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Biomedical subjects

L Spelle

Publications and source records attributed to L Spelle.

29 records · Page 2Linked to original sources
PubMed1999

[Vertebro-epidural lumbosacral vascular malformations. An unusual cause of lumbo-sciatic pain].

Sciatica is most commonly caused by nerve root compression secondary to herniated disk. Rarely, it can be due to a lumbosacral vascular malformation. We present five cases with such a malformation, presenting as a chronic lumboradiculagia. The patients were explored with computed tomography, MRI and selective spinal angiography. Polymorphic anatomic and hemodynamic aspect of these cases are reported: 1. One vertebral hemangioma with epidural extension; 2. Three purely epidural malformations: a) one epidural cavernous hemangioma, b) one epidural arteriovenous malformation, c) one epidural varix; 3. One paravertebral arteriovenous fistula with epidural venous drainage. Diagnosis of these rare malformations may be difficult. A multiplanar cross-sectional magnetic resonance and computed tomography scan with contrast enhancement can show characteristic abnormalities and may assist in recognition these malformations. Selective spinal angiography confirms the diagnosis, allows to classify the malformation and is required to evaluate endovascular therapeutic possibilities.

Adolescent↗
PubMed1998

[MRI cholangiography with rapid spin-echo technique: prospective evaluation of 20 patients].

PURPOSE: To evaluate a MR cholangiographic technique using a non breath-hold fast spin-echo technique in patients with suspected bile duct obstruction. MATERIAL AND METHODS: Twenty patients with suspected bile duct obstruction were prospectively investigated with MR cholangiography using a T2-weighted non breath-hold fast spin-echo technique (TR = 8000-9000 mse, effective TE = 120-266 msec, ETL = 16-32, acquisition time = 1-3 min) with a body coil. Results of MR cholangiography were compared to those obtained with endoscopic retrograde cholangiography (n = 20 patients) and endoscopic sonography (n = 12 patients) that were considered as reference. RESULTS: MR cholangiography provided high-quality images in 19 out of 20 cases (95%). MR cholangiography had 100% sensitivity, 100% specificity and 100% accuracy in the diagnosis of bile duct dilation. MR cholangiography had 73% sensitivity, 75% specificity and 73% accuracy in the diagnosis of bile duct obstruction. MR cholangiography failed to depict small stones (< 3 mm) of the main bile duct in 4 cases in which no bile duct dilatation was found. CONCLUSION: MR cholangiography using a non breath-hold fast spin-echo technique depicts bile duct dilatation with a degree of accuracy comparable to that achieved with endoscopic examination. In the absence of bile duct dilatation, small stones of the main bile duct may be undetected with MR cholangiography.

Adult↗
PubMed1998

Endovascular treatment of basilar tip aneurysms after direct puncture of the vertebral artery.

Basilar aneurysms that are not amenable to standard endovascular treatment via the femoral approach because catheterization is difficult pose a rare but serious problem. We present two cases of basilar tip aneurysms successfully treated by the endovascular route after direct puncture of the right vertebral artery. In both patients, the left vertebral artery was tortuous, small, and irregular, and the ostium of the right vertebral artery was not accessible by the femoral approach.

Catheterization, Peripheral↗
PubMed1997

T1-weighted spoiled gradient-echo MR imaging of focal hepatic lesion: comparison of in-phase vs opposed-phase pulse sequence.

The goal of our prospective study was to compare quantitatively and qualitatively in-phase and opposed-phase T1-weighted breath-hold spoiled gradient-recalled-echo (GRE) MR imaging technique for imaging focal hepatic lesion. Thirty-eight patients with 53 focal hepatic lesions had in-phase (TR = 12.3 ms, TE = 4.2 ms) and opposed-phase (TR = 10.1 ms, TE = 1.9 ms) GRE (flip angle = 30 degrees , bandwidth +/- 32 kHz, matrix size 256 x 128, one signal average) MR imaging at 1.5 T. Images were analyzed quantitatively by measuring the lesion-to-liver contrast and for lesion detection. In addition, images were reviewed qualitatively for lesion conspicuity. Quantitatively, lesion-to-liver contrast obtained with in-phase (3. 22 +/- 1.86) and opposed-phase pulse sequence (3.72 +/- 2.32) were not statistically different (Student's t-test). No difference in sensitivity was found between in-phase and opposed-phase pulse sequence (31 of 53, sensitivity 58 % vs 30 of 53, sensitivity 57 %, respectively). Two lesions not seen with opposed-phase imaging were detected with in-phase imaging. Conversely, one lesion not seen on in-phase imaging was detected on opposed-phase imaging so that the combination of in-phase and opposed-phase imaging yielded detection of 32 of 53 lesions (sensitivity 60 %). Qualitatively, lesion conspicuity was similar with both techniques. However, in-phase images showed better lesion conspicuity than opposed-phase images in 9 cases, and opposed-phase images showed better lesion conspicuity than in-phase images in 7 cases. No definite advantage (at a significant level) emerged between in-phase and opposed-phase spoiled GRE imaging. Because differences in lesion conspicuity and lesion detection may be observed with the two techniques in individual cases, MR evaluation of patients with focal hepatic lesion should include both in-phase and opposed-phase spoiled GRE imaging.

Adult↗
PubMed1997

Parametric images of benzodiazepine receptor concentration using a partial-saturation injection.

The in vivo quantification of the benzodiazepine receptor concentration in human brain using positron emission tomography (PET) and 11C-flumazenil (11C-FMZ), is usually based on a three-compartment model and on PET curves measured in a small number of large regions of interest; however, it should be interesting to estimate the receptor concentration for each pixel and to build quantified images of the receptor concentration. The main advantage is to allow screening of the receptor site localization and visual observation of the possible abnormalities. Up to now, all the methods described include complex experimental protocols, difficult to use in routine examinations. In this paper, we propose the partial-saturation approach to obtain parametric images of benzodiazepine receptor concentration and FMZ affinity. It consists of a single FMZ injection with a low specific activity, followed by Scatchard analysis. Like other parametric imaging methods, this partial-saturation approach can lead to a small percentage (< 1%) of unrealistic values in receptor-poor regions; however, it is the only method that allows receptor concentration and affinity images to be obtained from a single-injection 40-min experiment without blood sampling. We also propose a second method in which the receptor concentration map is directly deduced from the PET image acquired 5 to 10 min after a partial-saturation injection. This method assumes a known and constant FMZ affinity value but requires only very simple corrections of this PET image. It is robust (negative values are never found) and quite simple to use in routine examination of patients (no blood sampling, single injection, only 10-min experiment).

Brain Chemistry↗
PubMed1997

Non-breath-hold fast spin-echo versus breath-hold fast spin-echo and spoiled gradient-recalled echo MR imaging in the detection of hepatic tumors: correlation with surgical findings.

OBJECTIVE: Our objective was to compare the sensitivity of non-breath-hold T2-weighted fast spin-echo with and without fat suppression, breath-hold T2-weighted fast spin-echo without fat suppression, and spoiled gradient-recalled echo (GRE) MR imaging for detecting hepatic tumors using surgical findings as the standard of reference. SUBJECTS AND METHODS: Eighteen patients with 36 surgically proven hepatic tumors had non-breath-hold T2-weighted fast spin-echo (6000/117 [TR/effective TE; echo train length, 16) MR imaging with and without fat suppression, breath-hold T2-weighted fast spin-echo MR imaging (2700/105; echo train length, 20), and spoiled GRE images (10.1/1.9; flip angle, 30 degrees) obtained before and after injection of a gadolinium chelate. Images were analyzed separately by two independent readers, with disagreements resolved by consensus reading. RESULTS: Non-breath-hold T2-weighted fast spin-echo MR imaging with and without fat suppression depicted 22 (61%; 95% confidence interval [CI], 43-77%) and 20 (56%; 95% CI, 37-72%) of 36 hepatic tumors, respectively. Breath-hold T2-weighted fast spin-echo imaging allowed detection of 19 (53%; 95% CI, 35-69%) of 36 hepatic tumors. Unenhanced and gadolinium chelate-enhanced spoiled GRE images allowed depiction of 18 (50%; 95% CI, 33-67%) and 29 (81%; 95% CI, 63-91%) of 36 hepatic tumors, respectively. Gadolinium chelate-enhanced spoiled GRE images allowed depiction of significantly more hepatic tumors than any of the other pulse sequences. CONCLUSION: Gadolinium chelate-enhanced spoiled GRE imaging is more sensitive than T2-weighted MR imaging obtained with a breath-hold or a non-breath-hold technique.

Contrast Media↗
PubMed1997

Nontumorous hepatic pseudolesion around the falciform ligament: prevalence on gadolinium chelate-enhanced MR examination.

OBJECTIVE: Our objective was to determine the prevalence of nontumorous hepatic pseudolesions seen around the falciform ligament on dynamic spoiled three-dimensional (3D) gradient-recalled echo (GRE) MR imaging obtained during i.v. injection of a gadolinium chelate. SUBJECTS AND METHODS: The gadolinium chelate-enhanced spoiled 3D GRE examinations of the liver of 103 patients were prospectively analyzed by two readers for the presence of a nontumorous hepatic pseudolesion around the falciform ligament to determine the prevalence of this finding. For all pseudolesions, pathologic examination or follow-up imaging studies excluded true tumors. RESULTS: A total of 15 nontumorous hepatic pseudolesions were found on 13 (13%) of 103 examinations. The size of pseudolesions ranged from 5 to 15 mm (mean, 9 mm). Twelve pseudolesions were located in segment IV, and three were in segment III. On two MR examinations, two pseudolesions (one in segment IV and one in segment III) were found. Fourteen (93%) of 15 pseudolesions were seen during the arterial phase of the bolus injection. All pseudolesions (100%) were seen during the portal phase, and one pseudolesion (7%) remained visible during the equilibrium phase. The presence of true tumors was excluded in one case by pathologic examination and in twelve cases by follow-up imaging examinations. CONCLUSION: Nontumorous hepatic pseudolesions around the falciform ligament are not rarely seen on gadolinium chelate-enhanced spoiled 3D GRE examinations. Thus, recognition of these pseudolesions is crucial because they may be misinterpreted as true tumors.

Adult↗
PubMed1996

Quantitation of benzodiazepine receptors in human brain using the partial saturation method.

UNLABELLED: The in vivo quantification of the benzodiazepine receptor concentration in humans using PET and flumazenil (FMZ) is usually based on Scatchard analysis when the goal is to avoid blood sampling. The experimental protocols, however, include several (at least two) experiments with various specific activities in the same subject to obtain a range of bound ligand concentrations. METHODS: We propose the partial saturation method, which is based on a natural decrease in bound ligand concentration after an FMZ injection with an average dose between a tracer dose and a saturation dose. An adequate range of bound ligand concentrations can thus be obtained from a single experiment. The free ligand concentration is estimated from the PET measurement in the pons after correction for the effect of the small receptor site concentration in this reference region. RESULTS: The receptor concentration and affinity estimates obtained with this approach in six regions of interest agree with previously published values obtained by using more complex approaches. Receptor concentration appears to be insensitive to the uncertainties with regard to the receptor site concentration in the pons. CONCLUSION: The partial saturation protocol can be used to estimate both the benzodiazepine receptor concentration and the FMZ affinity in routine examinations in adults (or even in children) using a single 40-min experiment without blood sampling.

Adult↗