A novel 3D multi-scale lineness filter for vessel detection.

The branching pattern and geometry of coronary microvessels are of high interest to understand and model the blood flow distribution and the processes of contrast invasion, ischemic changes and repair in the heart in detail. Analysis is performed on high resolution, 3D volumes of the arterial microvasculature of entire goat hearts, which are acquired with an imaging cryomicrotome. Multi-scale vessel detection is an important step required for a detailed quantitative analysis of the coronary microvasculature. Based on visual inspection, the derived lineness filter shows promising results on real data and digital phantoms, on the way towards accurate computerized reconstructions of entire coronary trees. The novel lineness filter exploits the local first and second order multi-scale derivatives in order to give an intensity-independent response to line centers and to suppress unwanted responses to steep edges.

Model-based cartilage thickness measurement in the submillimeter range.

Current methods of image-based thickness measurement in thin sheet structures utilize second derivative zero crossings to locate the layer boundaries. It is generally acknowledged that the nonzero width of the point spread function (PSF) limits the accuracy of this measurement procedure. We propose a model-based method that strongly reduces PSF-induced bias by incorporating the PSF into the thickness estimation method. We estimated the bias in thickness measurements in simulated thin sheet images as obtained from second derivative zero crossings. To gain insight into the range of sheet thickness where our method is expected to yield improved results, sheet thickness was varied between 0.15 and 1.2 mm with an assumed PSF as present in the high-resolution modes of current computed tomography (CT) scanners [full width at half maximum (FWHM) 0.5-0.8 mm]. Our model-based method was evaluated in practice by measuring layer thickness from CT images of a phantom mimicking two parallel cartilage layers in an arthrography procedure. CT arthrography images of cadaver wrists were also evaluated, and thickness estimates were compared to those obtained from high-resolution anatomical sections that served as a reference. The thickness estimates from the simulated images reveal that the method based on second derivative zero crossings shows considerable bias for layers in the submillimeter range. This bias is negligible for sheet thickness larger than 1 mm, where the size of the sheet is more than twice the FWHM of the PSF but can be as large as 0.2 mm for a 0.5 mm sheet. The results of the phantom experiments show that the bias is effectively reduced by our method. The deviations from the true thickness, due to random fluctuations induced by quantum noise in the CT images, are of the order of 3% for a standard wrist imaging protocol. In the wrist the submillimeter thickness estimates from the CT arthrography images correspond within 10% to those estimated from the anatomical sections. We present a method that yields virtually unbiased thickness estimates of cartilage layers in the submillimeter range. The good agreement of thickness estimates from CT images with estimates from anatomical sections is promising for clinical application of the method in cartilage integrity staging of the wrist and the ankle.

Visualisation of intramural coronary vasculature by an imaging cryomicrotome suggests compartmentalisation of myocardial perfusion areas.

A technique is presented for the 3D visualisation of the coronary arterial tree using an imaging cryomicrotome. After the coronary circulation of the excised heart was filled with a fluorescent plastic, the heart was frozen and mounted in the cryomicrotome. The heart was then sliced serially, with a slice thickness of 40 microm, and digital images were taken from each cutting plane of the remaining bulk material using appropriate excitation and emission filters. Using maximum intensity projections over a series of images in the cutting plane and perpendicular plane, the structural organisation of intramural vessels was visualised in the present study. The branching end in the smallest visible vessels, which define tissue areas that are well delineated from each other by 1-2 mm wide bands populated only by vessels less than 40 microm in diameter. The technique presented here allows further quantification in the future of the 3D structure of the coronary arterial tree by image analysis techniques.

Stroke in ovarian hyperstimulation syndrome in early pregnancy treated with intra-arterial rt-PA.

Ovarian hyperstimulation syndrome (OHSS) caused by fertility medications can predispose women to thrombosis. The authors present a case of a previously healthy woman who underwent in vitro fertilization and experienced a middle cerebral artery thrombosis that was subsequently lysed with intra-arterial recombinant tissue plasminogen activator (rt-PA). To the authors' knowledge, this is the first reported case of successful use of rt-PA to lyse a cerebral arterial thrombus resulting from severe OHSS. The patient made a near complete neurologic recovery and delivered a healthy infant at term, illustrating that intra-arterial thrombolysis can be used with relative safety even in very early pregnancy.

In vitro prediction of carcinogenicity using a bovine papillomavirus DNA--carrying C3H/10T 1/2 cell line (T1). II: Results from the testing of 100 chemicals.

A new in vitro test for identifying carcinogens is evaluated against a testing database of 100 chemicals including the following groups: steroids, antineoplastics, PCBs, dioxins, alkyl halides, aromatic amines, nitrogen heterocycles, polyaromatic hydrocarbons, mustards, and benzodioxoles. The assay uses focus formation in a stable, BPV-1-DNA-carrying C3H/10T 1/2 mouse embryo fibroblast cell line (T1), which does not require transfection, infection with virus, or isolation of primary cells from animals. For this group of chemicals, the T1 assay correctly predicted the rodent carcinogenicity or noncarcinogenicity of 77% of the chemicals for which carcinogenicity is reported. Based on published data the bacterial mutagenicity assay would have correctly predicted carcinogenicity or noncarcinogenicity of 53% of the chemicals. The Syrian hamster embryo test would have correctly predicted carcinogenicity or noncarcinogenicity of 61% of the chemicals. We also demonstrate dose--response relationships for two of the chemicals. We report the responses of T1 cells to the group of chemicals used in the International Life Sciences Institute's program for screening of alternative methods of predicting carcinogenicity.

Intracranial hemorrhage after stenting and angioplasty of extracranial carotid stenosis.

BACKGROUND AND PURPOSE: The transluminal angioplasty and stenting procedure has been recently advocated as a potential alternative to surgical endarterectomy for the treatment of severe extracranial carotid stenosis. This study assesses the incidence and significance of intracranial hemorrhage occurring after this procedure. METHODS: We retrospectively reviewed 104 carotid arteries (96 internal, two external, and six common) in 90 patients (63 male; mean age, 69.4 years; range, 48-88 years) who underwent primary stenting and angioplasty by use of Wallstents (103/104) at three centers between January 1996 and January 1999. Seventy-five (83%) patients were referred by neurosurgery departments. Seventy-one (68%) arteries were symptomatic; the mean stenosis percentage was 85% (range, 40-99%). RESULTS: Four intraparenchymal hemorrhages occurred, representing 4.4% of patients and 3.8% of vessels, after angioplasty and stent placement. The mean preoperative stenosis percentage was 95% (range, 90-99%). One hemorrhage occurred immediately after stent placement, whereas the three other hemorrhages occurred in a delayed fashion (mean, 2.8 days). The mean hematoma size was 4.8 cm (range, 2-8 cm). Three patients had associated subarachnoid or intraventricular bleeding; the fourth had associated subdural hemorrhage. Three hemorrhages were fatal; the fourth experienced two seizures only. No acute neurologic symptoms were present prior to hemorrhages, and there was no postprocedural hypertension in these patients. All had been receiving antiplatelet agents as well as intraprocedural IV heparin. CONCLUSION: Intracranial hemorrhage can occur after carotid angioplasty and stenting. We speculate that this represents cerebral hyperperfusion injury. The 3.8% incidence of cerebral hemorrhage observed is approximately sixfold greater than that reported post endarterectomy (0.6%) (95% CI, 0.2-8.7%). This is not statistically significant in this small study group. This trend may reflect patient selection, different anticoagulation protocols, and/or study population size. Additional data are needed to determine the safety and efficiency of carotid stenting as a treatment for carotid stenosis.

In vitro determination of carcinogenicity of sixty-four compounds using a bovine papillomavirus DNA-carrying C3H/10T(1/2) cell line.

A new in vitro test for predicting rodent carcinogenicity is evaluated against a testing database of 64 chemicals including both genotoxic and nongenotoxic carcinogens and carcinogens that normally require addition of an S-9 microsomal fraction for detection in the bacterial mutagenicity assay. The assay uses focus formation in a stable, bovine papillomavirus type 1 (BPV-1) DNA carrying C3H/10T(1/2) mouse embryo fibroblast cell line (T1) that does not require transfection, infection with virus, isolation of primary cells from animals, or addition of a microsomal fraction. Of a total database of 64 compounds, 92% of the carcinogens, promoters, or noncarcinogens were correctly predicted. Based on previously reported results, the test of bacterial mutagenicity would have correctly predicted 58% of carcinogens, promoters or noncarcinogens and the Syrian hamster embryo test would have correctly predicted 87% of carcinogens, promoters, or noncarcinogens of this database. Of carcinogens that normally require addition of an S-9 fraction, T1 cells correctly predicted rodent carcinogenicity of polyaromatic hydrocarbons, aflatoxins, azo-compounds, nitrosamines, and hydrazine without the addition of an S-9 fraction. Of nongenotoxic carcinogens, T1 cells correctly predicted diethylstilbestroel, diethylhexylphthalate, acetamides, alkyl halides, ethyl carbamate, and phorbol ester tumour promoters.

Reversible cerebral, hepatic and renal lesions in severe pre-eclampsia.

Several authors have reported the appearance of reversible hypoattenuated cerebral lesions, representing ischemia, in computed tomography scans of patients with severe pre-eclampsia. Hepatic hemorrhage and sometimes rupture have also been reported in this setting, but these problems have apparently never occurred in a patient with reversible ischemia. The authors describe a 34-year-old patient with severe pre-eclampsia in whom reversible cerebral ischemia developed in combination with hepatic and renal hematomas, which subsequently partially resolved.

Development of an electronic prescription processing option: an aid for general practice.

An interactive computer-supported prescription processing system has been developed as an add-on to existing general practitioner information systems. The aim of the system is to improve the clarity, efficiency and economy of drug treatment choices and prescription writing. It enables the doctor to choose the best treatment from the system's formulary according to the patient's complaint, symptom or diagnosis. The selections are based on complaints and diagnoses from the International classification of primary care (ICPC). A prescription is printed and the potential exists for individualized patient instruction leaflets to be printed. Furthermore, the system may prove useful for retrospective and prospective statistical and epidemiological studies. This implies continuous adaptation, which is also necessary to keep the system updated. As well as an aid in daily general practice, the system is also designed to serve the needs of graduate and postgraduate training programmes.

Diagnostic accuracy of preoperative CT scanning of pituitary prolactinomas.

Between 1980 and 1985, 102 patients (84 women and 18 men) who had coronal CT scans of the sella turcica for suspected prolactin adenoma underwent transsphenoidal exploration. The CT examinations were performed with a fourth-generation EMI scanner (CT 7070), and reports of the preoperative CT examinations were compared with the findings at transsphenoidal exploration. The same neurosurgeon performed all the operations. In 97 patients distinct adenomas were found at surgery, among which were 36 macroadenomas (diameter larger than 10 mm) and 62 microadenomas (one patient had two coexisting microadenomas). All macroadenomas were identified correctly on the preoperative CT scans. Preoperative CT scans correctly localized 58 microadenomas in 57 of 62 patients, for a sensitivity rate of 91.9%; this included correct localization in four patients with recurrent microprolactinomas and in the one patient with two coexisting adenomas. Three patients in whom the adenomas were found in a location other than that reported on the preoperative CT scan were considered to have false-negative scans for the purpose of statistical calculations; two other false negatives occurred in patients whose scans had been interpreted as entirely normal and who were subsequently found to have adenomas at operation. Four patients had negative surgical explorations and the preoperative CT scan was correct in one, for a specificity of 25%. The overall accuracy rate was 92.1% for the entire group of patients and 87.7% for the subgroup of microadenomas. In our experience, coronal CT scanning has high diagnostic accuracy in patients with pituitary prolactinomas.

Diagnostic accuracy of preoperative CT scanning of pituitary somatotroph adenomas.

Between 1980 and 1986, 58 patients (23 women and 35 men) had coronal CT scans of the sella turcica for suspected growth hormone-secreting adenoma and underwent transsphenoidal exploration. The CT examinations were performed with a fourth-generation EMI scanner (CT 7070), and reports of the preoperative CT were compared with the findings at transsphenoidal exploration. The same neurosurgeon performed all the operations. In three patients arthritic changes in the neck caused difficulties in positioning, which made it impossible to obtain adequate coronal CT scans. These nondiagnostic examinations are excluded from the statistical calculations. In all 55 patients with scans that were able to be evaluated, distinct adenomas were found at surgery. Among these were 39 macroadenomas (diameter larger than 10 mm) and 16 microadenomas. Three macroadenomas and two microadenomas caused combined hypersecretion of growth hormone and prolactin. All macroadenomas were localized correctly on the preoperative CT scans (sensitivity 100%), but in two cases there was a discrepancy in size of more than 5 mm compared with the operative findings. Preoperative CT scans correctly localized 13 of 16 microadenomas, for a sensitivity rate of 81.2%. Two patients with negative scans and one patient in whom the adenoma was found in a location other than that reported on the preoperative CT scan were considered to have negative scans for the purpose of statistical calculations. If both correct localization and size estimation within 2 mm of that found at surgery are considered, the accuracy rate was 90.9% for the entire group of patients, 94.9% for those with macroadenomas, and 81.2% for microadenomas.

The diagnostic accuracy of preoperative CT scanning in the evaluation of pituitary ACTH-secreting adenomas.

Between 1980 and 1985, 35 patients (26 women and nine men) who had coronal CT scans of the sella turcica for suspected ACTH-secreting pituitary adenoma underwent transsphenoidal exploration. The CT examinations were performed with a fourth-generation EMI scanner (CT 7070). The reports of the preoperative CT examinations were compared with the findings at transsphenoidal exploration; in cases with negative CT scans, the decision to operate was based on biochemical evidence of Cushing's disease. In 27 patients, distinct adenomas were found at surgery; in the eight others, total hypophysectomy (four cases) or resection of the central core of the pituitary gland (four cases) was performed. Three patients had macroadenomas, all of which had been identified correctly on preoperative CT scan. Among the 24 microadenomas (less than 10 mm diameter), 14 had been correctly identified on preoperative CT scan while 10 were found in patients with negative scans. The CT examinations in these 35 patients showed probable adenomas in 20 cases, of which 17 (85%) were confirmed at surgery. In the other three cases (15%), adenomas were not found. Among the 15 patients with negative CT scans, 10 (66.6%) had distinct adenomas found at surgery. Coronal CT scans for ACTH-secreting adenomas had a sensitivity of 63%, a specificity of 62.5%, and an overall accuracy rate of 62.8%. Thus, in our experience, CT scanning with current state-of-the-art equipment has poor diagnostic accuracy in Cushing's disease. The possible reasons for this are that most of the adenomas in this series were microadenomas less than 6 mm in diameter, and that ACTH microadenomas probably show almost the same degree of enhancement with contrast medium as the surrounding normal pituitary tissue.

Intrasellar germinoma associated with hyperprolactinemia.

We report two young adult patients with hyperprolactinemia and neuroendocrine deficits due to predominantly intrasellar germinomas. In both cases the diagnosis of germinoma was confirmed histologically after transsphenoidal surgery. This very rare type of tumor may be intrasellar and it may mimic prolactinoma or craniopharyngioma. Dynamic testing of pituitary function and computed tomography scanning are of value in the early detection of this malignant but radiocurable lesion.

Computed tomography in the evaluation of plexopathies and proximal neuropathies.

We describe nine patients with plexopathies or proximal mononeuropathies due to mass lesions. In four, computed tomography (CT) was the only radiological technique to show the cause of the neuropathy. In five patients, CT either unequivocally confirmed the presence of an abnormality or was superior to other imaging techniques in showing its full anatomical extent. CT scanning is a valuable aid in the assessment of lesions of the peripheral nervous system, particularly plexopathies and mononeuropathies caused by retroperitoneal, pelvic or superior pulmonary sulcus tumors.

Progressive multifocal leukoencephalopathy.

The radionuclide, radiographic and pathologic findings in a patient with progressive multifocal leukoencephalopathy were correlated. Radionuclide imaging demonstrated the largest two of the many lesions observed at pathology. On repeated studies, one of the lesions developed a "doughnut" sign due to central necrosis. Cerebral angiography disclosed only one lesion which was initially suggestive of tumor encasement, but four weeks later, this deteriorated into an avascular zone. There were no characteristic features of the lesions demonstrated by radionuclide imaging and cerebral angiography that could be specifically attributed to progressive multifocal leukoencephalopathy.