Biomedical subjects
Publications and source records attributed to P Croisille.
To date, most applications of cardiovascular MRI relate to the evaluation of major vessels. We review the currently established indications for thoracic vascular MRI and will touch on the advances that are likely to change the way we examine great thoracic vessels.
BACKGROUND: Contrast-enhanced fast magnetic resonance (MR) images of acute, reperfused human infarcts demonstrate regions of hypoenhancement and hyperenhancement. The relations between the spatial extent and time course of these enhancement patterns to myocardial risk, infarct, and no-reflow regions have not been well characterized. METHODS AND RESULTS: The proximal left anterior descending coronary artery was occluded in 11 closed-chest dogs for 90 minutes followed by 2 days of reperfusion. Regional blood flow was determined by use of radioactive microspheres. The animals were studied at the 2-day time point with contrast-enhanced fast MRI (Signa 1.5 T, General Electric). Thioflavin-S was administered to demarcate no-reflow regions. The hearts were then excised, sectioned into five base-to-apex slices, stained with 2,3,5-triphenyltetrazolium chloride (TTC), and photographed under room light (for TTC) and ultraviolet light (for thioflavin). The spatial extents of thioflavin-negative, TTC-negative, and risk regions were compared planimetrically with MRI hypoenhanced and hyperenhanced regions. The spatial locations of subendocardial hypoenhancement in MR images correlated closely with those of thioflavin-negative regions. Microsphere blood flow in these regions was significantly reduced compared with remote regions (0.37 +/- 0.09 versus 0.88 +/- 0.10 mL/min per gram, respectively, P < .001) and with baseline (0.37 +/- 0.09 versus 0.87 +/- 0.15 mL/min per gram, P < .01). The spatial extent of hyperenhancement was smaller than the risk region (r = .64, slope = 0.48, P < .001) but highly correlated with TTC-negative regions and were, on average, 12% larger (r = .93, slope = 1.12, P = .035). CONCLUSIONS: In contrast-enhanced MR images of 2-day-old reperfused canine infarcts, myocardial regions of hypoenhancement are related to the no-reflow phenomenon. Approximately 90% of the myocardium within hyperenhanced regions is nonviable.
PURPOSE: To determine whether extraction of pulmonary vessels from computed tomographic (CT) images with automated segmentation improves the detection of pulmonary nodules. MATERIALS AND METHODS: Simulated nodules were superimposed on normal spiral CT images. Eight patients referred for CT assessment of pulmonary nodules were selected for clinical evaluation. Vessels were extracted from both the simulation and clinical study with a three dimensional seeded region-growing algorithm. Three experienced radiologists were asked to locate the nodules and assign a level of confidence to their findings. Sensitivity and proportion of false-positive results per case (FPC) were calculated. Observer performance was evaluated by alternate free-response receiver operating characteristic analysis. RESULTS: Extraction of vascular structures from CT scans improved sensitivity from 63% to 84% in the simulation study and from 58% to 78% in the clinical study. The proportion of FPC decreased from 52% to 24% and from 55% to 12%, respectively. Radiologists performed consistently better with the segmented images than with the original images in both the simulation (P = .006) and the clinical (P = .0013) study. CONCLUSION: Automated vessel subtraction and extraction improves detection of pulmonary nodules.
We present a case of left striatocapsular infarction manifest clinically as a transient right hemiparesis. MRI showed a left striatocapsular infarct. Striatocapsular infarction, unlike lacunar infarction, is often associated with occlusive disease of the carotid artery. In order to screen the carotid vessels, cervical MR angiography (MRA) was performed during the same examination, demonstrating a left internal carotid artery occlusion, confirmed by contrast arteriography. MRA, a noninvasive modality, can be a useful adjunct to MRI, when diagnostic information concerning the cervical carotid artery is needed.
This paper describes an automated edge detection method for the delineation of the endo- and epicardial borders of the left ventricle from magnetic resonance (MR) images. The feasibility of this technique was demonstrated by processing temporal series of cardiac MR images obtained in 12 healthy subjects and acquired from the apex to the base of the heart in multiple anatomic short axis planes with a breath-hold cine-MR acquisition sequence. This procedure allows the entire heart to be imaged in less than 5 min. The automatic program correctly identified the edges in most cases. In poor contrasted images, a fast and user-friendly interactive procedure was used to correct the border delineation. The proposed method for the contour tracing requires a limited degree of control by the user and thus considerably reduces the tedious and long operator time inherent in the usual manual contour tracing tool. The left ventricular volumes were directly measured from these sets of contours by using the Simpson rule, allowing the end-diastolic volumes (EDV), the end-systolic volumes (ESV), the ejection fraction (EF) and the myocardial mass to be determined. The values measured in this study with the dedicated software were similar to the literature values (EDV = 78.3 ml/m2; ESV = 21.1 ml/m2; EF = 73%). Associated with the ultrafast breath-hold cine-MR imaging, the described edge detection method provides an efficient clinical tool for the direct assessment of cardiac function.
PURPOSE: Primary cerebral lymphoma is a rare disease. The aim of this study is to compare the survival of the patients treated with radiotherapy alone vs. patients treated with a combined schedule of radio-chemotherapy. Our results will be compared with currently published data and main prognostic factors will be briefly discussed. PATIENTS AND METHODS: Between 1974 and 1990, 27 cases of primary cerebral lymphoma were diagnosed at our institution. All patients had biopsy-proven disease, the pathology of which was reviewed for this study. RESULTS: The overall median survival time was 24 months and one-, two- and three-year overall survival was 59, 46 and 29% respectively. The median radiation dose was 46 Gy, ranging from 19.5 to 60 Gy. The median dose per fraction was 2 Gy (ranging from 1.61 to 3 Gy). The median elapsed treatment time was 32 days (ranging from three to 45 days). We were not able to demonstrate any statistically significant difference between patients who received radiotherapy alone (n = 14, median survival time = 24 months) and those who received a combination of chemotherapy and radiotherapy (n = 11, median survival time = 30 months), (p = 0.4). Prognostic factors of survival were tested using a univariate analysis (Wilcoxon test). Parameters such as mass appearance (unilobular, p = 0.048), performance status at the time of the diagnosis (0 to 1, p = 0.014), and CT imaging (hypodense, p = 0.043) influenced positively survival. Centroblastic histology (Kiel) was found associated with a negative prognosis (p = 0.043). CONCLUSION: In our experience, there is no statistically significant difference of survival between patients treated with radiotherapy alone or with a combined treatment of radio-chemotherapy. Other prognostic factors of survival were discovered, although the analysis was univariate, due to the limited number of patients. Multicentric prospective studies should be elaborated in order to optimize the treatment of this disease.
The article presents a case of subacute coronary artery thrombosis investigated by classic methods, coronary angiography, and MRI. T1- and T2-weighted images showed high signal intensity within the lumen of the right coronary artery corresponding to the methemoglobin content of the thrombus. Dynamic sequence images with intravenous gadolinium contrast agent displayed lack of right coronary artery enhancement, confirming coronary occlusion. The coronarography revealed the same finding. MRI appears to be a promising method of coronary thrombosis assessment.
Several studies have served to underline the interest of MRI in the diagnosis and assessment of epidural abscess and malignant extradural spinal tumors. In our work, one of the quantitatively greatest published to this day, 64 patients presenting epidural pathology were evaluated by means of MRI. All the explorations were brought about through weighted multiplaned sequences T1, T2 and gadolinium injection. The pathological spectrum encountered is comprised of: metastatic extradural spinal tumors (58%), primary extradural spinal tumors (7%), epidural localizations of hematological diseases (9%), epidural abscess (25%), and one case of epidural hematoma. Assessment was brought to bear upon behavior in relation to type of sequence, spread of disease, medullary effects, type of enhancement following gadolinium injection. Degree of correlation with clinical data and surgical findings was also appraised. As concerns tumourous epidural pathology, positive diagnosis due to a lesion hinges upon the T1 and T2 sequences. Gadolinium's contribution is restricted to analysis of perivertebral and vertebral spreading; it also facilitates recognition of the spinal cord in circumferential epiduritis. So much said, gadolinium appears to be essential in frequently less compressive forms of infectious epiduritis; it plays a pronounced role in both follow-up of their evolution and recognition of acute epidural hematoma.