml), and 22 of these 31 men had a palpable prostatic bed module or induration. The four of 35 men with clinical suspicion of recurrent prostatic cancer who had PSA levels less than 0.4 ng/ml had a palpable prostatic bed nodule or induration. Transrectal biopsy of the prostatic bed was directed by digital palpation or transrectal sonography in all 35 men with clinical suspicion of recurrent malignancy. RESULTS: Thirty-one of the 35 men who had clinical suspicion of local recurrence of prostatic cancer had a soft-tissue nodule revealed in the prostatic bed by transrectal surface coil MR imaging. Compared with the adjacent muscle, all nodules were isointense on the T1-weighted images, hyperintense on the T2-weighted images, and enhanced with gadolinium administration. The 22 patients who had an abnormal MR scan and a palpable nodule or induration and the nine patients with elevated PSA levels, no palpable abnormality, and an abnormality revealed by MR imaging underwent transrectal biopsy; all had recurrent prostatic cancer proven by histology in the four patients with a palpable prostatic bed nodule or induration and normal PSA levels, MR imaging showed no distinct soft-tissue nodule or area of enhancement in the prostatic bed; transrectal biopsy of the palpable nodule or induration yielded fibrosis but no malignancy in all four patients. In the six control patients with no clinical evidence of local recurrence, MR imaging revealed no evidence of recurrent malignancy; all six control patients continue to have no clinical evidence of recurrent prostatic cancer with a minimum follow-up of 22 months. Thus, the sensitivity of MR imaging in revealing local recurrence of prostatic cancer was 100% (95% confidence interval = 89-100%), and the specificity also was 100% (95% confidence interval = 69-100%). The kappa coefficient was 1.0 (p < .001). CONCLUSION: MR imaging with a transrectal surface coil is a useful imaging tool to evaluate men who have undergone radical prostatectomy and are suspected of having local recurrence of malignancy in the prostatic bed.

Adenocarcinoma↗
PubMed1997

The adrenal gland: radiologic-pathologic correlation.

The adrenal glands are affected by complex physiologic and neoplastic processes. Recently described computed tomography densitometry and chemical shift MR imaging techniques are useful to distinguish between benign and malignant masses. Knowledge of the basic gross pathologic and histologic correlates of adrenal disease helps in applying these new imaging methods and in understanding established cross-sectional studies.

Adrenal Gland Diseases↗
PubMed1996

Large-core biopsy guns: comparison for yield of breast tissue.

PURPOSE: To compare seven large-core, long-throw, 14-gauge biopsy guns for yield and quality of breast tissue obtained. MATERIALS AND METHODS: A two-phase, randomized and blinded study was performed. In the first phase, four fully automated 14-gauge biopsy guns (BIP, Manan, Biopsy, and ASAP) and one semiautomated device (Temno) were used to obtain breast cores from a cadaver. Samples were assessed for volume, number of fragments, and crush artifact. In the second phase, seven biopsy guns (previously mentioned guns plus Monopty and Ultra-Cut guns) were used to obtain cores from a breast parenchyma model. These cores were then evaluated for weight, volume, and number of fragments. RESULTS: The mean specimen volume of cadaveric breast tissue obtained was 17.9 mm3 for the BIP gun, 17.8 for the Manan gun, 14.9 for the Biopsy gun, 14.1 for the ASAP gun, and 9.9 for the Temno gun. The Temno gun obtained statistically significantly smaller volumes than all other guns. For the breast parenchyma model, mean obtained volumes were 24.5, 24.1, 16.2, 21.7, 17.5, 20.0, and 15.2 mm3, respectively. The BIP and Manan guns yielded statistically significantly larger cores than all other guns except the ASAP. CONCLUSION: Yields of breast tissue provided by each biopsy device differed statistically significantly. BIP and Manan biopsy guns yielded the greatest volume of core tissue, which may facilitate histopathologic diagnosis from breast biopsies performed with imaging guidance.

Animals↗