Biomedical subjects

Udalrich Buell

Publications and source records attributed to Udalrich Buell.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Mechanisms of myocardial hypoperfusion during rotational atherectomy of de novo coronary artery lesions and stenosed coronary stents: insights from serial myocardial scintigraphy.

BACKGROUND: Rotational atherectomy (rotablation) frequently results in transient myocardial hypoperfusion due to peripheral vessel obstruction. This study compares the incidence, extent, and severity of perfusion defects induced by rotablation of de novo coronary lesions with rotablation of in-stent restenosis. METHODS AND RESULTS: Twenty-five patients undergoing rotablation for restenosed stents (group A) were studied by technetium 99m sestamibi single photon emission computed scintigraphy at rest before rotablation, during rotablation, and 2 days after the procedure. For semiquantitative analysis, perfusion in 24 left ventricular regions was expressed as percentage of maximal sestamibi uptake. The results were compared with those of 25 patients treated for de novo coronary lesions (group B). Transient perfusion defects were observed in 22 (88%) of 25 patients in group A and, similarly, in 23 (92%) of 25 in group B. Perfusion was significantly reduced during rotablation in 3.1 +/- 2.6 (mean +/- SD) regions in group A and in 3.3 +/- 2.5 regions in group B. Perfusion in the region with maximal reduction during rotablation in groups A and B was 77% +/- 13% and 76% +/- 15% at baseline. Technetium uptake decreased to 59% +/- 19% and 54% +/- 14% during rotablation (P <.001 vs baseline, P = not significant for A vs B) and returned to 76% +/- 16% and 76% +/- 15% after rotablation. Intravascular ultrasonography indicated no correlation between the volume of ablated plaque and the extent and severity of perfusion defects in in-stent restenosis. CONCLUSIONS: Incidence, extent, and severity of rotablation-related transient hypoperfusion are influenced by neither the type nor the quantity of ablated plaque material. Thus embolization of ablated plaque may be less important compared with other factors such as microcavitation or platelet aggregation.

Atherectomy, Coronary↗

PubMedDate not supplied

Assessment of myocardial viability in dysfunctional myocardium by resting myocardial blood flow determined with oxygen 15 water PET.

BACKGROUND: There is controversy about the role of decreased resting blood flow as the pathophysiologic correlate of hibernating myocardium. The aim of this study was an absolute quantification of volumetric myocardial blood flow (MBFvol) in dysfunctional myocardium with different viability conditions as defined by fluorine 18 deoxyglucose (FDG) positron emission tomography (PET) while taking into consideration the functional recovery after revascularization. The impact of MBFvol in the diagnosis of functional recovery was also investigated. METHODS AND RESULTS: Forty-two patients with severe coronary artery disease and dysfunctional myocardium underwent resting oxygen 15 water PET, as well as FDG PET and technetium 99m tetrofosmin single photon emission computed tomography, all attenuation-corrected. Relative FDG and Tc-99m tetrofosmin uptake (normalized to the segment with 100% Tc-99m tetrofosmin uptake), as well as MBFvol (myocardial blood flow multiplied by the water-perfusable tissue fraction to account for the flow to the entire segment volume), were determined in 18 myocardial segments per patient. Viability in dysfunctional segments (estimated by ventriculography) with reduced Tc-99m tetrofosmin uptake of 70% or lower was classified as viable (FDG >70%, mismatch) or nonviable (FDG < or =70%, match). Fifteen patients underwent revascularization and were followed up. Mismatch segments with improved function were classified as hibernating myocardium. Mean MBFvol in viable myocardium was slightly reduced (0.60 +/- 0.02 mL x min(-1) x mL(-1)) compared with that in normokinetic myocardium (0.64 +/- 0.01 mL x min(-1) x mL(-1)) (P = .036) and was significantly higher than in nonviable myocardium (0.36 +/- 0.01 mL x min(-1) x mL(-1)) (P < .001). Receiver operating characteristic analysis confirmed an FDG uptake greater than 70% as the optimal threshold to predict functional recovery (diagnostic accuracy [ACC], 76%). MBFvol in hibernating myocardium (0.62 +/- 0.04 mL x min(-1) x mL(-1)) was not significantly reduced compared with that in normokinetic myocardium (0.66 +/- 0.02 mL x min(-1) x mL(-1)) and was significantly higher than in persistently dysfunctional myocardium (0.51 +/- 0.04 mL x min(-1) x mL(-1)) (P < .05). The ACC of MBFvol greater than 0.40 mL x min(-1) x mL(-1) as the threshold to predict functional recovery was 61% but did not improve the accuracy of FDG PET by itself. CONCLUSIONS: In patients with severe coronary artery disease and dysfunctional myocardium, MBFvol as determined with O-15 water differs significantly between viable and nonviable myocardium as determined by FDG PET and is not significantly reduced in hibernating compared with normokinetic myocardium. Therefore chronically reduced resting blood flow appears unlikely to be the pathophysiologic correlate of the functional state of hibernation. However, MBFvol does not improve the ACC of FDG PET by itself.

Adult↗

PubMedDate not supplied

The value of positron emission tomography in the follow-up for breast cancer.

BACKGROUND: The aim of this study was to investigate the diagnostic value of FDG PET in the follow-up for breast cancer in disease-free patients and patients suspected of having recurrent or metastatic disease. As a single imaging tool, PET can be compared with the conventional diagnostic means used for different examination sites. PATIENTS AND METHODS: A total of 73 PET studies were carried out on 57 patients who had been diagnosed as having breast cancer. Sixteen patients had two PET scans. Thirty-eight scans (52.%) were performed in a follow-up setting. Thirty-five PET scans were performed in patients suspected of having recurrent disease or elevated tumor marker. Depending on the region of suspicion, conventional imaging included computed tomography, magnetic resonance imaging, chest X-ray, ultrasound and X-ray. All the patients in our study were followed-up for a period of 12 months. RESULTS: PET correctly identified metastatic or recurrent disease in 25 out 27 cases of clinical suspicion. In patients examined because of elevated tumour marker CA 15-3, PET was able to detect recurrence or metastatic disease in six of the eight patients. The absence of disease was correctly diagnosed by PET in 35 out of 38 scans in 24 patients in the follow-up for breast cancer. The overall sensitivity and specificity for PET was 80.6% and 97.6%, respectively. On the basis of a yearly rate of disease progression of 5-8%, the mean positive predictive value was 74.5% and the mean negative predictive value 98.3%. CONCLUSION: PET has been shown to have impact on the staging and management of recurrent or metastatic breast cancer in cases of suspicion and in a follow-up setting. The current oncological situation can be clarified with a single basic imaging modality.

Abdominal Neoplasms↗