Biomedical subjects
Publications and source records attributed to N Abolmaali.
Odors influence human behavior. The perception of so-called pheromones is frequently mentioned in the context of a functional vomeronasal organ. Vomeronasal ducts can be detected in approximately half of the population. Its functionality, still a matter of debate, seems to be unlikely, at least after birth. It is easily conceivable that pheromone-induced changes in behavior are mediated through receptors in the human olfactory epithelium.
With the introduction of multislice CT extensive volumetric data sets can be quickly acquired in high spatial resolution. The high spatial resolution reduces partial volume effects and enables multiplanar reconstructions. Regarding the colorectum this means that the colon can be assessed if the colon is sufficiently cleaned and distended, and that transmural infiltration of colorectal carcinoma and liver metastases can be better detected. T-staging of colon cancer is less important than T-staging of rectal cancer. Based on the higher contrast MRI is superior to CT in T-staging of rectal cancer and in the differentiation between scarring tissue and recurrence of carcinoma.
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PURPOSE: To visualise the vessel wall of the descending thoracic aorta using magnetic resonance imaging. To evaluate the diagnostic potential of tailored T1-weighted sequences with contrast enhancement to assess systemic atherosclerotic disease. METHODS: This study was performed on a clinical 1.5 Tesla scanner using a gradient strength of 30 mT/m and the phased array spine coil. A cadaver was examined to optimise a magnetic resonance imaging (MRI) protocol to evaluate atherosclerotic aortic wall disease. The acquired MR images were compared to gross specimens and histology. Subsequently seven patients who had undergone transesophageal ultrasound (TEU) with detailed assessment of the descending thoracic aorta were examined with MRI. The optimised protocol included untriggered and fat suppressed T2-weighted turbo spin echo sequences and ECG-triggered and fat suppressed T1-weighted spin echo sequences before and after iv administration of Gd-DTPA. Findings of the MR images were compared to the results of TEU. Contrast enhancement measurements were performed in normal and thickened vessel wall segments. RESULTS: For the cadaver study a good correlation of the degree of vessel wall thickening and the extent of plaque imaged with the applied MR protocol was found. Tissue characterisation was limited due to post mortem changes. In vivo ECG-triggered T1-weighted images showed good correlation to TEU in terms of vessel wall thickness and plaque extension as verified by means of consensus reading. Differentiation of the plaque components fat, calcium and fibrous tissue was possible. In thickened aortic wall segments and fibrous caps a mean contrast enhancement of 50.4 % +/- 23.5 % was measurable while normal wall segments showed an enhancement of 6.7 % +/- 3.1 %. The difference of contrast enhancement was highly significant (p < 0.0001). CONCLUSION: Using fat suppressed T1-weighted sequences with contrast enhancement the extent of atherosclerotic vessel wall changes can be demonstrated. The suggested MR protocol contains a high potential for diagnosis and follow-up of therapy of atherosclerotic disease of the descending thoracic aorta.
AIM: In MR perfusion measurements of contrast uptaking lesions, time intensity curves are hampered by T 1 shortening as well as by the change of T 2 * due to interstitial contrast material (CM). Using double echo sequences, the influence of T 1 can be mathematically eliminated. For correction of the T 2 * influence an empirical algorithm using time-intensity-curves exclusively measured in the suspected lesion is proposed. METHODS: The interstitial CM concentration is assumed to be proportional to the change of the intensity for T E = 0 or to the change of the relaxation rate DeltaR 1 respectively. The intravascular CM concentration is estimated from DeltaR 2 *. It is adjusted to zero for a time point sufficiently late after the bolus injection by subtraction of the interstitial concentration. This method was applied to double echo FLASH measurements on 15 pharyngeal tumors. RESULTS: The proposed correction transforms the time dependence of the estimated intravascular CM concentration into a plausible course. CONCLUSION: Double echo perfusion measurements can be corrected for the interstitial CM induced T 2 * shortening without additional measurements with proneness to errors. This does not necessarily improve the diagnostic value, since possibly "implied multivariate aspects" of uncorrected parameters (here: contrast uptake of the lesion is related to tumor neoangiogenesis as well) are eliminated.
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Most frequent complications in patients with liver cirrhosis are due to portal hypertension. Beside ascites circumvent vessels formate with vasodilatation. Due to counterregulation a secondary hyperaldosteronism develops with release of vasocontrictive agents. If conservative and endoscopic methods fail, indication for building a portosystemic shunt is given. The TIPSS procedure is less invasive than the surgical method of Warren-Shunt, so the radiological intervention has replaced surgery. Reducing the portal pressure by the shunt, the clinical complications change for the better. Still problems are defined as hepatic encephalopathy and right ventricular heart failure. Regular follow up investigations have to be performed to detect complications in the shunt. Using regular clinical and radiological check up TIPSS is of clinical benefit with good long term results.
PURPOSE: To evaluate the effectiveness of diagnostic and interventional radiological techniques for neoplastic lesions of the temporomandibular joint (TMJ). MATERIAL AND METHODS: Modern diagnosis of the TMJ is based on the clinical use of conventional X-ray techniques, computed tomography (CT), magnetic resonance imaging (MRI) and interventional techniques like biopsies, vascular occlusion and ablation. RESULTS: Conventional X-ray still forms the basic diagnostic procedure applied in open and closed mouth position. CT improves the diagnostic information and serves as the standard diagnostical instrument for cartaliganeous or osseous neoplastic lesions. MRI evaluates soft tissue infiltration in multiplanar techniques and high spatial resolution. Interventional vascular and ablative techniques improve the treatment of neoplastic disorders. CONCLUSION: Radiological diagnostic procedures are essentials for the diagnosis and intervention of neoplastic lesions of the temporomandibular joint.
BACKGROUND: Kallmann's syndrome (KS) was first mentioned in 1944 as an association of anosmia and hypogonadotropic hypogonadism. Causes are multiple genetic defects the most common of which is the x-linked KS appearing mostly in men. However, autosomal dominant and autosomal recessive forms have also been described. PATIENT: We present a case of KS with normosmia (male, 39 years of age). All symptoms of hypogonadotropic hypogonadism were present. RESULTS: Psychophysical olfactory testing revealed left-sided anosmia with right-sided normosmia which was confirmed by electrophysiological measures of olfactory function. Magnetic resonance imaging indicated aplasia of the left olfactory tract and bulb, whereas the right-sided structures appeared to be normal. CONCLUSIONS: As indicated in this case with lateralized anosmia and contralateral normosmia, overall olfactory function strongly depends on the "best" nostril. Therefore, in many clinical situations, lateralized olfactory testing appears to be extremely important.
OBJECTIVE: To evaluate the performance of 4 different visualization techniques for multislice CT datasets from the coronary arteries in comparison to coronary angiography. MATERIAL AND METHODS: 42 patients were examined prospectively using both multislice CT and angiocardiography. All CT scans were performed at collimation 4 x 1 mm, pitch 1.5 and a rotation time of 500 msec. Using retrospective ecg-gating, image reconstruction parameters were 1.25 mm slice thickness, 0.5 mm increment and kernel B30. Each patient's CT dataset subsequently was explored using axial, multiplanar, three-dimensional, and virtual endoscopic visualization modes. RESULTS: Axial scans showed the highest sensitivity in the evaluation of stenoses (66.7%), followed by virtual endoscopy (55.9%), multiplanar (48.6%), and three-dimensional reformations (33.3%). With regard to the detection of atherosclerotic plaques, axial scans (71.2%), three-dimensional reformations (70.1%), and virtual endoscopy (69.1%) displayed comparable sensitivities, whereas multiplanar reformations showed distinctly lower results (55.6%). On combining the techniques a sensitivity of 74.2% for the detection of atherosclerotic plaques, of 72.0% for the identification of high-grade stenoses, respectively, was obtained. The specificity of all four visualization modes amounted to 91.9% and above. Best results have been obtained within the RIVA (sensitivity 85.2%). CONCLUSION: For the detection of atheromatous changes CT angiocardiography does not achieve a sensitivity as high as angiocardiography and is restricted to the three major branches. At heart rates below 60 bpm axial scans showed the best correlation in the quantification and classification of atherosclerotic plaques.
An optimized examination protocol for the MRI evaluation of the temporomandibular joint (TMJ) is presented. The MRI protocol is based on an optimized coil technology, sequence design, and a programmed examination protocol for diagnostics of the TMJ. Depending on the clinical findings, MRI provides an all-in-one diagnostic protocol for the diagnosis of degenerative, inflammatory and tumorous lesions of the TMJ. MRI using an optimized examination protocol should become the primary examination protocol for diseases of the TMJ.
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PURPOSE: The value of CT-angiography (CT-A) for the visualization of intracranial aneurysms was more closely defined by comparison with digital subtraction angiography (DSA). METHODS: Over a period of 18 months a total of 106 patients in whom a subarachnoidal hemorrhage had been detected on native CT were examined in parallel by spiral CT and DSA. CT-angiography was performed under standardized parameters and included processing with 3D surface reconstructions. RESULTS: In 64 patients (60.4%) a total of 72 aneurysms were detected. In four cases (6.2%) there were two and in two cases (3.1%) even three aneurysms. The findings of DSA and CTA agreed in 98 cases (92.5%). In four patients (3.8%) a false negative result was obtained in CTA and the initial DSA. CONCLUSIONS: Digital subtraction angiography must still be considered as the gold standard in the diagnosis of cerebral aneurysms. On account of its excellent spatial delineation of aneurysms and possibilities for exact measurements, CT-angiography represents a valuable, supplementary method--in some cases also an alternative method--to digital subtraction angiography.
Ultrasonography is the predominating method for the diagnosis of altered superficial lymph nodes. According to well defined criteria, the differentiation between benign and malignant nodal disease is possible with a high accuracy. The major concern of diagnosis is the characterization of enlarged lymph nodes, the staging and the long-time control of patients with tumors of the head and the neck and of patients with melanomas. Exemplary typical appearances of altered lymph nodes will be explained. Beside size and shape of the node, it is important to have a close look to its internal structure. The central echogenic hilus, the nodal cortex and their relation has to be noted and excentric hypoechoic structures must be described. According to the literature and to our own experience, it will be shown how reliable the commonly used diagnostic systems are.