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4 result(s) for "Cohnen, Mathias"
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Comparison of whole-body 64-slice multidetector computed tomography and conventional radiography in staging of multiple myeloma
This study compares the sensitivity of whole-body multidetector CT (MDCT) and conventional radiography (CR) in the staging of multiple myeloma (MM). Twenty-nine patients with MM underwent a staging examination both by MDCT and CR. CT examination was performed with a collimation of 64×0.6 mm, a tube potential of 100 kVp, an effective tube current-time product of 100 mAs and automatic dose modulation as low-dose protocol. Number, size and diagnostic confidence of osteolytic lesions were determined and compared. The effective dose of MDCT and CR was assessed. Using MDCT, the detection of osteolysis was increased seven-fold concerning the spine. Ninety-seven lesions in 18 patients were detected exclusively by MDCT. The detection rate concerning the spine, pelvic skeleton and thoracic cage was significantly higher (p≤0.001), and diagnostic confidence was increased by MDCT (p<0.02) compared to CR. Therapy was changed after MDCT in 18.2% of the patients with a clinical suspicion of progressive disease. The estimated effective dose of MDCT (4.8 mSv) and CR (1.7 mSv) was comparable. In conclusion, MDCT has a significantly higher sensitivity and reliability in the detection of osteolysis than CR and can be recommended as standard imaging method in the staging of MM.
Detection of changed regional cerebral blood flow in mild cognitive impairment and early Alzheimer's dementia by perfusion-weighted magnetic resonance imaging
The utility of perfusion-weighted magnetic resonance imaging (PW-MRI) for detecting changes in regional cerebral blood flow (rCBF) in patients with mild cognitive impairment (MCI) and early Alzheimer's disease (AD) was evaluated. Thirteen cognitively normal (CN) elderly subjects, 35 mostly amnestic MCI subjects and 20 subjects with mild probable AD were enrolled. During i.v. injection of gadopentetate dimeglumine, a dynamic T2*-weighted single-shot EPI sequence was conducted using a 1.5-T scanner. Frontobasal (FROB), temporoparietal (TPAR), mesiotemporal (MTMP), anterior and posterior cingular (ACING, PCING), amygdala (AMYG), thalamus and cerebellar brain regions were studied. rCBF was computed from regional cerebral blood volume and arterial input function and normalised to white matter. Images were analysed by manually placed regions of interest using anatomical coregistration. Significant decreases of rCBF were detected in MCI vs. CN in MTMP (−23%), AMYG (−20%) and ACING (−15%) with no further decline in mild AD. In PCING hypoperfusion (−10%) was confined to AD. These hypoperfusional changes are a possible correlate of localised impairment of CNS function. In FROB no perfusion changes were observed between diagnostic groups, but hyperperfusion was observed in mild dementia stages, possibly reflecting functional compensatory mechanisms. These data suggest that PW-MRI detects specific changes in rCBF not only in AD, but also in amnestic MCI, a disorder suggested to largely represent a pre-dementia stage of AD. This method may thus be useful in both research and clinical applications to detect early functional brain changes in the pathogenesis of dementias.
Effective doses in standard protocols for multi-slice CT scanning
The purpose of this study was to assess the radiation exposure of patients in several standard protocols in multi-slice CT (MSCT). Scanning protocols for neck, chest, abdomen, and spine were examined on a Somatom Plus 4 Volume Zoom MSCT (Siemens, Erlangen, Germany) with changing slice collimation (4x1, 4x2.5, and 4x5 mm), and pitch factors (1, 1.5, and 2). Effective doses were calculated from LiF-TLD measurements at several organ sites using an Alderson-Rando phantom and compared with calculations using the weighted CTDI. Effective dose for MSCT of the neck was 2.8 mSv. For different protocols for MSCT of the chest, 7.5-12.9 mSv were found. In abdominal MSCT protocols, effective dose varied between 12.4 and 16.1 mSv. The MSCT of the spine may lead to 12 mSv. An excellent correlation between the effective dose as determined by LiF-TLD and the calculated effective dose using the weighted CTDI could be demonstrated; however, a difference of up to 30% (mean 14.3%) was noted. Standard protocols for MSCT as measured in this study showed effective doses of up to16 mSv. Phantom measurement data show a good correlation to estimations using the weighted CTDI.
Minimally Invasive Therapy of Pseudoaneurysms of the Trunk: Application of Thrombin
Thrombin injection has been proven to be successful in postcatheterization pseudoaneurysms. However, there are only a few reports on the treatment of pseudoaneurysms of the trunk. We report our first experiences using a percutaneous as well as an endovascular access. Eight iatrogenic pseudoaneurysms of the trunk (aorta, n =  4; pulmonary artery, n =  1; gastroduodenal artery, n =  1; left gastric artery, n =  1, renal artery, n =  1) were treated either percutaneously using CT guidance ( n =  3) or via an endovascular access ( n =  5). Noninvasive control angiograms were performed at day 1 and weeks 1 and 3 by either CT or MR angiography. The total volume of the pseudoaneurysms was 31.2 ± 23.1 ml on average, with a mean volume of the perfused aneurysmal lumen of 12.9 ± 7.2 ml. The maximum diameter was 4.1 ± 1.39 cm on average. In each case, the aneurysmal neck was not wider than 2 mm. One pseudoaneurysm occluded spontaneously following selective catheterization. The remaining pseudoaneurysms were successfully treated by injection of 765 ± 438.1 IU thrombin. In one individual, a nontarget embolization occurred, as well as an intervention-associated rupture of a pseudoaneurysm. High-grade stenoses of the donor artery were found in a different case. Only once was the endoluminal access converted to a percutaneous one. Thrombin injection might be a future first-line treatment of vascular lesions such as pseudoaneurysms of the trunk. In our experience both percutanous and endoluminal access are technically feasible and safe. However, further experiences are mandatory, especially concerning the question of dosage and long-term results.