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Papers by Christian Vollmar
Journal of Nuclear Medicine
Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has d... more Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has delivered promising accuracy in the detection and validation of coronary lesions. Myocardial perfusion imaging (MPI) using SPECT is an established method for noninvasively assessing the functional significance of coronary stenoses and delivers valuable information for risk stratification. This retrospective analysis compared the accuracies of MDCT angiography and MPI in the detection of hemodynamically relevant lesions of the coronary arteries. Methods: Twenty-five patients with suspected or known coronary artery disease were studied. Electrocardiographically gated MPI and 16-MDCT angiography were performed. Myocardial perfusion images were analyzed by 2 experienced observers, and reversible and fixed perfusion defects were detected and allocated to their corresponding coronary vessels. For the evaluation of MDCT angiography, image quality was determined, and lesions Ն 50% and luminal narrowing Ͻ 50% were visually assessed and characterized by 2 independent observers unaware of the results of MPI. Results: Ninety-nine coronary vessels were analyzed, and the quality of MDCT angiography images was assessed for 330 coronary segments. Coronary artery diameter was interpretable for 231 (70%) of 330 segments, whereas in 99 (30%) of 330 segments, vessel diameter could not be evaluated because of heavy calcifications, blurring, motion artifacts, or intracoronary stents. MDCT angiography detected stenoses Ն 50% in 15 of 100 coronary arteries. Eight (53%) of 15 stenoses Ն 50% showed reversible or fixed perfusion defects in the corresponding myocardial areas on MPI. Sensitivity, specificity, and negative and positive predictive values were 100%, 87%, 100%, and 29%, respectively, for the ability of MDCT angiography to detect reversible perfusion de-fects in the corresponding myocardial areas. Conclusion: MDCT angiography detected myocardial ischemia, as defined by reversible perfusion defects on MPI, with a positive predictive value of 29% in a nonselected study cohort. Compared with MPI alone, MDCT angiography added important morphologic information, but MPI remains mandatory for evaluating the functional relevance of coronary artery lesions.
JAMA neurology, Jan 19, 2015
A 25-year-old right-handed physical education student was buried by an avalanche during a ski tou... more A 25-year-old right-handed physical education student was buried by an avalanche during a ski tour, resulting in 15 minutes of hypoxia. He developed posthypoxic intention myoclonus with involuntary myoclonic jerks of the mouth induced by talking and of both legs by walking. Both arms were unaffected. Weeks later when the patient was trying to solve sudoku puzzles, which he imagined in a 3-dimensional manner, he developed clonic seizures of the left arm associated with a right centroparietal seizure pattern on electroencephalography ( ; eFigure in the Supplement). The unilateral clonic seizures stopped immediately when the sudoku puzzle was discontinued. To solve a sudoku puzzle, every digit from 1 to 9 must appear in each of the 9 vertical columns, in each of the 9 horizontal rows, and in each of the 9 boxes.
Neuroradiology, 2015
Basilar artery (BA) perforator aneurysms may lead to severe subarachnoid hemorrhage (SAH). The ac... more Basilar artery (BA) perforator aneurysms may lead to severe subarachnoid hemorrhage (SAH). The acute management is uncertain. The anatomic approach is challenging both for coiling and clipping, and flow diverter stenting may be dangerous due to the required antiplatelet therapy. We report on our experiences in eight patients. We retrospectively analyzed eight patients with ruptured BA perforator aneurysm, including clinical characteristics, imaging data, treatment regimen, clinical course, and long-term outcome. Patients presented with major SAH and World Federation of Neurosurgical Societies (WFNS) scores of I in three, II in two, and V in three cases. In four patients, the aneurysm was detected in the initial angiography, in four only in follow-up angiography. Five patients were treated conservatively and three patients had endovascular therapy. In the conservative group, the aneurysm spontaneously thrombosed in three cases. One patient suffered from a re-SAH and stayed permanently dependent due to an associated perforator stroke (modified Rankin Scale (mRS) 5). The remaining four patients recovered well (mRS 0 and 1 in two cases, each) including three patients also exhibiting perforator strokes. Regarding the endovascular group, one parent vessel was an angioma feeder and embolized with Onyx. The second aneurysm spontaneously thrombosed periinterventionally. The third patient underwent coiling. Two parent vessels were occluded postinterventionally, resulting in perforator strokes. Final mRS scores were 0, 2, and 2, respectively. Conservative management of ruptured BA aneurysms might be a first-line treatment option with common spontaneous aneurysm occlusion, low rate of re-SAH, and promising clinical outcome.
Klinische Neurophysiologie, 2012
Journal of Nuclear Medicine
A wide range of techniques for registration of medical images has been devised in recent years. T... more A wide range of techniques for registration of medical images has been devised in recent years. The aim of this study is to quantify the overall spatial registration error of 3 different methods for image registration: interactive matching, surface matching, and uniformity index matching as described by Woods. Methods: MRI and ethylcysteinate dimer-SPECT images of the brain were registered for 15 patients. The matching error was assessed by determining intra-and interobserver variability of registrations. Quantification of the registration error was based on the mean spatial distance of 5000 voxels between 2 image positions. The mean position after repeated registrations in each patient was used as the gold standard. To evaluate the coherence of the 3 different registration methods, intermethod variability was determined. Results: Interactive matching showed an intraobserver/ interobserver variability of 1.5 Ϯ 0.3 mm/1.6 Ϯ 0.3 mm (mean Ϯ SD). The time demand for this method was 11 Ϯ 5 min. Surface matching revealed a variability of 2.6 Ϯ 1.1 mm/3.8 Ϯ 1.0 mm and a time demand of 26 Ϯ 12 min. Reproducibility of Woods' algorithm was 2.2 Ϯ 0.8 mm with a time demand of 9 Ϯ 3 min. In 4 of the 15 cases, Woods' method failed. The mean deviation between all 3 methods was 2.3 Ϯ 0.8 mm. Conclusion: With a suitable user interface, interactive matching had the lowest registration error. The influence of subjectivity was shown to be negligible. Therefore, interactive matching is our preferred technique for image fusion of the brain. ://jnm.snmjournals.org/content/41/11/1823
American Journal of Roentgenology
ABSTRACT
Klinische Neurophysiologie, 2011
Journal of Nuclear Medicine
Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has d... more Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has delivered promising accuracy in the detection and validation of coronary lesions. Myocardial perfusion imaging (MPI) using SPECT is an established method for noninvasively assessing the functional significance of coronary stenoses and delivers valuable information for risk stratification. This retrospective analysis compared the accuracies of MDCT angiography and MPI in the detection of hemodynamically relevant lesions of the coronary arteries. Methods: Twenty-five patients with suspected or known coronary artery disease were studied. Electrocardiographically gated MPI and 16-MDCT angiography were performed. Myocardial perfusion images were analyzed by 2 experienced observers, and reversible and fixed perfusion defects were detected and allocated to their corresponding coronary vessels. For the evaluation of MDCT angiography, image quality was determined, and lesions Ն 50% and luminal narrowing Ͻ 50% were visually assessed and characterized by 2 independent observers unaware of the results of MPI. Results: Ninety-nine coronary vessels were analyzed, and the quality of MDCT angiography images was assessed for 330 coronary segments. Coronary artery diameter was interpretable for 231 (70%) of 330 segments, whereas in 99 (30%) of 330 segments, vessel diameter could not be evaluated because of heavy calcifications, blurring, motion artifacts, or intracoronary stents. MDCT angiography detected stenoses Ն 50% in 15 of 100 coronary arteries. Eight (53%) of 15 stenoses Ն 50% showed reversible or fixed perfusion defects in the corresponding myocardial areas on MPI. Sensitivity, specificity, and negative and positive predictive values were 100%, 87%, 100%, and 29%, respectively, for the ability of MDCT angiography to detect reversible perfusion de-fects in the corresponding myocardial areas. Conclusion: MDCT angiography detected myocardial ischemia, as defined by reversible perfusion defects on MPI, with a positive predictive value of 29% in a nonselected study cohort. Compared with MPI alone, MDCT angiography added important morphologic information, but MPI remains mandatory for evaluating the functional relevance of coronary artery lesions.
JAMA neurology, Jan 19, 2015
A 25-year-old right-handed physical education student was buried by an avalanche during a ski tou... more A 25-year-old right-handed physical education student was buried by an avalanche during a ski tour, resulting in 15 minutes of hypoxia. He developed posthypoxic intention myoclonus with involuntary myoclonic jerks of the mouth induced by talking and of both legs by walking. Both arms were unaffected. Weeks later when the patient was trying to solve sudoku puzzles, which he imagined in a 3-dimensional manner, he developed clonic seizures of the left arm associated with a right centroparietal seizure pattern on electroencephalography ( ; eFigure in the Supplement). The unilateral clonic seizures stopped immediately when the sudoku puzzle was discontinued. To solve a sudoku puzzle, every digit from 1 to 9 must appear in each of the 9 vertical columns, in each of the 9 horizontal rows, and in each of the 9 boxes.
Neuroradiology, 2015
Basilar artery (BA) perforator aneurysms may lead to severe subarachnoid hemorrhage (SAH). The ac... more Basilar artery (BA) perforator aneurysms may lead to severe subarachnoid hemorrhage (SAH). The acute management is uncertain. The anatomic approach is challenging both for coiling and clipping, and flow diverter stenting may be dangerous due to the required antiplatelet therapy. We report on our experiences in eight patients. We retrospectively analyzed eight patients with ruptured BA perforator aneurysm, including clinical characteristics, imaging data, treatment regimen, clinical course, and long-term outcome. Patients presented with major SAH and World Federation of Neurosurgical Societies (WFNS) scores of I in three, II in two, and V in three cases. In four patients, the aneurysm was detected in the initial angiography, in four only in follow-up angiography. Five patients were treated conservatively and three patients had endovascular therapy. In the conservative group, the aneurysm spontaneously thrombosed in three cases. One patient suffered from a re-SAH and stayed permanently dependent due to an associated perforator stroke (modified Rankin Scale (mRS) 5). The remaining four patients recovered well (mRS 0 and 1 in two cases, each) including three patients also exhibiting perforator strokes. Regarding the endovascular group, one parent vessel was an angioma feeder and embolized with Onyx. The second aneurysm spontaneously thrombosed periinterventionally. The third patient underwent coiling. Two parent vessels were occluded postinterventionally, resulting in perforator strokes. Final mRS scores were 0, 2, and 2, respectively. Conservative management of ruptured BA aneurysms might be a first-line treatment option with common spontaneous aneurysm occlusion, low rate of re-SAH, and promising clinical outcome.
Klinische Neurophysiologie, 2012
Journal of Nuclear Medicine
A wide range of techniques for registration of medical images has been devised in recent years. T... more A wide range of techniques for registration of medical images has been devised in recent years. The aim of this study is to quantify the overall spatial registration error of 3 different methods for image registration: interactive matching, surface matching, and uniformity index matching as described by Woods. Methods: MRI and ethylcysteinate dimer-SPECT images of the brain were registered for 15 patients. The matching error was assessed by determining intra-and interobserver variability of registrations. Quantification of the registration error was based on the mean spatial distance of 5000 voxels between 2 image positions. The mean position after repeated registrations in each patient was used as the gold standard. To evaluate the coherence of the 3 different registration methods, intermethod variability was determined. Results: Interactive matching showed an intraobserver/ interobserver variability of 1.5 Ϯ 0.3 mm/1.6 Ϯ 0.3 mm (mean Ϯ SD). The time demand for this method was 11 Ϯ 5 min. Surface matching revealed a variability of 2.6 Ϯ 1.1 mm/3.8 Ϯ 1.0 mm and a time demand of 26 Ϯ 12 min. Reproducibility of Woods' algorithm was 2.2 Ϯ 0.8 mm with a time demand of 9 Ϯ 3 min. In 4 of the 15 cases, Woods' method failed. The mean deviation between all 3 methods was 2.3 Ϯ 0.8 mm. Conclusion: With a suitable user interface, interactive matching had the lowest registration error. The influence of subjectivity was shown to be negligible. Therefore, interactive matching is our preferred technique for image fusion of the brain. ://jnm.snmjournals.org/content/41/11/1823
American Journal of Roentgenology
ABSTRACT
Klinische Neurophysiologie, 2011