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PubMed1989

[Thin-section computed tomography of intrapulmonary metastases after surgical resection of lung cancer].

To evaluate the morphology of small peripheral intrapulmonary metastases of lung cancers, we studied thin-section computed tomography (CT) images of 12 lesions in 5 cases (1 squamous cell carcinoma, and 4 papillary adenocarcinomas). All lesions were resected, and histopathological diagnosis of them was performed in comparison with primary lesions to differentiate multiple primary lung cancers from intrapulmonary metastases. Thin-section CT images showed mildly lobulated nodules in connection with supplying pulmonary vessels, however, indented pleura and vascular convergence were less frequently seen in intrapulmonary metastases in contrast with primary lung cancers. Thin-section CT is helpful for distinguishing multiple primary lung cancers from intrapulmonary metastases in patients with a history of surgical resection for lung cancers.

Adenocarcinoma, Papillary↗
PubMed1993

[The usefulness of computerized axial tomography (CT) in establishing the composition of calculi].

Determining stone composition before extracorporeal lithotripsy can be potentially useful. A total of 90 calculi of 6 different chemical composition (calcium oxalate monohydrate, calcium oxalate dihydrate, magnesium ammonium phosphate, phosphate carbonate, uric acid and phosphate oxalate) were analyzed in vitro using computed tomography (CT). The mean, central, peripheral, maximum, minimum stone density and stone morphology were determined. At least in vitro, the serial analyses of the mean, minimum, central stone density and stone morphology permitted distinguishing these 6 types of calculi, although 53% of the calcium oxalate dihydrate calculi could not be distinguished from the phosphate oxalate stones.

Chi-Square Distribution↗
PubMed2003

Evaluation of peripheral arterial bypass grafts with multi-detector row CT angiography: comparison with duplex US and digital subtraction angiography.

PURPOSE: To assess the technical feasibility of multi-detector row computed tomographic (CT) angiography in the assessment of peripheral arterial bypass grafts and to evaluate its accuracy and reliability in the detection of graft-related complications, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. MATERIALS AND METHODS: Four-channel multi-detector row CT angiography was performed in 65 consecutive patients with 85 peripheral arterial bypass grafts. Each bypass graft was divided into three segments (proximal anastomosis, course of the graft body, and distal anastomosis), resulting in 255 segments. Two readers evaluated all CT angiograms with regard to image quality and the presence of bypass graft-related abnormalities, including graft stenosis, aneurysmal changes, and arteriovenous fistulas. The results were compared with McNemar test with Bonferroni correction. CT attenuation values were recorded at five different locations from the inflow artery to the outflow artery of the bypass graft. These findings were compared with the findings at duplex ultrasonography (US) in 65 patients and the findings at conventional digital subtraction angiography (DSA) in 27. RESULTS: Image quality was rated as good or excellent in 250 (98%) and in 252 (99%) of 255 bypass segments, respectively. There was excellent agreement both between readers and between CT angiography and duplex US in the detection of graft stenosis, aneurysmal changes, and arteriovenous fistulas (kappa = 0.86-0.99). CT angiography and duplex US were compared with conventional DSA, and there was no statistically significant difference (P >.25) in sensitivity or specificity between CT angiography and duplex US for both readers for detection of hemodynamically significant bypass stenosis or occlusion, aneurysmal changes, or arteriovenous fistulas. Mean CT attenuation values ranged from 232 HU in the inflow artery to 281 HU in the outflow artery of the bypass graft. CONCLUSION: Multi-detector row CT angiography may be an accurate and reliable technique after duplex US in the assessment of peripheral arterial bypass grafts and detection of graft-related complications, including stenosis, aneurysmal changes, and arteriovenous fistulas.

Adult↗
PubMed1994

Simplified nonlinearity correction of oxygen-15-water regional cerebral blood flow images without blood sampling.

UNLABELLED: A noninvasive method, the double-integration method, was developed to estimate regional cerebral blood flow (rCBF) by using 15O-water and PET. It relies on the acquisition of images with a correction of nonlinearity of brain tissue counts and can produce rCBF images on a pixel-by-pixel basis. METHODS: Oxygen-15-water PET studies were performed on five normal human volunteers, and continuous sampling from the radial artery was conducted to generate functional CBF images according to the invasive catheterization method. The method centers on a computer-based program elaborated to calculate an arterial input function with an assumption of the whole brain blood rate of 50 ml/dl/min and consequently does not require arterial catheterization or arterial input function sampled from other studies. RESULTS: The results indicate a good correlation between this method and the invasive method (r > 0.966, p < 0.001). CONCLUSION: This noninvasive method was demonstrated to provide an accurate estimation of rCBF and may simplify the activation studies.

Adult↗
PubMed2007

Ex vivo imaging of chronic total occlusions using forward-looking optical coherence tomography.

BACKGROUND AND OBJECTIVES: Percutaneous coronary interventions (PCI) of chronic total occlusions (CTOs) of arteries are more challenging lesions to treat with angioplasty and stenting than stenotic vessels due primarily to the difficulty in guiding the wire across the lesion. Angiography alone is unable to differentiate between the occluded lumen and the vessel wall and to characterize the content of the occlusion. New technologies to aid in interventional guidance are therefore highly desirable. We sought to evaluate tissue characterization in arterial (CTOs) by imaging ex vivo peripheral arterial samples with optical coherence tomography (OCT). STUDY DESIGN/MATERIALS AND METHODS: Ex vivo arterial samples were obtained from patients undergoing peripheral limb amputation. Samples were imaged in an enface orientation using an OCT system, enabling sequential acquisition of longitudinal images and volumetric reconstruction of cross-sectional views of the occluded arteries. Histology was performed for comparison. RESULTS: OCT imaging reliably differentiated between the occluded lumen and the underlying arterial wall in peripheral CTOs. OCT correctly identified tissue composition within the CTO, such as the presence of collagen and calcium and was also able to identify intraluminal microchannels. CONCLUSIONS: OCT imaging of CTO anatomy and tissue characteristics may potentially lead to substantial improvements in PCI interventions by providing novel guiding capabilities.

Angiography↗
PubMedDate not supplied

Hepatic epithelioid hemangioendothelioma: MR imaging findings.

We describe the sonographic, computed tomography and magnetic resonance imaging findings of two patients with histologically proven hepatic hemangioendothelioma. Both patients presented with multiple liver nodules. Color Doppler ultrasound demonstrated moderate vascularity at the periphery of the nodules, as well as central neovascularity. On enchanced computed tomography images, the lesions showed peripheral enhancement only. On magnetic resonance images, tumor signal was low on T1-weighted and moderately high on T2-weighted images. The distinction between normal liver and tumor was difficult on all sequences. Administration of superparamagnetic iron oxide particles delineated well the tumor by suppressing the signal of the normal liver and better depicted areas of remaining healthy parenchyma.

Adolescent↗
PubMed2002

Enhancing sensitivity to interaural delays at high frequencies by using "transposed stimuli".

It is well-known that thresholds for ongoing interaural temporal disparities (ITDs) at high frequencies are larger than threshold ITDs obtained at low frequencies. These differences could reflect true differences in the binaural mechanisms that mediate performance. Alternatively, as suggested by Colburn and Esquissaud [J. Acoust. Soc. Am. Suppl. 1 59, S23 (1976)], they could reflect differences in the peripheral processing of the stimuli. In order to investigate this issue, threshold ITDs were measured using three types of stimuli: (1) low-frequency pure tones; (2) 100% sinusoidally amplitude-modulated (SAM) high-frequency tones, and (3) special, "transposed" high-frequency stimuli whose envelopes were designed to provide the high-frequency channels with information similar to that available in low-frequency channels. The data and their interpretation can be characterized by two general statements. First, threshold ITDs obtained with the transposed stimuli were generally smaller than those obtained with SAM tones and, at modulation frequencies of 128 and 64 Hz, were equal to or smaller than threshold ITDs obtained with their low-frequency pure-tone counterparts. Second, quantitative analyses revealed that the data could be well accounted for via a model based on normalized interaural correlations computed subsequent to known stages of peripheral auditory processing augmented by low-pass filtering of the envelopes within the high-frequency channels of each ear. The data and the results of the quantitative analyses appear to be consistent with the general ideas comprising Colburn and Esquissaud's hypothesis.

Adult↗
PubMed1978

Cell population kinetics and dose-time relationships for post-irradiation injury of the brachial plexus in man.

Collected data on radiation-induced lesions of the brachial plexus were analyzed on the assumption that this reaction arises from depletion of some unidentified cell population in the irradiated tissues. A multi-probit search program was used to derive best-fitting cell kinetic parameters in a composite multi-target model for cellular radiation lethality and repopulation. From these parameters, a comprehensive iso-effect table, for a wide range of treatment schedules including daily treatment as well as fractionation at shorter and longer intervals, was constructed. The table provides a useful set of tolerance dosage limits for late effects in irradiated peripheral nerve.

Brachial Plexus↗
PubMed1993

Local addition of monosialoganglioside GM1 stimulates peripheral axon regeneration in vivo.

Tubulization repair technique is a useful model to study peripheral nerve regeneration by offering quantifiable parameters to assess the possible effect of exogenously applied substances on nerve repair. In the present study we demonstrated that locally administered GM1 inside a tubular prosthesis at the time of implantation can significantly improve the repair process. The sciatic nerve of 8 male C57BL/6J mice, approximately 3 months old at the time of surgery and divided into two groups of 4 animals each, was transected and the proximal and distal nerve stumps were sutured into a polyethylene tube (PT), 0.76 mm internal diameter (ID), to bridge a nerve gap of 4 mm. The tubes contained 2 microliters of collagen type I (2.4 mg/ml) alone or in combination (1:1 volume ratio) with monosialoganglioside GM1 (10 mg/ml in the final solution). Four additional animals received a PT with 1.14 mm ID filled with 5.5 microliters of collagen/GM1 (at the same ratio and final concentration as above). After 6 weeks the PT with the regenerating nerve cables were processed for total myelinated axon counts with a computer-controlled system. GM1 significantly increased peripheral axon regeneration (3427 +/- 64 myelinated axons for the 0.76-mm PT and 3623 +/- 270 for the 1.14-mm PT, mean +/- SEM) compared to the group receiving collagen alone (2516 +/- 156) and this effect did not depend on tube diameter. This action is possibly due to a stimulating effect of GM1 on neurite outgrowth and sprouting.

Animals↗
PubMed1987

Computerized interactive morphometry in pathology: current instrumentation and methods.

This review is concerned with the current applications of interactive computerized morphometry for diagnostic applications. "Interactive" differs from fully automatic procedures in that the essential function of cell recognition is performed by a trained observer, assisted by a computerized instrument that performs all desirable measurement and processing tasks. This article describes the instrumental needs (video systems, computer, and specialized hardware) and interactive peripherals, in particular, high-resolution touch screens for most common and currently useful video analysis tasks. The authors describe a number of general instrumental procedures with widespread applications (point counting, tracing of contours, graphic standards of size and length, shape analysis, automatic edge detection). Diagnostic procedures are based on the generation of multiple data followed by either multivariate statistical analysis that allows diagnosis of individual cases or hierarchical algorithms. The best current application is the objective study of controversial or difficult cases; there is a possibility that in the future interactive computerized morphometry may become useful for the mass screening of cytologic specimens.

Analog-Digital Conversion↗
PubMed1997

Real-time feedback of body center of gravity for postural training of elderly patients with peripheral neuropathy.

A system that estimates and displays, in real-time, the location of the center of gravity of the human body relative to the feet was developed and then used in a biofeedback training program for improving the postural instability caused by deterioration of the proprioceptive system in elderly patients with significant diabetic sensory neuropathy during perturbations of a support platform. Training sessions were scheduled three times a week for four weeks and consisted of continuous perturbations of the support platform for the standing subject. Postural stability of each subject was evaluated before, during and after training on a weekly basis. After twelve sessions of training, subjects who received visual feedback showed greater reduction in total number of falls and in fall magnitude defined by force in the body suspension cord, and longer delay in time between perturbation and fall than NFB group.

Biofeedback, Psychology↗
PubMed1994

The role of high dose 67-gallium scintigraphy in staging untreated patients with lymphoma.

BACKGROUND: Gallium-67 (67Ga) scintigraphy has been reported to be of limited value in staging lymphoma patients. However, recent technical advances in radionuclide imaging have potentially enhanced the usefulness of this method. AIMS: The purposes of this study were to determine the current: (1) sensitivity and specificity and (2) impact on clinicians' treatment decisions of 67Ga scans performed at a teaching hospital. METHODS: There were 46 newly presenting patients with lymphoma (13 with Hodgkin's disease (HD) and 33 with non-Hodgkin's lymphoma [NHL]). Planar 67Ga scans were performed up to eight days following injection of 300 MBq (8 mCi) with images interpreted by consensus of two blinded observers; sensitivity and specificity were determined on a lesion by lesion basis in comparison to computed tomography (CT) scans, palpation of peripheral lymph nodes and abdominal lymphangiograms (n = 5). The contribution of 67Ga scans to clinicians' treatment decisions was also independently assessed by an experienced oncologist. RESULTS: Gallium-67 scan sensitivity and specificity were 80% and 96% for HD and 59% and 98% for NHL. Initial treatment plans were modified in three individuals (7%; 95% confidence intervals = 3-10%) due to lesions on the 67Ga scan not prospectively detected or considered equivocal on other tests. CONCLUSIONS: Only a small proportion of newly diagnosed lymphoma patients benefit from staging with state of the art planar high dose 67Ga imaging.

Adult↗
PubMed2001

Evaluation of the cable model for electrical stimulation of unmyelinated nerve fibers.

The cable model, used to calculate the membrane potential of an unmyelinated nerve fiber due to electrical stimulation, is reexamined under passive steady-state conditions. The validity of two of the assumptions of the cable model are evaluated, namely that the membrane potential be a function of the axial coordinate only and that the extracellular potential due to the presence of the nerve fiber be negligible. The membrane potential calculated from the passive steady-state cable model is compared with the membrane potential obtained from an analytical three-dimensional (3-D) volume conductor model of a nerve fiber. It is shown that for very small electrode-fiber distances (of only a few fiber radii), both assumptions are violated and the two models give quite different results. Over a wide range of the electrode-fiber distance (about 0.1 mm to 1 cm), both assumptions are fulfilled and the two models give approximately the same results. For very large distances (more than 10 cm, independent of fiber diameter) only the second assumption is satisfied, but a modification of the activating function of the cable model allows to calculate the membrane potential in agreement with the 3-D model.

Electric Stimulation↗
PubMed1994

Fluorine-18 deoxyglucose uptake in sarcoidosis measured with positron emission tomography.

Regional pulmonary glucose metabolism (MRglu; mumol h-1 g-1), extravascular lung density (D(EV); g cm-3) and vascular volume (VB; ml cm-3) were measured in a single midthoracic transaxial slice (approximately 2 cm thick) using position emission tomography (PET) in seven patients with histologically proven sarcoidosis. The measurements were repeated 1-7 months later after steroid therapy (in two cases, no treatment) in order to assess MRglu as an index of inflammation and relate it to routine pulmonary function tests, chest radiography and serum angiotensin converting enzyme (SACE) levels. MRglu was computed from serial lung scans and peripheral venous blood samples for 60 min following an i.v. injection of 18F-2-fluoro-2-deoxy-D-glucose (18FDG). Both MRglu (which was increased in six of seven patients) and elevated SACE levels returned to normal in those patients treated with high-dose steroids. Regional vascular volume was normal in six of seven cases and did not change significantly with therapy. The high tissue density measured in all patients decreased significantly in two of three patients treated with 40 mg prednisolone daily. The abnormal MRglu observed in active sarcoidosis becomes normal pari passu with SACE levels during high-dose steroid therapy. We conclude that MRglu measured with 18FDG and PET may reflect "disease activity" in sarcoidosis in quantitative terms (per gram lung tissue) and in respect of disease distribution.

Adult↗
PubMed1996

Accidental embolization of an intravenous cannula in the upper limb: retrieval following computed tomography localization.

Embolization of small foreign body particles from peripheral veins to the heart or lungs is an uncommon occurrence and, once released into the circulation, localization and retrieval may be difficult. We present a case of accidental separation and embolization of a 28 mm long distal portion of a polytetrafluoroethylene intravenous cannula that was sited in a superficial right wrist vein. The fragment travelled as far as the antecubital fossa prior to the application of a tourniquet. It was then accurately located in the cephalic vein using contiguous axial computed tomography with reconstructions, and was easily retrieved under local anaesthesia. A management approach to this uncommon but potentially serious problem is suggested.

Adult↗
PubMed2004

Iliac vein compression in an asymptomatic patient population.

OBJECTIVE: May-Thurner syndrome is a well-recognized anatomic variant that is associated with the development of symptomatic acute venous thrombosis of the left iliac vein. However, the natural frequency of compression of the left iliac vein and its clinical significance in asymptomatic disease has not been established. Therefore the purpose of this descriptive anatomic study was to determine the incidence of left common iliac vein compression in an asymptomatic population. METHODS: A retrospective analysis of medical records and helical abdominal computed tomography scans was conducted in 50 consecutive patients evaluated in the emergency department because of abdominal pain. Medical records were reviewed for symptoms and risk factors for deep venous thrombosis, and data were collected and reported according to the Joint Society Reporting Standards for acute lower extremity venous thrombosis. All computed tomography was performed with intravenous contrast medium, and 2-mm to 5-mm axial images were obtained. The minor diameter of the common iliac arteries and veins was measured. The technique of transverse image measurement was validated with multiplanar reconstructions and orthogonal diameter measurements in a subset of subjects. Statistical analysis was performed with the Student t test or Spearman rank correlation. RESULTS: Mean age of subjects without symptoms was 40 years (range, 19-85 years), and 60% (n = 30) were female patients. The mean acute lower extremity venous thrombosis risk factor score was 1.16 +/- 0.23 (range, 0-6; maximum possible score, 28). It was surprising that 24% (n = 12) of patients had greater than 50% compression and 66% (n = 33) had greater than 25% compression. Mean compression of the left common iliac vein was 35.5% (range, -5.6%-74.8%). The structure most often compressing the left common iliac vein against the vertebral body was the right common iliac artery (84%). There was no strong correlation between patient age or common iliac artery size and compression of the left common iliac vein. However, women had greater mean compression of the left common iliac vein (women, 41.2% +/- 3.1%; men, 27.0% +/- 3.0%; P =.003). CONCLUSION: Hemodynamically significant left common iliac vein compression is a frequent anatomic variant in asymptomatic individuals. Therefore compression of the left iliac vein may represent a normal anatomic pattern that has thus far been thought of as a pathologic condition.

Adult↗
PubMed1996

Refractive changes during 72-hour exposure to high altitude after refractive surgery.

PURPOSE: The authors prospectively analyzed refractive and pachymetric parameters during exposure to high altitude after radial keratotomy (RK) and photorefractive keratectomy (PRK). METHODS: The authors measured manifest and cycloplegic refraction, keratometry, computed video keratography, and central and peripheral pachymetry in six subjects who have undergone RK (11 eyes), six who have undergone PRK (12 eyes), and nine with myopia (17 eyes) at sea level and on three consecutive days at 14,100 feet. All measurements were repeated 1 week after subjects returned to sea level. RESULTS: Subjects who have undergone RK demonstrated a significant and progressive increase in spherical equivalence (+0.30 +/- 0.50 diopters on day 1 and +1.52 +/- 1.01 diopters on day 3; P < 0.001) and a decrease in keratometry values during exposure to altitude when compared with control subjects with myopia. Healthy subjects and those who have had PRK demonstrated no significant change in refractive error. Pachymetry measurements demonstrated significant peripheral corneal thickening in all three groups (RK, P < 0.004; PRK, P < 0.007; control subjects, P = 0.0006) by day 3 at high altitude. Refraction, keratometry, and pachymetry returned to baseline (P = 1.000) after return to sea level. CONCLUSIONS: Seventy-two-hour exposure to high altitude in subjects who have had RK induces a significant, progressive, and reversible hyperopic shift in refraction with corresponding video keratographic and keratometric changes. The authors hypothesize that the high-altitude hypoxic environment causes increased corneal hydration in the area of the RK incisions, which may lead to central corneal flattening and a hyperopic shift in refractive error. Subjects who have had PRK and those with myopia are not susceptible to this refractive shift. The authors' RK data suggest that the time since surgery and the amount of surgery are related to the degree of hyperopic shift during altitude exposure.

Adult↗
PubMed2003

Assessment of neuroinflammation and microglial activation in Alzheimer's disease with radiolabelled PK11195 and single photon emission computed tomography. A pilot study.

OBJECTIVES: Inflammation contributes to degeneration in Alzheimer's disease (AD), not simply as a secondary phenomenon, but primarily as a significant source of pathology. [(123)I]iodo-PK11195 is a single photon emission computed tomography (SPECT) ligand for the peripheral benzodiazepine receptor, the latter being expressed on microglia (brain resident macrophages) and upregulated under inflammatory circumstances. The objectives were to assess AD inflammation by detecting [(123)I]iodo-PK11195 uptake changes and investigate how uptake values relate with perfusion SPECT and neuropsychological findings. METHODS: Ten AD and 9 control subjects were included. [(123)I]iodo-PK11195 SPECT images were realigned into stereotactic space where binding indices, normalized on cerebellar uptake, were calculated. RESULTS: The mean [(123)I]iodo-PK11195 uptake was increased in AD patients compared with controls in nearly all neocortical regions; however, statistical significance was only reached in the frontal and right mesotemporal regions. Significant correlations were found between regional increased [(123)I]iodo-PK11195 uptake and cognitive deficits. CONCLUSIONS: [(123)I]iodo-PK11195 is a cellular disease activity marker and allows in vivo assessment of microglial inflammation in AD.

Aged↗