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Biomedical subjects

M Lacrosse

Publications and source records attributed to M Lacrosse.

At least 19 recordsLinked to original sources
PubMed2002

Is a lung perfusion scan obtained by using single photon emission computed tomography able to improve the radionuclide diagnosis of pulmonary embolism?

Planar pulmonary scintigraphy is still regularly performed for the evaluation of pulmonary embolism (PE). However, only about 50-80% of cases can be resolved by this approach. This study evaluates the ability of tomographic acquisition (single photon emission computed tomography, SPECT) of the perfusion scan to improve the radionuclide diagnosis of PE. One hundred and fourteen consecutive patients with a suspicion of PE underwent planar and SPECT lung perfusion scans as well as planar ventilation scans. The final diagnosis was obtained by using an algorithm, including D-dimer measurement, leg ultrasonography, a V/Q scan and chest spiral computed tomography, as well as the patient outcome. A planar perfusion scan was considered positive for PE in the presence of one or more wedge shaped defect, while SPECT was considered positive with one or more wedge shaped defect with sharp borders, three-plane visualization, whatever the photopenia. A definite diagnosis was achieved in 70 patients. After exclusion of four 'non-diagnostic' SPECT images, the prevalence of PE was 23% (n =15). Intraobserver and interobserver reproducibilities were 91%/94% and 79%/88% for planar/SPECT images, respectively. The sensitivities for PE diagnosis were similar for planar and SPECT perfusion scans (80%), whereas SPECT had a higher specificity (96% vs 78%; P =0.01). SPECT correctly classified 8/9 intermediate and 31/32 low probability V/Q scans as negative. It is concluded that lung perfusion SPECT is readily performed and reproducible. A negative study eliminates the need for a combined V/Q study and most of the 'non-diagnostic' V/Q probabilities can be solved with a perfusion image obtained by using tomography.

Adult↗
PubMed2001

Intestinal involvement in Buerger's disease.

Thromboangiitis obliterans characteristically affects small- and medium-sized vessels of the limbs in young smokers. There is some controversy about the existence of visceral localizations of the disease. The case of a patient with a well-established diagnosis of thromboangiitis obliterans who presented with mesenteric ischemia is described and the literature concerning mesenteric involvement in the disease is reviewed.

Extremities↗
PubMed1999

MR imaging of hypervascular liver tumors: timing optimization during the arterial phase.

To analyze the optimal timing strategy for the detection of hypervascular liver tumors during the arterial phase of magnetic resonance (MR) imaging, a test examination after injection of 2 mL of gadopentetate dimeglumine was performed in 47 patients. The time course of the tumor-to-liver contrast-to-noise ratio (CNR) for all studies together was determined relative to the start of injection, the time of peak aortic enhancement, and the time of peak enhancement in the tumor. All studies were grouped together and the highest CNR was transiently observed at the time of peak tumor enhancement. This CNR was significantly higher than those observed at fixed delays after peak aortic enhancement. However, the CNRs at peak tumor enhancement+/-1.5 seconds did not differ significantly from those obtained after peak aortic enhancement. Finally, the CNRs obtained at fixed delays after the start of injection remained significantly lower. In hypervascular liver tumors, a higher CNR can be obtained during the arterial phase when the MR imaging delay is determined relative to the time of peak enhancement in the tumor or the aorta rather than being fixed after the start of contrast material injection. Timing based on the enhancement profile in the tumor rather than in the aorta should be performed only if rapid MR imaging is available with a time resolution of about 1.5 seconds to image the whole liver.

Adenoma↗
PubMed1999

[Radiation exposure and computed tomography].

Computed Tomography (CT) is recognized as a relatively high-dose diagnostic procedure. There is some obscurity in the literature about the doses due to conventional CT, spiral CT and High Resolution Computed Tomography (HRCT) of the chest. Conventional chest CT results in a radiation dose approximately 100 times that of a standard chest film and 10 times that of a mammography; on the other hand, conventional chest CT is safe for the lens and the pelvis (ovaries, testes and uterus). Radiation dose associated with helical CT is potentially lower than the dose associated with conventional CT. HRCT, consisting of 1- to 2- mm thick-sections performed at 10 mm intervals, has an effective radiation dose lower than that of conventional CT, even with high-dose techniques (400 mAs). HRCT scans obtained at reduced milliamperage (40-80 mAs), the so-called "low-dose HRCT technique", may provide satisfactory visualization of lung parenchyma in the majority of cases and is recommended in patients in whom radiation dose is a major concern (pediatric population or young women in order to minimize breast irradiation). The awareness of radiation dose will become increasingly important for both referring physicians and radiologists when determining indications and deciding which types of imaging procedures and specific protocols should be used.

Female↗
PubMed1997

Spiral computed tomography with three-dimensional reconstructions for severe blunt abdominal traumas: a useful complementary tool?

Spiral computed tomography (CT) has proved to be a valuable tool by providing three-dimensional (3D) images of the studied structures. We hypothesized that a more realistic depiction of lesions by 3D CT could be of interest for surgeons who are treating blunt abdominal traumas and lead to less inappropriate triage. A good working relationship between surgeons and radiologists allowed us to perform a 3D CT examination in six patients. In the first patient, the 3D CT accurately demonstrated spleen fragmentation without devascularized fragment. The second patient had complete devascularization of the spleen upper pole. Conservative treatment was pursued for both patients. For the third patient, 3D CT helped us to differentiate peritoneal-perisplenic fluid from subcapsular fluid. The fourth patient had minor spleen injury associated with severe lacerations of the left kidney. 3D CT showed a complete separation of the kidney lower pole. A delayed partial lower nephrectomy was performed. The fifth patient presented a fragmented spleen and transient massive haematuria related to a well-contained laceration of the kidney upper pole that were amenable to nonoperative management. The sixth patient was emergency operated for active bleeding from a fragmented spleen. 3D CT performed 2 months after spleen repair allowed the assessment of the amount of devascularized tissue, as well as the status of the upper abdomen arteries. For haemodynamically stable patients, 3D CT could be a helpful addition to conventional axial CT for quantifying blunt abdominal traumas, for making the choice between nonoperative and operative treatment, but also between emergency and delayed surgical strategy.

Abdominal Injuries↗
PubMed1997

Detection and segmental location of malignant hepatic tumors: comparison of ferumoxides-enhanced gradient-echo and T2-weighted spin-echo MR imaging.

OBJECTIVE: The aim of our prospective study was to compare the values of ferumoxides-enhanced gradient-echo and T2-weighted spin-echo MR imaging for the detection and segmental location of malignant hepatic tumors. SUBJECTS AND METHODS: Eighteen patients underwent ferumoxides-enhanced T2 weighted spin-echo and steady-state gradient-echo imaging before surgery. Intraoperative sonography was used as the reference examination and showed 28 malignant tumors involving 39 of the 144 hepatic segments. The MR images were reviewed independently by two observers who recorded the number of tumors and their segmental location. The results of the segmental location were subjected to receiver-operating-characteristic analysis. Tumor-liver, vessel-liver, and tumor-vessel contrast-to-noise ratios were calculated. RESULTS: Detection on the gradient-echo images did not differ significantly from that on the T2-weighted spin-echo MR images (observers A and B detected 23 and 24 tumors, respectively, on the gradient-echo images; the two observers each detected 22 tumors on the T2-weighted spin-echo images). Segmental localization was significantly better on the gradient-echo images than on the T2-weighted spin-echo images (mean area under the receiver-operating-characteristic curve: 0.974 versus 0.895 for observer A and 0.962 versus 0.906 for observer B, p = .024). The highest contrast-to-noise ratios for vessel to liver and tumor to vessel were obtained on the gradient-echo images and the highest tumor-liver contrast-to-noise ratio was obtained on the T2-weighted spin-echo images. CONCLUSION: In our study, ferumoxides-enhanced gradient-echo imaging was as accurate as T2-weighted spin-echo imaging for revealing malignant hepatic tumors and was superior for showing their segmental location.

Contrast Media↗
PubMed1997

[Mesenteric and portal venous gas in infarction of the small intestine in adults. Apropos of 3 clinical cases. Value of x-ray computed tomography].

Three case reports are presented with mesenteric and portal venous gas secondary to mesenteric infarction. In these patients with ileus, abdominal CT Scan appears as the most reliable diagnosis procedure. It can detect intravascular gas but also abnormalities of the intestinal wall such as intramural gas even without contrast. In mesenteric infarction, mesenteric and portal venous gas are radiological signs which considerably worsen the prognosis.

Aged↗
PubMed1995

[Spiral CT of the bile ducts].

The multiplanar capability of spiral CT improves the evaluation of bile duct lesions. In particular, spiral CT after intravenous administration of a cholangiographic agent (spiral CT cholangiography) provides adequate 2D and 3D images of the bile ducts in patients with normal bilirubin levels. Spiral CT cholangiography may be particularly useful as a noninvasive imaging method to detect biliary anatomic variations and bile duct stones before or after laparoscopic cholecystectomy. This technique does not replace retrograde cholangiography which has therapeutic applications, but might help to select patients who need to undergo invasive procedures such as retrograde cholangiography.

Bile Duct Neoplasms↗
PubMed1995

[Pneumatosis cystoides intestinalis associated with Steinert disease].

We report the case of a 63-year-old patient suffering from myotonic dystrophy, complicated with respiratory insufficiency, who presented a pneumoperitoneum without sign of peritonitis. Diagnosis of pneumatosis cystoides coli was based on CT scan evidence. Given oxygenotherapy and antibiotherapy, the patient rapidly improved. The association between the two affections has, to our knowledge, not been previously described.

Anti-Bacterial Agents↗
PubMed1994

Noninvasive imaging of the biliary tree before or after laparoscopic cholecystectomy: use of three-dimensional spiral CT cholangiography.

OBJECTIVE: The purpose of this study was to determine the feasibility of using three-dimensional spiral CT after IV administration of a cholangiographic agent for noninvasive detection of anatomic variations of the bile ducts and common bile duct stones before or after laparoscopic cholecystectomy. SUBJECTS AND METHODS: Three-dimensional spiral CT cholangiography was performed before laparoscopic cholecystectomy in 24 patients and after surgery in two patients who had recurrent symptoms. After slow infusion of 250 ml of iodipamide, spiral CT was performed. Three-dimensional images of the bile ducts and a secondary reformation through the long axis of the common bile duct were obtained. Visualization of the biliary tract was evaluated by two observers. Detection of anatomic variations and common bile duct stones was assessed in 19 patients for whom a gold standard (operative or retrograde cholangiogram) was available. RESULTS: In all 26 patients, the common bile duct and the confluence of the hepatic ducts were seen on three-dimensional spiral CT cholangiograms, and in 21 patients second- or higher-order branches were also seen. Seven patients had anatomic variations and two had common bile duct stones. These anomalies were proved by operative cholangiography in each case, except for a low junction of the cystic duct and a common bile duct stone, which were shown by retrograde cholangiography. Six of the seven anatomic variations were adequately detected with spiral CT cholangiography, as were the two cases of common bile duct stones. CONCLUSION: Three-dimensional spiral CT cholangiography is a feasible method for noninvasive detection of biliary anatomic variations and common bile duct stones before or after laparoscopic cholecystectomy.

Bile Ducts↗
PubMedDate not supplied

Venous return by the paraumbilical and hepatic veins in case of superior vena cava obstruction.

Pseudolesion in segment IV of the liver is a well-known diagnostic pitfall during arterial portography or even spiral computed tomography (CT) of the liver. It has suggested that this pseudolesion is the result of an abnormality in subsegmental perfusion. We report a case of an early dense contrast enhancement of segment IV of the liver by epigastric and paraumbilical veins in a patient with a superior vena cava obstruction. A pseudolesion in segment IV was observed in this patient on a spiral CT of the liver obtained during the portal phase.

Adult↗
PubMedDate not supplied

Congenital anomalies of the inferior vena cava and left renal vein: evaluation with spiral CT.

PURPOSE: To determine with spiral computed tomography (CT) the incidence and caval location of left renal vein (LRV) variants that may affect inferior vena cava (IVC) filter placement, spermatic vein embolization, and adrenal or renal venous sampling. MATERIALS AND METHODS: Contrast material-enhanced spiral CT scans of 1,014 patients were evaluated for the incidence and configuration of LRV variants and for the distribution of the entrances of these veins into the IVC. RESULTS: In this series, variants detected were as follows: one azygos continuation of the IVC (0.1%), three bilateral IVCs (0.3%), and 102 LRV variants (10%) including 38 retroaortic renal veins (3.7%) and 64 circumaortic venous rings (6.3%). In the retroaortic renal vein group, the distance between the entrance of the LRV into the IVC and the confluence of the iliac veins was +62.5 mm +/- 8.7. In the circumaortic venous ring group, the distance between the entrances of the retroaortic and preaortic limbs into the IVC was -39.0 mm +/- 17.4; the distance between the entrance of the left retroaortic limb into the IVC and the confluence of the iliac veins was +63.2 mm +/- 17.1. CONCLUSIONS: Detailed knowledge of these anomalies is crucial for IVC filter placement, spermatic vein embolization, and adrenal or renal venous sampling.

Adolescent↗
PubMedDate not supplied

3D spiral CT of the tracheobronchial tree.

OBJECTIVE: Because of intrinsic limitations of transverse cross-sectional imaging methods, CT sometimes is insufficient for adequate evaluation of complex tracheobronchial anomalies. This article describes a complementary 3D procedure specifically dedicated to the study of the tracheobronchial tree. MATERIALS AND METHODS: The procedure combines a specific spiral CT acquisition with 2 or 4 mm collimation, 3D surface rendering of the tracheobronchial aerial content, and double obliquity multiplanar reformats directly planned on the 3D virtual object. It was performed in 11 complex cases including 3 stented benign or malignant stenoses and 2 single lung transplantations. RESULTS: Easier understanding of the tracheobronchial status was achieved in all cases. In three cases, the procedure yielded relevant diagnostic information that neither fiberoptic endoscopy nor transverse CT had provided, leading to significant modification of patient management. CONCLUSION: Three-dimensional spiral CT of the bronchial tree with secondary reformation seems suitable in clinical practice for selected cases.

Adult↗
PubMedDate not supplied

Inflammatory pseudotumor of the liver: MRI with mangafodipir trisodium.

Inflammatory pseudotumor of the liver is a rare benign mass that is often misdiagnosed as hepatocellular carcinoma at preoperative imaging. We report a case of inflammatory pseudotumor of the liver with special emphasis on the appearance at MRI after administration of mangafodipir trisodium. On T1-weighted images the lesion was slightly hypointense relative to the liver, and on T2-weighted images it was isointense with a hyperintense capsule. No tumor enhancement was seen on T1-weighted images after administration of mangafodipir trisodium. MRI with mangafodipir trisodium might help to distinguish inflammatory pseudotumor of the liver from hepatocellular carcinoma.

Adult↗
PubMedDate not supplied

Focal nodular hyperplasia: natural course observed with CT and MRI.

PURPOSE: The purpose of this work was to assess the natural course of biopsy-proven focal nodular hyperplasia (FNH). METHOD: Eighteen biopsy-proven FNHs in 14 patients (12 women and 2 men) who were followed for at least 6 months with CT and/or MRI were included in the study. The volume of the lesions was calculated twice by two observers using the summation of areas method. Intra- and interobserver variability was assessed by intraclass correlation coefficients. Longitudinal data analysis was performed with generalized estimating equations. RESULTS: The volume of FNH was stable in 6 cases, decreased in 10 cases, and increased in 2 cases. Intra- and interobserver variability in size measurements was 5-10%. Intraclass correlation coefficients were >0.992. Longitudinal data analysis showed that there was a general trend of lesion regression. CONCLUSION: Long-term follow-up and objective measurements performed in patients with biopsy-proven lesions show that the natural course of FNH is variable. In particular, lesion regression is not rare.

Adolescent↗
PubMedDate not supplied

Usefulness of [99mTC]MIBI and [18F]fluorodeoxyglucose for imaging recurrent medullary thyroid cancer and hyperparathyroidism in MEN 2a syndrome.

We report the case of a MEN 2a patient with a history of medullary thyroid cancer (MTC) treated by total thyroidectomy, who presented an increasing calcitonin level, suggesting tumor recurrence. Conventional radiographic and radionuclide imaging failed to localize the responsible lesions. A planar and tomographic (SPECT) [99mTc]MIBI scan, performed in order to investigate a recent hyperparathyroidism localized a parathyroid adenoma and revealed an abnormal uptake in the left lateral neck region, corresponding to apparently banal lymph nodes on MRI. This abnormal uptake was also observed on a [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) study and was proven to be an uptake in MTC lymph nodes metastases as confirmed by histopathologic analysis. We conclude that, using an adequate acquisition protocol (i.e. SPECT), [99mTc]MIBI scan is potentially able to localize both parathyroid adenoma and recurrent MTC at one and the same time, particularly in case of non-diagnostic conventional imaging techniques. In this setting, the potential usefulness of FDG-PET is also discussed.

Adult↗