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D A Bluemke

Publications and source records attributed to D A Bluemke.

At least 19 recordsLinked to original sources
PubMed1999

Switchable multicoil array for MR micro-imaging of breast lesions.

High-resolution breast imaging may improve differentiation between benign and malignant lesions and may be important for refining treatment strategy. This article presents a new, flexible design of a breast-imaging coil capable of providing breast images of a high level of spatial resolution. Referred to as a switchable coil array, the design uses small-diameter surface coils that provide high sensitivity of detection, which, combined with a relatively small field of view, affords a high degree of spatial resolution (up to 200 microm). Remote selection of the coil pair closest to the position of the lesion in the breast permits coverage of the whole breast without changing the position of the coils or the patient. High-resolution MR images of phantom and volunteer patients with benign and malignant breast lesions are presented.

Biopsy, Needle↗
PubMed1999

Primary sclerosing cholangitis: MR imaging findings with pathologic correlation.

OBJECTIVE: The purpose of this study was to evaluate MR imaging findings of primary sclerosing cholangitis, to compare them with histopathologic findings, and to determine if these findings help differentiate primary sclerosing cholangitis from other disorders that result in end-stage liver disease. MATERIALS AND METHODS: MR imaging was performed in 40 patients (27 men, 13 women; age range, 13-72 years; mean, 47 years) with primary sclerosing cholangitis over a 9-year period. In 16 patients who underwent orthotopic hepatic transplantation and in seven patients who underwent needle biopsy, correlation was made between MR imaging and pathologic findings. RESULTS: Focal signal changes in the liver parenchyma were seen on T2-weighted images as peripheral wedge-shaped zones of increased signal intensity in 29 patients (72%), as a reticular pattern in 15 patients (38%), and as periportal edema in 16 patients (40%). Lobar atrophy involved the right lobe in three patients (8%) and the left lobe in 11 patients (28%); hypertrophy of the caudate lobe was seen in nine patients (23%). Features of portal hypertension were seen in 14 patients (35%). Histologic assessment showed zones of segmental atrophy and scarring on the periphery of the liver. CONCLUSION: Peripheral wedge-shaped areas of high T2 signal intensity and dilatation of bile ducts are characteristic MR features of primary sclerosing cholangitis. Pathologic correlation suggests that these features may be related to underlying perfusion changes and bile duct inflammation in patients with primary sclerosing cholangitis.

Adolescent↗
PubMed1999

New MR imaging contrast agents.

Many new MR contrast agents are undergoing laboratory development, are in clinical trials, or are being used for routine clinical applications. These agents function by targeting specific receptors that allow the agent to accumulate within the reticuloendothelial system, the hepatobiliary system, or the blood pool. Each agent has unique properties that offer advantages over unenhanced and gadolinium chelate-enhanced MR imaging. Use of these agents, however, requires an understanding of their current and potential clinical indications and inherent limitations. This article reviews the development, evaluation, and clinical application of a number of these agents, including ferumoxides, Mn-DPDP, AMI-227, SHU-555A, Gd-EOB/DTPA, Gd-BOPTA, and MS-325.

Biliary Tract↗
PubMed1999

Cardiac disease in the adult: MR evaluation.

Cardiac MR imaging to date has provided detailed information regarding cardiac structure and anatomy. Recent developments in imaging speed have broadened the applications of cardiac MR from the research laboratory to a wide variety of clinical applications involving assessment of both cardiac function and perfusion. In this review, we present methods used for MR evaluation of acquired cardiac disease in the adult. Applications to ischemic heart disease, cardiomyopathy, coronary imaging, myocardial perfusion, and pericardial disease are discussed.

Adult↗
PubMed1998

Quantification and time course of microvascular obstruction by contrast-enhanced echocardiography and magnetic resonance imaging following acute myocardial infarction and reperfusion.

OBJECTIVES: We aimed to validate contrast-enhanced echocardiography (CE) in the quantification of microvascular obstruction (MO) against magnetic resonance imaging (MRI) and the histopathologic standards of radioactive microspheres and thioflavin-S staining. We also determined the time course of MO at days 2 and 9 after infarction and reperfusion. BACKGROUND: Postinfarction MO occurs because prolonged ischemia produces microvessel occlusion at the infarct core, preventing adequate reperfusion. Microvascular obstruction expands up to 48 h after reperfusion; the time course beyond 2 days is unknown. Though used to study MO, CE has not been compared with MRI and thioflavin-S, which yield precise visual maps of MO. METHODS: Ten closed-chest dogs underwent 90-min coronary artery occlusion and reperfusion. Both CE and MRI were performed at 2 and 9 days after reperfusion. The MO regions by both methods were quantified as percent left ventricular (% LV) mass. Radioactive microspheres were injected for blood flow determination. Postmortem, the myocardium was stained with thioflavin-S and 2,3,5-triphenyltetrazolium chloride. RESULTS: Expressed as % total LV, MO by MRI matched in size MO by microspheres using a flow threshold of <40% remote (4.96+/-3.52% vs. 5.32+/-3.98%, p=NS). For matched LV cross sections, MO by CE matched in size MO by microspheres using a flow threshold of <60% remote (13.27+/-4.31% vs. 13.5+/-4.94%, p=NS). Both noninvasive techniques correlated well with microspheres (MRI vs. CE, r=0.87 vs. 0.74; p=NS). Microvascular obstruction by CE corresponded spatially to MRI-hypoenhanced regions and thioflavin-negative regions. For matched LV slices at 9 days after reperfusion, MO measured 12.94+/-4.51% by CE, 7.11+/-3.68% by MRI and 9.18+/-4.32% by thioflavin-S. Compared to thioflavin-S, both noninvasive techniques correlated well (CE vs. MRI, r=0.79 vs. 0.91; p=NS). Microvascular obstruction size was unchanged at 2 and 9 days (CE: 13.23+/-4.11% vs. 12.69+/-4.97%; MRI: 5.53+/-4.94% vs. 4.68+/-3.44%; p=NS for both). CONCLUSIONS: Both CE and MRI can quantify MO. Both correlate well with the histopathologic standards. While MRI can detect regions of MO with blood flow <40% of remote, the threshold for MO by CE is <60% remote. The extent of MO is unchanged at 2 and 9 days after reperfusion.

Animals↗
PubMed1998

Magnitude and time course of microvascular obstruction and tissue injury after acute myocardial infarction.

BACKGROUND: Microvascular obstruction within an area of myocardial infarction indicates worse functional recovery and a higher risk of postinfarction complications. After prolonged coronary occlusion, contrast-enhanced MRI identifies myocardial infarction as a hyperenhanced region containing a hypoenhanced core. Because the time course of microvascular obstruction after infarction/reperfusion is unknown, we examined whether microvascular obstruction reaches its full extent shortly after reperfusion or shows significant progression over the following 2 days. METHODS AND RESULTS: Seven dogs underwent 90-minute balloon occlusion of the left anterior descending coronary artery (LAD) followed by reflow. Gadolinium-DTPA-enhanced MRI performed at 2, 6, and 48 hours after reperfusion was compared with radioactive microsphere blood flow (MBF) measurements and myocardial staining to define microvascular obstruction (thioflavin S) and infarct size (triphenyltetrazolium chloride, TTC). The MRI hypoenhanced region increased 3-fold during 48 hours after reperfusion (3.2+/-1.8%, 6.7+/-4.4%, and 9.9+/-3.2% of left ventricular mass at 2, 6, and 48 hours, respectively, P<0.03) and correlated well with microvascular obstruction (MBF <50% of remote region, r=0.99 and thioflavin S, r=0.93). MRI hyperenhancement also increased (21.7+/-4.0%, 24.3+/-4.6%, and 28.8+/-5.1% at 2, 6, and 48 hours, P<0.006) and correlated well with infarct size by TTC (r=0.92). The microvascular obstruction/infarct size ratio increased from 13.0+/-4.8% to 22.6+/-8.9% and to 30.4+/-4.2% over 48 hours (P=0.024). CONCLUSION: The extent of microvascular obstruction and the infarct size increase significantly over the first 48 hours after myocardial infarction. These results are consistent with progressive microvascular and myocardial injury well beyond coronary occlusion and reflow.

Analysis of Variance↗
PubMed1998

Gadolinium-enhanced three-dimensional MR angiography of the entire aorta and iliac arteries with dynamic manual table translation.

Spoiled fast three-dimensional gradient-echo magnetic resonance imaging of the aorta and iliac arteries was performed in 13 patients after administration of a single bolus of gadopentetate dimeglumine. The imaging table was moved manually 40-45 cm between two acquisitions. Arterial signal-to-noise ratio did not vary significantly between the thoracic (aortic) and pelvic stations, but venous signal-to-noise ratios increased and arterial contrast-to-noise ratios decreased on the pelvic studies. This method was feasible and increased anatomic coverage.

Adult↗
PubMed1998

CT and MR evaluation of pancreatic cancer.

CT scanning has a greater than 90% accuracy in staging patients with pancreatic cancer. New, powerful imaging techniques, such as spiral CT and gadolinium-enhanced MRI, can evaluate subtle changes in pancreatic contours and overall vascularity of the gland to further increase staging reliability. Spiral CT in particular provides excellent depiction of small vessels, high levels of pancreatic enhancement, and lack of respiratory misregistration. High resolution contrast-enhanced MR techniques may provide a new role for MR imaging in the evaluation of pancreatic cancer. This article discusses state-of-the-art CT and MR imaging techniques for pancreatic evaluation.

Diagnosis, Differential↗
PubMed1997

Observer variation in the detection of acetabular bone deficiencies.

To determine observer variation in the detection of acetabular bone deficiencies, 42 pairs of frontal (AP) and lateral hip radiographs and CT studies for total hip arthroplasty patients obtained within an average of 4 weeks of each other were reviewed separately by five radiologists and one orthopedic surgeon. Interobserver variations were calculated for each individual reading the films using kappa values. The individual film readings were then compared with a consensus reading of the CT data. When separate observers were analyzed, agreement on plain film readings was slight to fair (av. kappa = 0.1440 +/- 0.1047). The individual observers were not able to give readings which were very consistent with the CT consensus reading, resulting in a low sensitivity (65%) and specificity (74%) for acetabular defect classification with plain radiographs. The identification of acetabular bone defects from the AP and lateral views of the hip is highly subjective and variable from observer to observer.

Acetabulum↗
PubMed1997

Thrombosis of the deep femoral vein: a potential pitfall of color flow duplex Doppler ultrasonography.

This case illustrates a potential pitfall of color flow duplex Doppler ultrasonography with compression in the evaluation of suspected deep venous thrombosis (DVT). Because of its low cost, accuracy, and noninvasiveness, ultrasonography is the appropriate first choice in the evaluation of suspected DVT, but there does exist the possibility of a false-negative examination. Magnetic resonance venography (MRV) should be reserved for cases in which there is a high clinical suspicion for DVT, as well as either morbid obesity that would limit the evaluation of deep pelvic and deep femoral veins or conflicting results of other imaging studies. All cases of suspected thrombosis, including those not adequately evaluated by ultrasonography, can be accurately assessed by MRV, which is not as invasive as standard venography.

Adult↗
PubMed1997

Benign and malignant musculoskeletal masses: MR imaging differentiation with rim-to-center differential enhancement ratios.

PURPOSE: To assess the diagnostic potential of the rim-to-center differential enhancement ratio in the magnetic resonance (MR) imaging differentiation of benign from malignant musculoskeletal masses. MATERIALS AND METHODS: Dynamic gadolinium-enhanced fast multiplanar spoiled gradient-recalled acquisition in the steady state imaging was performed to evaluate 17 one and soft-tissue masses (10 malignant, seven benign) in 14 patients. The rim-to-center differential enhancement ratio was determined from images at the maximal enhancement rate. The difference in differential enhancement ratios between benign and malignant masses was evaluated and compared with the maximum rate of enhancement for each mass. RESULTS: Nine of 10 malignant masses showed rapid rim enhancement with delayed central fill-in. This enhancement pattern was absent in benign masses. The average rim-to-center differential enhancement ratio was 0.64 +/- 0.26 for malignant masses and -0.16 +/- 0.33 for benign masses (P < .001). This difference was statistically significant. The average maximum rate of enhancement was 3.41%/sec +/- 2.20 for malignant masses and 2.74%/sec +/- 2.46 for benign masses (P > .05). CONCLUSION: Intratumoral enhancement patterns of malignant and benign masses differ because of differences in vascular architecture. These preliminary results suggest that the rim-to-center differential enhancement ratio has potential as an additional parameter for the MR imaging differentiation of indeterminate musculoskeletal masses.

Adolescent↗
PubMed1997

Thoracoabdominal aorta in Marfan syndrome: MR imaging findings of progression of vasculopathy after surgical repair.

PURPOSE: To determine the natural history of vasculopathy of the thoracoabdominal aorta in patients with Marfan syndrome after composite graft repair of the aortic root. MATERIALS AND METHODS: A total 224 magnetic resonance (MR) images obtained in 48 patients with Marfan syndrome over a period of 2.3-9.4 years (mean, 5.0 years) were retrospectively reviewed. On each image, the diameter of the thoracoabdominal aorta was measured and the presence of dissection or major peripheral artery aneurysms was determined. RESULTS: In 31 (65%) of the 48 patients, no statistically significant change (3 mm or less increase in diameter) in the diameter of the aorta occurred during the study (group 1); in the remaining 17 (35%) patients, a significant change occurred (greater than 3 mm increase) (group 2). The mean initial diameter of the native aorta was slightly larger in group 2 (mean, 27 mm +/- 8 [standard deviation]) than in group 1 (mean, 23 mm +/- 6). In group 1, the mean rate of dilation was 0.07 mm/y +/- 0.2; in group 2, the rate was 2.3 mm/y +/- 3.3. Two patients with aortic dissection were in group 1, whereas 14 such patients were in group 2 (P < .001). Aneurysms that involved major peripheral arteries were present in four (13%) of the 31 group 1 patients and in 12 (71%) of the 17 group 2 patients (P < .001). Surgical intervention was necessary in two group 1 patients and in 14 group 2 patients (P < .001). CONCLUSION: A subset of patients with Marfan syndrome manifested multiple forms of vasculopathy, including progressive aortic dilation, dissection, and peripheral artery aneurysm after composite aortic graft repair of the ascending aorta. Patients with these characteristics merit more frequent MR follow-up since further surgery was often necessary in these individuals.

Adolescent↗
PubMed1997

Extremity veins: evaluation with fast-spin-echo MR venography.

The authors evaluated a flow-independent magnetic resonance (MR) imaging technique in extremity veins with slow flow that relies on the prolonged T2 of blood to create angiographic contrast. A commercially available heavily T2-weighted fast-spin-echo sequence was optimized for MR venography in volunteer and phantom studies. Good depiction of venous anatomy was routinely obtained with the optimized method. Fast-spin-echo MR venography allowed evaluation of slow-flow systems such as the calf and forearm veins.

Adult↗