Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.     

Half-fourier acquisition single-shot turbo spin-echo (HASTE) MR: comparison with fast spin-echo MR in diseases of the brain

PURPOSE: To compare an ultrafast T2-weighted (half-Fourier acquisition single-shot turbo spin-echo [HASTE]) pulse sequence with fast spin-echo T2-weighted sequences in MR imaging of brain lesions. METHODS: Fast spin-echo and HASTE images of 34 consecutive patients over the age of 50 years or with suspected demyelinating disease were reviewed independently by two neuroradiologists for the number of lesions less than 5 mm and greater than or equal to 5 mm, and for lesion conspicuity, gray-white matter differentiation, and extent of periventricular confluent signal abnormality. The reviewers also assessed for the presence of hemosiderin and extent of motion artifacts. RESULTS: Per patient, the mean number of 5-mm or larger lesions detected on fast spin-echo images (1.4) relative to the number detected on HASTE images (0.8) was not statistically significant. For lesions less than 5 mm, fast spin-echo images showed more lesions (7.5) than HASTE images did (2.4). The fast spin-echo images were better at depicting gray-white matter differentiation, conspicuity of lesions, and periventricular signal abnormality. Of four T2 hypointense lesions seen on fast spin-echo images, none was detected on HASTE images. CONCLUSION: Although the HASTE technique might be useful for rapid imaging of the brain, our study shows a diminished sensitivity for the detection of lesions less than 5 mm in diameter and for T2 hypointense lesions.     

Studies on the antiviral mechanisms of protein kinase inhibitors K-252a and KT5926 against the replication of vesicular stomatitis virus

INTRODUCTION: We investigated the accuracy of MRI of the prostate with an endorectal surface coil in determing penetration of the prostatic capsule and invasion of seminal vescicles in prostate carcinoma. MATERIAL AND METHODS: Endorectal coil MRI (1 Tesla) was performed in 300 patients with biopsy-proved cancer. The PSA levels were always calculated and all the patients were examined with transrectal ultrasound. The imaging protocol included Turbo Spin Echo T2-weigthed (3900/150 TR/TE) axial and coronal images and T1-weigthed (650/15 TR/TE) axial images, 4 mm thick interleaved sections with .4 mm intersection gap, FOV 180 mm, 256 x 256 matrix (reconstruction 512). Seventy-five patients underwent radical prostatectomy and MR images were compared with pathologic findings of capsular penetration and invasion of seminal vescicles. The MR signs specific for capsular penetration were: deformation (irregularity) of capsular profile, capsular retraction with irregular margins, capsular interruption, obliteration of periprostatic adipose tissue, asymmetry of neurovascular bundles. RESULTS: MRI correctly depicted 37 of 45 pathologic stage T2 lesions and correctly depicted macroscopic capsular penetration (T3) in 18 of 23 cases. Microscopic capsular penetration was overestimated in all 7 cases. Sensitivity, specificity, accuracy, for microscopic and macroscopic capsular penetration were 60, 82, 73% respectively. Sensitivity, specificity, accuracy for macroscopic capsular penetration were 78, 82, 80% respectively. Sensitivity, specificity, accuracy for depiction of seminal vesicle involvment were 80, 100, 93%, respectively. The most reliable signs of capsular penetration were capsular interruption and invasion of periprostatic adipose tissue, while asymmetry of the neurovascular bundle was not seen. CONCLUSIONS: MRI provides accurate preoperative local staging. The two main limitations of MRI were the high rate of microscopic capsular penetration and the difficulty in detecting capsular penetration of tumor when the lesions are in the prostate apex. Prostate enlargement also made diagnosis more difficult.     

CT and MRI of experimentally induced mesenteric ischemia in a porcine model

OBJECTIVE: Our goal was to assess the value of CT and MRI for the detection of bowel wall changes in experimentally induced mesenteric ischemia. METHODS: in 18 female pigs, a percutaneous embolization of the superior mesenteric artery was performed with buthyl-2-cyanoacrylate and Lipiodol (1:1) (experimental group). In six animals, only diagnostic imaging and histologic evaluation were performed (control group). CT was carried out 3, 6, and 12 h after occlusion. Incremental CT (1 s scan time, 5 mm slice thickness, 7 mm increment, 120 kV/290 mAs) and spiral CT (slice thickness 5 mm, pitch 1.5, 120 kV/165 mA) were performed pre and post contrast injection (Somatom Plus/Siemens). Serial CT was carried out after intravenous contrast injection (1 ml/kg, 2 ml/s). MRI (Magnetom 1.5 T; Siemens) was performed with T1 (pre and post 0.01 mmol/kg Gd-DTPA; Magnevist; Schering, Germany), T2, and proton density images in axial orientation. Slice thickness was 3 mm and slice gap 1 mm. Additionally, a T1-weighted GE sequence (multislice FLASH 2D) was obtained in dynamic technique (before and 30, 60, and 90 s after contrast agent injection) with a slice thickness of 5 mm. Biometrical monitoring included blood pressure, heart frequency, blood cell count, electrolyte status, blood gas analysis, and determination of serum lactate. Image evaluation included morphological analysis and determination of the enhancement pattern. Histological specimens were obtained and analyzed according to the Chiu classification. RESULTS: The histologic workup of the specimen 3, 6, and 12 h after vascular occlusion revealed an average Chiu state 3, 4, and 5. On CT, the bowel wall had a thickness of 4.7 mm on average in the ischemic segments. There was a significant difference from the control group (average 3 mm). Free intraperitoneal fluid and intramural gas were seen after 12 h of ischemia in 80%. In ischemic bowel segments, no mural enhancement was seen. Normal segments and the bowel of the control animals showed an enhancement of 34 HU on average (SD = 3.1 HU; p.<0.01). In MRI, S/N and C/N differed significantly between experimental and control groups in T1 and proton density images. In ischemic segments of all phases, the bowel wall did not show contrast enhancement. Healthy segments and bowel of control animals showed a significant enhancement (p<0.01). CONCLUSION: Cross-sectional imaging has a high sensitivity for delineation of ischemic bowel wall segments. The enhancement pattern of the bowel wall enables detection of location, extent, and cause of a acute arterial mesenteric ischemia with high accuracy in an early phase.     

Molecular heterogeneity and new subtypes of HCV genotype 4

We used five MRI sequences in six patients with multiple sclerosis (MS): conventional spin-echo (CSE) with 5-mm slices; 2D fast spin-echo (FSE) with 2-mm slices; multishot T2*-weighted echo-planar imaging (EPI) with 5-mm slices; fast fluid-attenuated inversion recovery (fFLAIR) with 2-mm slices; and 3D fast spin-echo with 1.5-mm-thick slices. A total of 225 lesions were detected on CSE, 274 on 2D FSE, 137 on EPI, 385 on fFLAIR and 320 on 3D FSE. The EPI sequence was clearly the least sensitive and susceptibility artefact was a problem, particularly in the brain stem and temporal lobes. Fast FLAIR displayed a much higher number of supratentorial lesions (380) than 3D FSE (297), 2D FSE (264) or CSE (211). However, in the posterior cranial fossa 3D FSE was the most sensitive sequence (23 lesions), followed by CSE (14) and 2D FSE (10), while fFLAIR (5) was extremely insensitive.     

Lesion volume measurement in multiple sclerosis: how important is accurate repositioning?

This study was designed to estimate the contribution of repositioning inaccuracies to measured intracranial lesion volumes in multiple sclerosis (MS). Five patients with MS were each scanned 10 times, using spin-echo imaging (2,000/34/90), contiguous 5-mm slices, and different scanning positions. The maximum displacements from baseline were +/-4 degrees (AP rotation) and 3 mm (slice offset). Lesion volume was measured twice for each scan using a semiautomated contour technique. Measured lesion volumes ranged from 4,328 mm3 to 164,831 mm3. The mean intrarater coefficient of variation (CV) calculated for individual patients ranged from 1.1 to 4% (median, 1.7%). Using analysis of variance, the overall variance and CV due to altered scan position were greater than that due to rater error (repositioning CV 4.0%, intrarater CV 3.5%). The worst-case difference between volumes in the same patient ranged from 8.9 to 32% (median, 9.9%). Both rater and repositioning errors were greater for smaller lesion volumes. The maximum potential error due to repositioning inaccuracies is of a similar magnitude to the 5 to 10% expected change in lesion volume over 1 year. This study justifies continued careful attention to accuracy in repositioning for serial MR studies in patients with MS.     

Three-dimensional display of the bronchi using helical CT

The purpose of this study was to evaluate the clinical usefulness of three-dimensional (3D) images of the bronchi obtained using helical CT. Thirteen patients with lung cancer, one with tracheal diverticulum, and one with bronchial amyloidosis were examined. The CT scanner employed was the Toshiba Xforce. The helical CT scan cycle consisted of 20 continuous rotations, each requiring 1.5 sec, for a total scanning time of 30 sec. Scans were obtained using a 5-mm X-ray beam width, a 5-mm/1.5 sec couchtop sliding speed, and a 2-mm reconstruction interval. 3D images were reconstructed using a CEMAX VIPstation. The optimal lower and upper threshold CT values for 3D images of the bronchi were -650 and -100 HU, respectively, and 3D images clearly depicted endobronchial lesions. Cartilage crescents were also demonstrated, but longitudinal and circular mucosal folds could not be visualized. In conclusion, 3D images of the bronchi acquired using helical CT were useful in evaluating endobronchial lesions.     

Role of high-resolution pinhole tomography in the evaluation of thyroid abnormalities

The present study was undertaken to evaluate the contribution of pinhole-single photon emission computed tomography (P-SPECT) to scintigraphy of the thyroid gland. Thirty-six patients, referred for thyroid scintigraphy because of palpatory or ultrasonographic findings, were studied after intravenous administration of technetium-99m pertechnetate (222 MBq) using a rectilinear scanner and a single-headed rotating gamma camera equipped with a pinhole collimator. P-SPECT study was acquired on a 128 x 128 matrix, in 30 projections over 180 degrees and an acquisition time of 40 seconds per step. After transaxial reconstruction, coronal slices were compared with planar views obtained by the scanner. The size of the thyroid gland obtained by P-SPECT matched the life-size image of a rectilinear scan, and it clearly delineated the shape and borders of two huge multinodular glands. Its major contribution was in its improved resolution. Pinhole-SPECT identified 21 foci not visualized on planar views, 19 cold lesions, and 2 "warm" nodules embedded in normal tissue of 13 patients. Furthermore, it clearly delineated 18 discrete ill-defined nodules of 13 patients, (single in 4 patients and multiple in 9 patients): 16 cold lesions, and 2 hot foci. When a distinct palpable nodule was present, whether cold (22 lesions) or hot (2 foci), SPECT was of no additional diagnostic value. However, when the palpable nodule was a toxic one, the contralateral suppressed lobe was visible on SPECT only. Two ultrasonographic findings, of 3- and 5-mm in diameter, were neither identified on planar views nor on P-SPECT. In conclusion, P-SPECT of the thyroid gland improves delineation of huge multinodular glands and detection of small nodules (within the resolution of the camera) that could otherwise have been overlooked on planar views of a thyroid scanner. It allows for definition of tracer uptake in tiny discrete nodules and in multinodular goiter, and is a better guide to the physician in fine-needle aspiration of the cold areas.     

Effects of heart rate on vulnerability to fibrillation in a computer model

The SET-2400W is a newly designed whole-body PET scanner with a large axial field of view (20 cm). Its physical performance was investigated and evaluated. The scanner consists of four rings of 112 BGO detector units (22.8 mm in-plane x 50 mm axial x 30 mm depth). Each detector unit has a 6 (in-plane) x 8 (axial) matrix of BGO crystals coupled to two dual photomultiplier tubes. They are arranged in 32 rings giving 63 two-dimensional image planes. Sensitivity for a 20-cm cylindrical phantom was 6.1 kcps/kBq/ml (224 kcps/microCi/ml) in the 2D clinical mode, and to 48.6 kcps/kBq/ml (1.8 Mcps/microCi/ml) in the 3D mode after scatter correction. In-plane spatial resolution was 3.9 mm FWHM at the center of the field-of-view, and 4.4 mm FWHM tangentially, and 5.4 mm FWHM radially at 100 mm from the center. Average axial resolution was 4.5 mm FWHM at the center and 5.8 mm FWHM at a radial position 100 mm from the center. Average scatter fraction was 8% for the 2D mode and 40% for the 3D mode. The maximum count rate was 230 kcps in the 2D mode and 350 kcps in the 3D mode. Clinical images demonstrate the utility of an enlarged axial field-of-view scanner in brain study and whole-body PET imaging.     

Structure and organization of the human uncoupling protein 2 gene and identification of a common biallelic variant in Caucasian and African-American subjects

PURPOSE: We evaluated the intraobserver and interobserver variability in measuring long-term changes in the volume of brain lesions on 5- and 3-mm-thick MR sections in patients with multiple sclerosis. METHODS: Eighteen 18 patients were scanned on two separate occasions with a mean interval of 16.4 months between the two examinations. In each session, a scan with 24 contiguous 5-mm-thick axial sections and another with 40 contiguous 3-mm-thick axial sections was acquired consecutively without moving the patient. We assessed MR lesion load by using a semiautomated local thresholding technique. RESULTS: Lesion volume was significantly higher on images with 3-mm-thick sections than on those with 5-mm-thick sections both at baseline and at follow up. Significant increases in total lesion volume were observed during the follow-up period on images obtained with both 5- and 3-mm-thick sections. The intra- and interobserver variability in measurements of changes in lesion volume was significantly higher on images with 5-mm-thick sections than on those with 3-mm-thick sections. CONCLUSION: Our data indicate that the acquisition of thinner sections increases the reliability of the assessment of changes in brain lesion load on MR images in patients with multiple sclerosis.     

Hypoxia-tolerant neonatal CA1 neurons: relationship of survival to evoked glutamate release and glutamate receptor-mediated calcium changes in hippocampal slices

Neurons in the neonatal mammalian brain survive greater degrees of hypoxic stress than those in the mature brain. To investigate how developmental changes in glutamate receptor-mediated neurotoxicity contribute to this difference, we measured hypoxia-evoked glutamate release, glutamate receptor contribution to hypoxia-evoked intracellular calcium changes, and survival of hypoxia-/ischemia-sensitive CA1 neurons in rat hippocampus. Glutamate release was measured by a fluorescence assay, calcium changes in CA1 neurons with fura-2, and cell viability using Nissl and fluorescence staining with calcein-AM/ethidium homodimer, all in 300-micron thick hippocampal slices from 3-30 post-natal day (PND) rats. Glutamate released from PND 3-7 slices during hypoxia (PO2 = 5 mmHg) was only one third that of PND 18-22 slices. In PND 3-7 slices, survival of CA1 neurons after 5 min of hypoxia and 6 h of recovery was significantly greater than in PND 18-22 slices (viability indices 0.60 and 0.28, respectively, (p < 0.05). Five min of anoxia significantly altered Nissl staining pattern and morphology of CA1 neurons in PND 18-22 but not PND 3-7 slices. Hypoxia (PO2 = 5 mm Hg) caused three to five times greater increases in [Ca2+]i in PND 18-22 slices than in PND 3-7 slices (p < 0.001). During re-oxygenation, [Ca2+]i returned to baseline in PND 3-7 slices, but remained elevated in PND 18-22 slices. Glutamate receptor-mediated calcium changes in CA1 during hypoxia were 33% and 62% of the total calcium change in PND 3-7 and PND 18-22 CA1, respectively. We conclude that survival of CA1 neurons in PND 3-7 slices following hypoxic stress is associated with smaller increases and enhanced recovery of [Ca2+]i, less accumulation of glutamate, and less glutamate receptor-mediated calcium influx than in PND 18-22 slices.     

Pre-operative classification of abdominal aortic aneurysms with spiral CT: the axial source images revisited

OBJECTIVE: The differentiation of supra-, juxta- and high infrarenal abdominal aortic aneurysms (AAA), which is essential for good surgical management, remains problematic. This prospective study assessed the value of highly overlapping vs. contiguous axial spiral computed tomography (CT) reconstructions in the pre-operative assessment of AAA. PATIENTS AND METHODS: Thirty-five patients with abdominal aortic aneurysms were studied with spiral CT (10 mm collimation, pitch 1). Axial reconstructions were performed at 2 and 10 mm increments and compared with surgical findings. Using each protocol, the aneurysms were classified as infra-, juxta- or suprarenal. Observers also assessed visualization of main and accessory renal artery origins and identification of other surgically relevant vascular anomalies. RESULTS: The 2 mm protocol correctly identified 29/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; two infrarenal aneurysms were overestimated as suprarenal. The 10 mm protocol correctly classified 25/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; five infrarenal aneurysms were overestimated as juxtarenal (n = 3) or suprarenal (n = 2) and one case was equivocal. Correct classification was thus 94% using the 2 mm protocol and 83% with the 10 mm protocol (P = 0.063). All 70 main renal artery origins were visualized with the 2 mm protocol, while the 10 mm protocol missed six (P = 0.03) The 2 mm protocol identified 10 accessory renal arteries, four of which were missed by the 10 mm protocol. Both protocols demonstrated five surgically relevant venous anomalies. CONCLUSION: Spiral CT with highly overlapping axial reconstructions correctly classified 94% of abdominal aortic aneurysms; overlapping reconstructions were particularly useful in differentiating high infrarenal from juxtarenal aneurysms.     

Incidence of very mild to severe dementia and Alzheimer''s disease in Denmark: the Odense Study

A scintigraphic model of the lungs was used to study the threshold of detection of diffuse disease of the lungs. METHODS: Randomly distributed cold lesions of 4, 8, 12 and 16 mm3 block sizes were created, occupying 0%-50% of lung tissue in steps of 1%. These were submitted for reporting to five observers each with a normal study for comparison. RESULTS: No observer detected lesions of 4-mm3 block size even when up to 50% of the lung was involved. All observers detected lesions of 8-mm3 block size when a mean of 27% of lung tissue was involved with lesions. As lesion size increased to 12 and 16 mm3, observers detected lesions when a mean of 10% and 6% of lung tissue was involved, respectively. Comparison between views for each observer showed that the lateral and anterior oblique views were used more often than the anterior, posterior oblique and posterior views. CONCLUSION: This model suggests that pulmonary scintigraphy has the potential to detect a diffuse disease such as emphysema at an early stage of lung involvement. In general, small anatomic lesions appear to have more profound scintigraphic consequences. However, even scintigraphic lesions of the order of size of the pulmonary acinus are easily detected.     

FDG PET and dual-head gamma camera positron coincidence detection imaging of suspected malignancies and brain disorders

The purpose of the study was to compare the diagnostic accuracy of fluorodeoxyglucose (FDG) images obtained with a dual-head coincidence gamma camera (DHC) with those obtained with a dedicated PET in a series of 26 patients. METHODS: Nineteen patients with known or suspected malignancies and 7 patients with neurological disorders underwent PET imaging after injection of approximately 10 mCi of FDG. Whole-body imaging was performed on 19 patients and brain imaging on 7 patients. DHC images were then acquired for 30 min over the region of interest using a dual-head gamma camera equipped with 3/8-in.-thick NaI(TI) crystals and parallel slit-hole collimators. The images were reconstructed in the normal mode, using photopeak/photopeak, photopeak/Compton and Compton/photopeak coincidence events. RESULTS: Although the spatial resolutions of PET with a dedicated PET scanner and of DHC are in the same range, the lesion detectability remains superior with PET (4 mm for PET versus 13.5 mm for DHC in phantom experiments) with a contrast ratio of 5:1. This is most probably attributable to the higher sensitivity of PET (2238 coincidences/min/microCi for PET versus 89 coincidences/min/microCi for DHC). The pattern of uptake and interpretation for brain imaging was similar on both PET and DHC images in all patients. In the 19 oncology patients, 38 lesions ranging from 0.7 to 5 cm were detected by PET. DHC imaging detected 28 (73%) of these lesions. Among the 10 lesions not seen with DHC, 5 were less than 1.2 cm, 2 were located centrally within the liver and suffered from marked attenuation effects and 3 were adjacent to regions with high physiological activity. The nondetectability of some lesions with DHC compared with PET can be explained by several factors: (a) start of imaging time (mean+/-SD: 73+/-16 min for PET versus 115+/-68 min for DHC, leading to FDG decay to 6.75 mCi for PET and 5.2 mCi for DHC); (b) limited efficiency of a 3/8-inch-thick Nal(TI) crystal to detect 18F photons; (c) suboptimal two-dimensional reconstruction algorithm; and (d) absence of soft-tissue attenuation correction for centrally located lesions. CONCLUSION: FDG DHC imaging is a promising technique for oncological and brain imaging.     

Gender comparison of peak oxygen uptake: repetitive box lifting versus treadmill running

The gender differences in peak oxygen uptake (VO2peak) for various modes of exercise have been examined previously; however, no direct gender comparisons have been made during repetitive lifting (RL). In the present study the VO2peak between RL and treadmill running (TR) was compared between 20 men [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.79 (0.06) m, 81 (9) kg, 19 (6)%, respectively] and 20 women [mean (SD) age, height, body mass and body fat: 21 (3) years, 1.63 (0.05) m, 60 (7) kg, 27 (6)%, respectively]. VO2peak (l x min[-1]), defined as the highest value obtained during exercise to volitional fatigue, was determined using discontinuous protocols with treadmill grade or box mass incremented to increase exercise intensity. For RL VO2peak, a pneumatically driven shelf was used to lower a loaded box to the floor, and subjects then lifted the box, at a rate of 15 lifts x min(-1). VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and minute ventilation (VE, l x min[-1]) were determined using an on-line gas analysis system. A two-way repeated measures analysis of variance revealed significant gender effects, with men having higher values for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE, but women having higher values of the ventilatory equivalent for oxygen (VE/VO2). There were also mode of exercise effects, with TR values being higher for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE and an interaction effect for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]) and VE/VO2. The women obtained a greater percentage (approximately 84%) of their TR VO2peak during RL than did the men (approximately 79%). There was a marginal tendency for women to decrease and men to increase their VE/VO2 when comparing TR with RL. The magnitude of the gender differences between the two exercise modalities appeared to be similar for heart rate, VE and R, but differed for VO2peak (l x min(-1) and ml x kg(-1) x min[-1]). Lifting to an absolute height (1.32 m for the RL protocol) may present a different physical challenge to men and women with respect to the degree of involvement of the muscle groups used during lifting and ventilation.     

A microcholangiographic study of liver disease models in rats

RATIONALE AND OBJECTIVES: Rats develop hepatobiliary injury due to small bowel bacterial overgrowth (SBBO) that, at specimen, resembles cholangiography sclerosing cholangitis. To better visualize the smaller bile ducts, we used microcholangiography to determine the spectrum of biliary lesions in this and five other models of liver disease. METHODS: The models studied were as follows: (1) Surgically created jejunal, self-filling blind loops induce SBBO. (2) Intraperitoneal injection of a bacterial cell wall polymer, peptidoglycan-polysaccharide (PG-PS), causes granulomatous hepatitis. (3) Intraperitoneal injection of endotoxin (lipopolysaccharide) causes sinusoidal congestion and shock. (4) Bile duct ligation induces bile duct proliferation. (5) Alpha-naphthyl-isothiocyanate (ANIT) induces bile duct proliferation. (6) Carbon tetrachloride (CCl4) causes fibrosis and cirrhosis. Warmed barium sulfate, gelatin, and saline were injected in the extrahepatic bile duct. Liver slices (2 mm) underwent microradiographic techniques, and images were correlated with histology. RESULTS: Rats with SBBO had irregular and dilated extrahepatic bile ducts with thickened walls. Rats treated with endotoxin and CCl4 had normal microcholangiograms. Bile duct proliferation was identified following ANIT and bile duct ligation. Rats given PG-PS demonstrated irregular intrahepatic bile ducts. Microcholangiograms following SBBO and PG-PS showed similarities including focal ductal dilatation, narrowing, proliferation, and destruction. CONCLUSION: Various models of liver injury induce characteristic cholangiographic appearances. Microcholangiography is useful in examining biliary tract lesions and complements histology.     

The genomic organization of the genes for human lipopolysaccharide binding protein (LBP) and bactericidal permeability increasing protein (BPI) is highly conserved

PURPOSE: The authors evaluated computed tomographic (CT) virtual colography for the detection of simulated polyps under ideal conditions, as well as the effects on lesion conspicuity of (a) collimation, (b) table pitch, and (c) orientation of the colon lumen with respect to the gantry. MATERIALS AND METHODS: Pig colon was resected and cleansed, and polyps with diameters of 3, 7, and 10 mm were created. Each specimen was scanned with collimation of 5 and 7 mm and table pitch of 1.0, 1.6, and 2.0 at angles of 0 degrees, 45 degrees, and 90 degrees to the gantry. The initial two-dimensional (2D) images were reconstructed at 1-mm intervals (2D reconstructions), from which three-dimensional (3D) virtual colography images were generated. Polyp conspicuity on the initial and reconstructed 2D images and the 3D reconstructions was evaluated on a three-point scale: 0 = polyp not depicted, 1 = polyp faintly depicted, and 2 = polyp clearly depicted. RESULTS: The 10-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image and 3D reconstruction without regard to collimation, table pitch, or angle to the gantry. The 7-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image, but conspicuity on 3D reconstructions varied as the imaging parameters varied. The 3-mm-diameter polyp was faintly depicted (grade 1 conspicuity) on the initial and reconstructed 2D images and 3D reconstructions, but conspicuity varied on the 3D reconstructions as the imaging parameters varied. CONCLUSION: CT virtual colography helped detection of small mucosal polyps regardless of the angle of the colon lumen to the gantry at which they were obtained.     

Pulmonary nodules: effect of increased data sampling on detection with spiral CT and confidence in diagnosis

PURPOSE: To compare spiral computed tomography (CT) with interscan spacing of 4-5 mm versus 8-10 mm for detection rate and level of confidence in diagnosis of pulmonary nodules. MATERIALS AND METHODS: Four radiologists (two junior and two senior faculty members) retrospectively reviewed 67 spiral CT studies with one to six nodules per study. Every second image was masked, which resulted in 8-mm sections every 8 or 10 mm; then all images reconstructed every 4 or 5 mm were reviewed. Lesions were classified as definite, probable, or possible. RESULTS: Narrow interscan spacing yielded more lesions overall (583 vs 566, P < .025) and more definite lesions and fewer equivocal lesions (482 vs 431 and 101 vs 135, respectively; P < .055). The greatest effects were in the reduction of possible lesions (50 vs 88, P < .001) and in the reduction of false-positive diagnoses made by less experienced radiologists. CONCLUSION: Increased reconstruction frequency of spiral CT volume data sets improves detection of pulmonary nodules and enhances confidence in the diagnosis.     

Frameless stereotactic lesion contour-guided surgery using a computer-navigated microscope

BACKGROUND: The Zeiss MKM System is a recently developed computerized operating microscope for image-guided neurosurgery. The clinical advantages, reliability, accuracy, and limitations of this technique were investigated. METHODS: Since February 1995, 78 consecutive frameless stereotactic image-guided procedures were performed in 73 patients (30 males, 43 females; mean age, 46.9 years; range, 16-77 years) for tumor surgery (50/64.1%), cavernoma removal (16/20.5%), and functional procedures (12/15.4%). Skin markers (74 cases) or bone markers (4 cases) and a standard imaging protocol (2-mm cranial computed tomography (CCT) in 59 cases/1.5-mm magnetic resonance imaging (MRI) in 19 cases) were used. RESULTS: The main advantages were pre-operative skin incision, craniotomy and corticotomy planning, and determination of lesion boundaries. Useful registration and system reliability were noted in 97% (76/78) of the procedures. A significant improvement in registration accuracy was observed over the test period from a mean of 4.8 mm (SD = 3.36; Cases 1-25) to a mean of 2.2 mm (SD = 0.86; Cases 26-78). This resulted in an improvement in application accuracy from <5 mm in 71% (Cases 1-25) to <2 mm in 95% (Cases 26-78) of cases, and the accuracy led to successful localization of the lesion in every case. Accuracy was reliable at the beginning of every procedure, but degraded to values >5 mm by the end of the procedure in 29% (22/78) of cases. MRI cases achieved higher application accuracy values (2.1 mm mean) than CT cases (3.7 mm mean). CONCLUSIONS: The system offers a reliable alternative to frame-assisted stereotactic craniotomies in lesion targeting, but would need an intraoperative image update for resection guidance.     

High resolution T2 weighted MRI sequence and diagnosis of neurinoma of the VIII

OBJECT: To assess the value of high resolution fast spin echo T2 weighted (HR-FSE T2w) sequence for the diagnosis of acoustic neuroma. Two criteria for normality of the HR-FSE T2w examination are defined. PATIENTS AND METHODS: 114 patients underwent MR imaging at 1.5 T. The protocol included: axial images; 2 overlapped sequences focused on the internal auditory meatus (IAM), HR-FSE T2w acquisition (512 matrix, 3 mm sections with 1.5 mm overlapping); pre and postcontrast T1 weighted sequences focused on IAM. We defined two criteria for a normal HR-FSE T2w image: cerebellospinal fluid visible throughout the IAM, cochleo-vestibular and facial nerves visible in the IAM. RESULTS: 31 examinations were abnormal with HR-FSE T2w sequence, 25 lesions were found on postcontrast T1 weighted sequence (i.e. 6 false-positive results and none false-negative). The sensitivity, specificity and negative predictive value of this HR-FSE T2w sequence were 100%, 97% and 100% respectively. CONCLUSION: the HR-FSE T2w sequence is the first-line method for detecting tumoral lesions of the IAM. If the 2 normality criteria are present on the HR-FSE T2w images, the T1w sequence with gadolinium injection is of no use; the injection of gadolinium remains necessary if only one of these criteria is lacking.