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H Bosmans

Publications and source records attributed to H Bosmans.

At least 55 records · Page 3Linked to original sources
PubMed1999

Three-dimensional MR angiography in the evaluation of thoracic outlet syndrome.

OBJECTIVE: The objective is to present our initial experience with the combination of three-dimensional time-resolved contrast-enhanced MR angiography and T1-weighted spin-echo imaging for investigation of vascular compression related to thoracic outlet syndrome. CONCLUSION: In patients with clinical signs of thoracic outlet syndrome suggesting vascular elongation or compression, this technique proves to be robust, and its results are comparable to those of conventional catheter angiography. Our results allow precise identification of the anatomic structure(s) responsible for the clinical symptoms and show the effect of arm hyperabduction on the patency of the subclavian vessels.

Adult↗
PubMed1999

Confrontation of mammography systems in flanders with the European Guidelines for Quality Assurance in mammography screening. Analysis of initial results.

From May 1997 to April 98, 30 radiological centers made an agreement with the Leuvens Universitair Centrum voor Kankerpreventie (LUCK) for the work out of physical and technical quality control in mammography screening. A protocol was used based on the European Guidelines for Quality Assurance. The reports of all 30 acceptance tests were retrospectively reviewed. The following parts showed to be most critical: alignment of radiation field and film in the bucky, tube voltage precision, automatic exposure controller, average optical density of a standard exposure, dark room and its safe lights. The mean film gradient was in the majority of the centers higher than what is prescribed in the European document. This is acceptable and even desirable whenever daily quality control shows that the development system is sufficiently stable. Although it is difficult to compare the scores for the specific tests with results in other countries, there is evidence that the tendencies are very similar.

Absorptiometry, Photon↗
PubMed1998

Fast FLAIR MRI in childhood white-matter abnormalities.

We compared a fast fluid-attenuated inversion recovery (FLAIR) pulse sequence with a dual-echo short tau fast inversion-recovery (DESTTIR) sequence in 20 children with white matter abnormalities. Although the overall image quality of DESTTIR images was better, the lesion-to-background contrast was significantly higher with the fast FLAIR pulse sequence and lesion detection was more accurate.

Adolescent↗
PubMed1998

T2-weighted MR imaging of the uterus: comparison of optimized fast spin-echo and HASTE sequences with conventional fast spin-echo sequences.

OBJECTIVE: Our objective was to compare the value of a half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence with optimized fast spin-echo and conventional fast spin-echo techniques in evaluation of the uterus. SUBJECTS AND METHODS: Optimized fast spin-echo imaging was compared with fast spin-echo and HASTE imaging, for both image quality and ability to assess the zonal anatomy of the uterus, in 40 volunteers. In optimized fast spin-echo imaging, the imaging time was reduced using partial-Fourier reconstruction, reducing the echo spacing, and increasing the echo train length. RESULTS: HASTE imaging offered the least motion artifact of all techniques. On optimized fast spin-echo imaging, motion artifacts were moderate to severe in 10% of patients. On fast spin-echo imaging, motion artifacts were moderate to severe in 40% of patients. Optimized fast spin-echo imaging was superior to the other two techniques in terms of anatomic sharpness and overall image quality. CONCLUSION: Although HASTE imaging offers the unique feature of providing images free of motion artifacts, optimized fast spin-echo imaging appears to be the preferred technique for T2-weighted imaging of the uterus.

Adolescent↗
PubMed1997

Preliminary experience with a new double-echo half-Fourier single-shot turbo spin echo acquisition in the characterization of liver lesions.

A new double-echo half-Fourier single-shot turbo spin echo technique has been implemented in which two images are obtained per excitation pulse, one with an echo time (TE) of 60 ms and another with a TE of 438 ms. The acquisition window per image is 380 ms and is determined by the echo spacing of 4.3 ms and the echo train length of 88 for images with resolution of 160 x 256. No breath holding was performed. The aim of the study was to test whether the additional information of the late TE image improves the characterization of liver lesions. Twenty-eight patients with 39 focal liver lesions (9 cysts, 11 hemangiomas, and 19 solid lesions) were imaged with the new technique, and signal intensity (SI) ratios of lesion and liver were obtained. A t-test analysis showed that in the TE 60 ms image, SI ratios of cysts and hemangiomas were not significantly different, whereas in the TE 438 ms images the two types of lesions can be classified. Signal intensity ratios of solid lesions were in both images clearly lower than those of cysts and hemangiomas. The technique, therefore, seems a promising and straightforward new tool for the characterization of liver lesions.

Cysts↗
PubMed1997

Follow-up of aortic dissection: contribution of MR angiography for evaluation of the abdominal aorta and its branches.

Spin-echo MR is an established method to evaluate thoracic aortic dissections, but is not well suited to study the abdominal aorta. In this study we evaluated whether MR angiography could provide a complete examination of the abdominal aorta. In 28 patients (40 MR studies) with suspected (n = 6) or known (n = 34) aortic dissection, MR studies were performed. Thoracic aorta was evaluated with spin-echo and gradient-recalled-echo MR imaging. Axial two-dimensional time-of-flight MR angiography with thin overlapping slices was used to study the abdominal aorta. Intermediate and high signal intensity on MR angiography was interpreted as patent flow, and low signal was interpreted as thrombus. The presence of an intima flap and the re-entry site could be depicted in all MR studies. Thrombus in the false channel was seen in 8 studies. The origin of the abdominal visceral branches and their relation to the false-true channel could be depicted, except in 4 of 80 renal arteries studied. Extension of the dissection into the coeliac trunk was seen in 2 and in the superior mesenteric artery in 10 studies. Dilatation of the suprarenal abdominal aorta was seen in 20 studies, and of the infrarenal aorta in 9 studies. MR angiography provides valuable information about the abdominal aorta and its branches in patients with aortic dissection. This makes MR imaging appealing as the preferred imaging modality for the diagnosis and follow-up of aortic dissection.

Aortic Dissection↗
PubMed1997

Localization and determination of infarct size by Gd-Mesoporphyrin enhanced MRI in dogs.

BACKGROUND: Accurate localization and sizing of a myocardial infarction are necessary for clinical decision making and even more in research. Gd-Mesoporphyrin enhanced magnetic resonance imaging (MRI) was recently shown to specifically delineate necrosis in liver tumors, renal and muscle necrosis and myocardial infarction in rats. In this study, we investigated this technique's potential to accurately delineate myocardial infarction in a larger animal species, the dog. METHODS: Myocardial infarction was induced in 8 dogs by ligation of the left anterior descending coronary artery, 4 of which were reperfused after 3 hr Gd-Mesoporphyrin (0.05 mmol/kg) was injected intravenously 210 min after the onset of ischemia (n = 6) or after 24 hr in 2 dogs with non-reperfused infarctions. MRI was performed 10 hr after administration of Gd-Mesoporphyrin. In vivo MRI consisted of EKG-triggered, respiratory gated T1-weighted spin echo and segmented turboFLASH long and short axis measurements. Post-mortem, a spin echo short axis measurement was repeated. Infarct size was determined planimetrically by TTC staining of left ventricular slices. RESULTS: In all instances, there was a very close qualitative agreement between the MRI and TTC defined myocardial infarction. Quantitatively, the linear regression from post-mortem MRI to TTC determined infarct size yielded a result very close to the line of identity (regression coefficient: 0.980 +/- 0.026, p < 0.000001, adjusted R2 = 0.964). CONCLUSION: We conclude that Gd-Mesoporphyrin enhanced MRI is a promising tool for the accurate delineation of myocardial infarction.

Animals↗
PubMed1997

Comparison of manganese biodistribution and MR contrast enhancement in rats after intravenous injection of MnDPDP and MnCl2.

PURPOSE: To compare the time course of the MR enhancing properties and biodistribution of manganese (Mn) in rats given i.v. Mn dipyridoxyl diphosphate (MnDPDP) or Mn chloride (MnCl2). MATERIAL AND METHODS: Twenty-four adult rats were injected i.v. with 5 mumol/kg MnDPDP or MnCl2, or with 0.5 ml/kg saline. High resolution T1-weighted MR imaging was performed during early (10 min), mid (2 h) and late (24 h) phases after injection. Mn concentrations in major organs were measured by using an ICP-AES technique, and correlated with MR findings. RESULTS: Variable degrees of signal enhancement of major organs observed in MR images corresponded with the amount of Mn uptake after injection of MnDPDP or MnCl2. A prominently lower cardiac, pancreatic and hepatic uptake of Mn was seen at 10 min in rats injected with MnDPDP compared with those given MnCl2 and this was reflected in a difference in signal intensity (SI) in the MR images. At 2 h, the Mn content and SI in the major organs were similar with both MnDPDP and MnCl2. An overall Mn clearance was achieved at 24 h without any important organ retention, with kidney excretion of Mn seen only with MnDPDP. CONCLUSION: With both MnDPDP and MnCl2, the Mn uptake correlates with the SI enhancement in tissues. The reduced initial cardiac uptake of Mn after MnDPDP treatment compared to MnCl2 may account for the favourable cardiovascular safety of the contrast agent. These data contribute to an understanding of SI enhancement by MnDPDP, and are consistent with other studies showing that at a dose of 5 mumol/kg, MnDPDP can be safely used as a potent MR organ-specific contrast agent.

Animals↗
PubMed1997

Magnetic resonance imaging-histomorphologic correlation studies on paramagnetic metalloporphyrins in rat models of necrosis.

RATIONALE AND OBJECTIVES: The authors intended to confirm previous findings that paramagnetic porphyrins are avid only for intratumoral nonviable tissues, but not for viable tumor cells, and to test the hypothesis that necrosis, regardless of location and origin, can be visualized by metalloporphyrin enhanced magnetic resonance imaging (MRI). METHODS: Intravenous administrations of gadolinium mesoporphyrin (Gd-MP), manganese tetraphenylporphyrin (Mn-TPP), manganese methylpyrroporphyrin-gadopentetate dimeglumine complex (Mn-MPP-Gd) and manganese tetra(4-sulfonatophenyl)porphyrin (MnTPPS4) at 0.05 mmol/kg were compared with those of gadopentetate dimeglumine (Gd-DTPA) at 0.1 mmol/kg in 38 rats with cholestatic liver necrosis, alcohol- and laser-induced coagulation necrosis in liver, and skeletal muscle, reperfused hepatic infarction, and segmental renal infarction. T1-weighted spin echo MRI (TR/TE = 300/15 mseconds) was acquired before and as long as 48 hours after injection, matched with histologic findings, and correlated with Gd/ Mn tissue content measurements. RESULTS: Both Gd-DTPA and the four metalloporphyrins initially caused a similar nonspecific negative contrast enhancement in the necrosis. However, a strong and persisting positive enhancement (necrosis-to-normal contrast ratio ranging from 1.5 to 2.0) developed only with metalloporphyrins in all types of necrosis. In liver and kidney, Gd and Mn concentrations at 24 hours were comparable in necrotic and normal tissues. In muscle, the concentrations were more than eight times higher in necrotic than in normal tissue. CONCLUSIONS: The implied affinity of metalloporphyrins for necrosis with presumably increased relaxivity suggests a possible mode of targetability for MRI contrast media that may elicit novel applications.

Animals↗
PubMed1997

Imaging of gallbladder and biliary tract before laparoscopic cholecystectomy: comparison of intravenous cholangiography and the combined use of HASTE and single-shot RARE MR imaging.

To compare intravenous cholangiography (i.v.c.) and magnetic resonance imaging (MRI) as preoperative imaging techniques in patients scheduled for laparoscopic cholecystectomy. Twenty patients underwent i.v.c. and MRI, 40 axial 'localizer' images were first obtained with a half-Fourier single-shot turbo spin echo (HASTE) sequence. Next, an extremely high T2-weighted rapid acquisition relaxation enhancement (RARE) acquisition (TE = 1100 msec) was used for MR cholangiography. All images obtained with i.v.c. and MRI were independently analyzed by two observers. The relative visibility of the (normal or abnormal) gallbladder (GB), cystic duct (CD), and bile ducts (BD) on both types of images was scored as follows: 1 = MRI better than i.v.c.; 2 = no difference; 3 = i.v.c. better than MRI. We observed 3 anatomic variants: 1 of the cystic duct and 2 of the intrahepatic bile ducts; 15 patients had gallstones; one had cholecystitis. Magnetic resonance images were considered more informative than i.v.c.-images for visualization of GB in 11 patients (55%), for CD in 9 patients (45%), and in 8 patients (40%) for visualization of the CBD. Intravenous cholangiography outperformed MRI in the evaluation of the CBD and CD in one patient (5%). The combined use of half-Fourier single-shot RARE and high T2-weighted RARE MR imaging is a valuable alternative to i.v.c. in the preoperative evaluation of gallbladder and biliary tract.

Adult↗
PubMed1996

Paramagnetic metalloporphyrins: infarct avid contrast agents for diagnosis of acute myocardial infarction by MRI.

In previous experiments in tumors we demonstrated that metalloporphyrins are particularly avid for nonviable tumor components. This study was performed to find out whether these agents can be used as MRI contrast agents for the visualization of acute myocardial infarction (MI). A total of 44 rats, 6 normal controls and 38 with occlusive MI (2-24 h old), were used. Gadolinium mesoporphyrin (Gd-MP) or manganese tetraphenylporphyrin (Mn-TPP) was intravenously injected at doses of 0.1, 0.05, and 0.01 mmol/kg. Three to 24 h after injection, axial and coronal T1-weighted (TR/TE 300/15 ms) spin-echo MR images were obtained before and after killing the animals and correlated with triphenyl tetrazolium chloride (TTC) histochemical preparations. The Gd-MP content in infarcted and noninfarcted myocardium was measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). MRI without contrast media could not discern the MI. However, 3-24 h after injection of either Gd-MP or Mn-TPP, the infarcted area was positively stained on MR images. This area matched well with the negatively TTC-stained area on the heart slices (r = 0.97). The contrast ratios between the infarcted necrotic myocardium and the noninfarcted regions varied from 150 to 300% depending on the type of agents and doses used. Neither false-positive nor false-negative findings were encountered. The metalloporphyrin concentration was more than 10 times higher in the infarcted than in the noninfarcted heart. Metalloporphyrins appear to be promising MRI contrast agents for detection and quantification of necrosis in MI. These preclinical results may open new perspectives in cardiac imaging.

Animals↗
PubMed1996

Left ventricular radial tagging acquisition using gradient-recalled-echo techniques: sequence optimization.

Myocardial tagging with magnetic resonance (MR) imaging offers unique possibilities for noninvasive left ventricular (LV) strain analysis. True three-dimensional strain analysis can be achieved with tags implemented in cardiac short axis and long axis images. Spin-echo (SE) techniques have been used for these studies. However, this approach is time-consuming: images at different phases of the cardiac cycle have to be obtained in successive measurements and hence the total number of measurements equals the number of time frames. Moreover, the images are often degraded by flow and motion artifacts. The purpose of this study was to optimize a faster and more robust MR tagging sequence for use on a clinical whole-body 1 T MR system with optimal persistence of the tags during the entire cardiac cycle. The tagging pulses were implemented in gradient-recalled-echo (GRE) sequences and compared to SE-based acquisitions. The effects of the use of flow-compensating gradients, the excitation angles, and the angles of the saturation pulses have been studied with MR signal simulations and in comparative measurements in volunteers. GRE acquisitions with flow-compensating gradients are robust techniques for myocardial tagging acquisitions. Use of optimized flip angles and saturation pulses can significantly improve delineation of the tag and can be used up to at least 700 ms after the R-wave. Therefore, LV tagging with GRE acquisitions using optimized MR parameters is a robust and promising technique.

Heart↗
PubMed1996

Spiral CT of intracranial aneurysms: correlation with digital subtraction and magnetic resonance angiography.

Spiral CT and magnetic resonance angiography (MRA) were performed in ten patients with 14 intracranial aneurysms known from conventional angiography. All lesions, the smallest 3 mm in diameter, were visible on spiral CT and MRA. The neck of the aneurysm and its anatomical relations could very accurately be determined in all cases. Advantages of spiral CT over MRA are: a short acquisition time with reduction of motion artefacts, no dependence on flow rate or cardiac output, and excellent visualisation of calcification, thrombus and bony landmarks. Disadvantages are the necessity for iodinated contrast medium, long postprocessing and reconstruction time and the possibility of overlap of bone and venous blood.

Aged↗
PubMed1996

Contrast-enhanced MR angiography.

Despite many optimizations, the current limitations of plain MR angiography include: saturation that impairs the visualization of veins and arteries with slow flow and spin-dephasing signal voids in locations with turbulent flow. Recently, the use of contrast agents has been proposed to cope with these remaining problems. Because of induced shortening of the T1 of the blood, saturation in the blood vessels is overcome. As a result, arteries and veins are visualized with the same signal intensity, which makes the technique less flow-dependent. In combination with short T1-weighted acquisitions, today CE MRA can be obtained while the patient is holding his breath. This last approach is most promising for abdominal applications since the respiratory motion can be frozen. As these acquisitions also use very short echo times, spin dephasing can be reduced. In conclusion, the use of contrast agents has greatly increased the clinical usefulness of MR angiography.

Animals↗
PubMed1996

Magnetic resonance imaging of experimental tracheal transplantation.

RATIONALE AND OBJECTIVES: We evaluated the feasibility of using contrast-enhanced magnetic resonance (MR) imaging for in vivo monitoring of tracheal transplants in rabbits. METHODS: Plain and gadolinium-enhanced, high-resolution MR images were obtained from six rabbits 4 weeks to 6 months after an orthotopic tracheal transplantation (after heterotopic revascularization). The animals were sacrificed after the MR examination, and comparisons were made among the MR images, macroscopic observations, and histologic sections. RESULTS: All transplants were clearly identifiable on the MR images; they produced slight-to-moderate narrowing of the airway diameter. Enhancement of the transplant tissues was clearly present. There was close correspondence between the MR morphology and the macroscopic and histologic sections. CONCLUSION: MR imaging can be used to monitor in vivo tracheal transplantation after heterotopic revascularization.

Anastomosis, Surgical↗