Martin H K Hoffmann

Universität Ulm, Ulm, Baden-Wuerttemberg, Germany

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Publications (49)163.07 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to compare planimetric aortic valve area (AVA) measurements from 256-slice CT to those derived from transesophageal echocardiography (TEE) and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis. The study included 26 subjects (10 males, mean age: 79±6; range, 61-88 years). All subjects were clinically referred for aortic valve imaging prior to percutaneous aortic valve replacement from April 2008 to March 2009. Two radiologists, blinded to the results of TEE and cardiac catheterization, independently selected the systolic cardiac phase of maximum aortic valve area and independently performed manual CT AVA planimetry for all subjects. Repeated AVA measurements were made to establish CT intra- and interobserver repeatability. In addition, the image quality of the aortic valve was rated by both observers. Aortic valve calcification was also quantified. All 26 subjects had a high-grade aortic valve stenosis (systolic opening area <1.0 cm(2)) via CT-based planimetry, with a mean AVA of 0.62±0.18. In four subjects, TEE planimetry was precluded due to severe aortic valve calcification, but CT-planimetry was successfully performed with a mean AVA of 0.46±0.23 cm(2). Mean aortic valve calcium mass score was 563.8±526.2 mg. Aortic valve area by CT was not correlated with aortic valve calcium mass score. A bias and limits of agreement among CT and TEE, CT and cardiac catheterization, and TEE and cardiac catheterization were -0.07 [-0.37 to 0.24], 0.03 [-0.49 to 0.55], 0.12 [-0.39 to 0.63]cm(2), respectively. Differences in AVA among CT and TEE or cardiac catheterization did not differ systematically over the range of measurements and were not correlated with aortic valve calcium mass score. Planimetric aortic valve area measurements from 256-slice CT agree well with those derived from TEE and cardiac catheterization in high-risk subjects with known high-grade calcified aortic stenosis.
    European journal of radiology 10/2011; 80(1):151-7. · 2.65 Impact Factor
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    ABSTRACT: Dilatation of the infrarenal aortic segment determines the long-term outcome after endovascular repair of abdominal aortic aneurysms. This segment is crucial for sealing and preventing stent-graft migration. The purpose of this study was to evaluate influence of fixation mechanism on changes of supra- and infrarenal aortic diameters over a 10-year period. We reviewed all our endovascular procedures for abdominal aortic aneurysms and follow-up CT scans between 1998 and 2008. Only patients with the three most frequently implanted self-expandable stent-graft types and a minimal follow-up of three months were included in this study. Further inclusion criteria were elective repair and follow-up at our department to consistent data formats. A total of 103 patients, 35 with suprarenal fixation without hooks (Medtronic Talent®, Medtronic World Medical, Sunrise, FL, USA), 29 with suprarenal fixation with hooks (Cook Zenith®, Cook Inc. Bloomington, IN, USA) and 39 with infrarenal fixation with anchors (Gore Excluder®, W. L. Gore & Associates, Flagstaff, Ariz, USA) met the inclusion criteria. All measurements were performed in duplicate by two different investigators to determine intra- and interobserver errors. Based on this error a minimal change of 2 mm of infrarenal aortic neck diameter was determined as aortic neck dilatation. During a mean follow-up time of 39.4 (3-108.8) months, infrarenal aortic neck dilatation was found in 28.57% in the Medtronic group, 10.26% in the Gore group and 31.03 in the Cook group. Suprarenal changes were 17.14%, 20.51% and 17.24%, respectively. Reduction of the maximal diameter could be achieved in 74.3% (Medtronic), 79.5% (Gore), and 75.8% (Cook). Seven of 23 patients with a notable dilatation of the infrarenal neck required reintervention. All of them were stent-grafts with suprarenal fixation. No statistical significance was found between the 3 groups regarding changes of suprarenal or infrarenal diameters or migration rates. Although no statistical significance was found among the groups, infrarenal fixation showed the lowest rate of infrarenal dilatation.
    Zentralblatt für Chirurgie 10/2010; 135(5):433-7. · 0.69 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the potential clinical value of coronary plaque imaging with a new generation CT scanner and the interobserver variability of coronary plaque assessment with a new semiautomatic plaque analysis application. Thirty-five isolated plaques of the left anterior descending coronary artery from 35 patients were evaluated with a new semiautomatic plaque analysis application. All patients were scanned with a 256-slice MDCT scanner (Brilliance iCT, Philips Healthcare, Cleveland OH, USA). Two independent observers evaluated lesion volume, maximum plaque burden, lesion CT number mean and standard deviation, and relative lesion composition. We found 10 noncalcified, 16 mixed, and 9 calcified lesions in our study cohort. Relative interobserver bias and variability for lesion volume were -37%, -13%, -49%, -44% and 28%, 16%, 37%, and 90% for all, noncalcified, mixed, and calcified lesions, respectively. Absolute interobserver bias and variability for relative lesion composition were 1.2%, 0.5%, 1.5%, 1.3% and 3.3%, 4.5%, 7.0%, and 4.4% for all, noncalcified, mixed, and calcified lesions, respectively. While mixed and calcified lesions demonstrated a high degree of lesion volume interobserver variability, noncalcified lesions had a lower degree of lesion volume interobserver variability. In addition, relative noncalcified lesion composition had a very low interobserver variability. Therefore, there may a role for MDCT in serial noncalcified plaque assessment with semiautomatic analysis software.
    The international journal of cardiovascular imaging 03/2010; 26(6):711-20. · 2.15 Impact Factor
  • M. H. K. Hoffmann, O. Klass, H. Brunner
    Der Nuklearmediziner 01/2010; 33(02):105-112.
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    ABSTRACT: To compare image quality and effective radiation dose for prospectively gated axial CT coronary angiography on 64- and 256-slice CT. The patient cohort consisted of 80 consecutive patients undergoing imaging with 256-slice CT and 80 patients with 64-slice CT. The two patient groups were demographically matched according to age, gender, body mass index and heart rate. For both groups, two observers independently assessed image quality for all coronary segments on a five-point ordinal scale. The two groups were compared with regard to image quality and effective radiation dose. Image quality scores less than 3 were considered non-diagnostic. Mean effective radiation dose did not significantly differ between the two groups (3.4 +/- 0.8 mSv in both groups; p > 0.1). Vessel-based image quality was significantly better in patients undergoing 256-slice CT compared with those undergoing 64-slice CT (p < 0.001). The proportion of assessable coronary segments significantly increased from 95.6% in the 64-slice group to 98.9% in the 256-slice group (p < 0.05). Prospectively gated axial CT coronary angiography performed on 256-slice CT provides significantly improved and more stable image quality at an equivalent effective radiation dose compared with 64-slice CT.
    European Radiology 11/2009; 20(5):1124-31. · 4.34 Impact Factor
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    ABSTRACT: As diffusion-weighted imaging is increasingly implemented into routine protocols of abdominal MRI, abnormal findings in expected and unexpected locations become more common. The aim of our retrospective study was to investigate the specificity of restricted diffusion in differentiation of benign from malignant abdominal disease. Two hundred thirty consecutively registered patients underwent abdominal MRI including diffusion-weighted imaging (single-shot spin-echo echo-planar sequence) with b values of 0, 150, 500, and 1,000 s/mm(2). Lesions were detected by two blinded readers using only the images with a b value of 1,000 s/mm(2), and representative apparent diffusion coefficients were measured. Lymph nodes were not documented. Fifty-two of the 230 patients had a total of 55 lesions with restricted diffusion (23.9%). The mean apparent diffusion coefficient was 809 mm(2)/s. Forty-three lesions (78.2%) were malignant. The 12 benign lesions were liver hemangioma, liver adenoma, autoimmune pancreatitis, pancreatic teratoma, two abscesses, three cases of inflammatory bowel wall thickening due to Crohn's disease, Bartholin cyst, hemorrhagic ovarian cyst, and renal Rosai-Dorfman disease. Restricted diffusion is generally considered to be associated with malignant tumors because of the high cellularity of these tumors. However, in interpretation of diffusion-weighted images, it should be kept in mind that a number of benign lesions, as many as 22% in our cohort, can exhibit restricted diffusion on images with high b values, thus mimicking malignant lesions.
    American Journal of Roentgenology 10/2009; 193(4):1070-6. · 2.90 Impact Factor
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    ABSTRACT: The aim of this study was to investigate whether a respiratory biofeedback system could increase navigator efficiency and maintain image quality compared to conventional respiratory-gated magnetic resonance coronary angiography (MRCA). Eighteen healthy volunteers underwent MRCA using three different respiratory-gating protocols. A conventional expiratory free-breathing (FB) sequence was compared to two approaches using navigator echo biofeedback (NEB), a midinspiratory approach (NEBin) and an expiratory approach (NEBex). Navigator data reflecting the position of the diaphragm relative to a 3-mm gating window were made available to the subject using a video projector in combination with a Plexiglas screen and mirror goggles. Image quality was graded by two radiologists in consensus using a visual score ranging from 1 (not visible) to 4 (excellent vessel depiction). The NEB approaches improved navigator efficiency (71.1% with NEBex and 68.0% with NEBin vs 42.2% with FB), thus reducing total imaging time. This difference was statistically significant (P(NEBin)=.007; P(NEBex)=.001). Image quality in the NEBex group was comparable to that in the FB group (median score, 2.44 vs 2.52), but it proved to be significantly lower (median score, 1.94 vs 2.52) for the right coronary artery and the left anterior descending coronary artery in the NEBin group. NEB maintains image quality and significantly increases navigator efficiency, thereby decreasing total imaging time by about 40% compared to a conventional FB acquisition strategy.
    Academic radiology 04/2009; 16(3):374-9. · 2.09 Impact Factor
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    ABSTRACT: In this study, we investigated the influence of sublingual nitroglycerine (NTG) on the peripheral diameter, intraluminal contrast agent density, and image quality of coronary arteries during computed tomography coronary angiography (CTCA). Thirty patients with sublingual NTG application were matched to 30 patients without NTG. The diameters of the left anterior descending coronary artery (LAD), the left circumflex coronary artery and the right coronary artery were measured at 1-, 4-, and 8-cm length of each vessel as well as the intraluminal contrast agent density along the LAD. Vessel diameters and contrast attenuation at 4 and 8 cm were referenced against the values at 1 cm and processed as percentage reduction. Image quality of the posterior descending artery was assessed subjectively by 2 independent observers. The percentage of peripheral vessel diameter reduction and the peripheral attenuation of contrast agent density for all measured coronary arteries was significantly smaller in the group with NTG administration. The image quality of the posterior descending artery was significantly higher in the group with NTG. Sublingual administration of NTG before CTCA results in improved diagnostic image quality because of a significant dilatation and improved intraluminal contrast agent density of the peripheral vessels.
    Journal of computer assisted tomography 01/2009; 33(2):199-203. · 1.38 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2009; 181.
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2009; 181.
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    ABSTRACT: The purpose of this study was to investigate whether spectral computed tomography (CT) has the potential to improve luminal depiction by differentiating among intravascular gadolinium-based contrast agent, calcified plaque, and stent material by using the characteristic k edge of gadolinium. A preclinical spectral CT scanner with a photon-counting detector and six energy threshold levels was used to scan a phantom vessel. A partially occluded stent was simulated by using a calcified plaque isoattenuated to a surrounding gadolinium chelate solution. The reconstructed images showed an effective isolation of the gadolinium with subsequent clear depiction of the perfused vessel lumen. The calcified plaque and the stent material are suppressed.
    Radiology 11/2008; 249(3):1010-6. · 6.34 Impact Factor
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    ABSTRACT: Brain pulsation is a well-known observation in neurosurgery, but methods for its visualization on MR imaging, like phase imaging, do not provide a detailed structural view. We prospectively investigated electrocardiographic (ECG)-gated cine true fast imaging with steady-state precession (FISP) sequence on volunteers to test a sequence for demonstrating brain pulsation and movements of intracranial structures related to CSF dynamics. Eleven healthy volunteers were investigated with prospectively ECG-gated cine true-FISP in the midsagittal plane. A total of 50 phases were recorded per cardiac cycle and per volunteer. The lamina terminalis was chosen to study the pulsatility of the brain, and the optic recess diameter was chosen for means of objective quantification of the degree of pulsatility. Pulsatile motion of the lamina terminalis was apparent in all volunteers on the cine mode. The mean diameter of the optic recess was 2.5 mm. The greatest change in diameter in 1 volunteer was 1.5 mm. The mean change in diameter was 40% during 1 cardiac cycle. Cine true-FISP sequence is a well-suited method for investigations of passive movements of the ventricular system. It shows pulsations of the brain as well as passive changes caused by CSF dynamics with high temporal and spatial resolution.
    American Journal of Neuroradiology 11/2008; 30(1):199-202. · 3.17 Impact Factor
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    ABSTRACT: To assess image quality and radiation exposure with prospectively gated axial CT coronary angiography (PGA) compared to retrospectively gated helical techniques (RGH). Forty patients with suspected coronary artery disease (CAD) and a stable heart rate below 65 bpm underwent CT coronary angiography (CTCA) using a 64-channel CT system. The patient cohort consisted of 20 consecutive patients examined using a PGA technique and 20 patients examined using a standard RGH technique. Both groups were matched demographically according to age, gender, body mass index, and heart rate. For both groups, two independent observers assessed image quality for all coronary segments on an ordinal scale from 1 (nonassessable) to 5 (excellent quality). Image quality and radiation exposure were compared between patient groups. There were no significant differences in vessel-based image quality between the two groups (P > 0.05). Mean (+/- SD) effective radiation exposure in the PGA group was 3.7 +/- 0.8 mSv compared to 18.9 +/- 3.8 mSv in the RGH group without ECG-based tube current modulation (P < 0.001). Preliminary experience shows PGA technique to be a promising approach for CTCA resulting in a substantial reduction in radiation exposure with image quality comparable to that of standard RGH technique.
    European Radiology 11/2008; 19(4):829-36. · 4.34 Impact Factor
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    ABSTRACT: Contrast-enhanced multi-detector row helical CT angiography is establishing itself as an accurate, rapid, and non-invasive diagnostic modality in patients with acute gastrointestinal bleeding. On arterial phase MDCT images ongoing hemorrhage can be revealed as an area of active extravasation of contrast material within the bowel lumen. This pictorial essay gives a short overview of current diagnostic modalities in assessing acute GI tract bleeding, typical MDCT findings, and depicts potential pitfalls in the detection of acute GI bleeding with MDCT.
    Abdominal Imaging 08/2008; 34(4):476-82. · 1.91 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the accuracy of multi-detector row helical CT (MDCT) for detection and localization of acute upper and lower gastrointestinal (GI) hemorrhage or intraperitoneal bleeding. Thirty-six consecutive patients with clinical signs of acute bleeding underwent biphasic (16- or 40-channel) MDCT. MDCT findings were correlated with endoscopy, angiography or surgery. Among the 36 patients evaluated, 26 were examined for GI bleeding and 10 for intraperitoneal hemorrhage. Confirmed sites of GI bleeding were the stomach (n = 5), duodenum (n = 5), small bowel (n = 6), large bowel (n = 8) and rectum (n = 2). The correct site of bleeding was identifiable on MDCT in 24/26 patients with GI bleeding. In 20 of these 24 patients, active CM extravasation was apparent during the exam. Among the ten patients with intraperitoneal hemorrhage, MDCT correctly identified the bleeding source in nine patients. Our findings suggest that fast and accurate localization of acute gastrointestinal and intraperitoneal bleeding is achievable on MDCT.
    European Radiology 08/2008; 18(7):1406-13. · 4.34 Impact Factor
  • M Jeltsch, S Ranft, O Klass, A J Aschoff, M H K Hoffmann
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    ABSTRACT: Cardiovascular magnetic resonance imaging (CMR) has become an established noninvasive method for evaluating ventricular function utilizing three-dimensional volumetry. Postprocessing of volumetric measurements is still tedious and time consuming. Stroke volumes obtained by flow quantification across the aortic root or pulmonary trunk could be utilized to increase both speed of workflow and accuracy. To assess accuracy of stroke volume quantification using MR volumetric imaging compared to flow quantification in patients with various cardiac diseases. Strategies for the augmentation of accuracy in clinical routine were deduced. 78 patients with various cardiac diseases-excluding intra- or extracardiac shunts, regurgitant valvular defects, or heart rhythm disturbance-underwent cardiac function analysis with flow measurements across the aortic root and cine imaging of the left ventricle. Forty-six patients additionally underwent flow measurements in the pulmonary trunk and cine imaging of the right ventricle. Left ventricular stroke volume (LVSV) and stroke volume of the aortic root (SVAo) correlated with r=0.97, and Bland-Altman analysis showed a mean difference of 0.11 ml and a standard error of estimation (SEE) of 4.31 ml. Ninety-two percent of the data were within the 95% limits of agreement. Right ventricular stroke volume (RVSV) and stroke volume of the pulmonary trunk (SVP) correlated with a factor of r=0.86, and mean difference in the Bland-Altman analysis was fixed at -2.62 ml (SEE 8.47 ml). For RVSV and SVP, we calculated r=0.82, and Bland-Altman analysis revealed a mean difference of 1.27 ml (SEE 9.89 ml). LVSV and RVSV correlated closely, with r=0.91 and a mean difference of 2.79 ml (SEE 7.17 ml). SVAo and SVP correlated with r=0.95 and a mean difference of 0.50 ml (SEE 5.56 ml). Flow quantification can be used as a guidance tool, providing accurate and reproducible stroke volumes of both ventricles. Combining both offers a highly accurate tool to gauge ventricular function in a routine clinical setting, increasing workflow speed.
    Acta Radiologica 07/2008; 49(5):530-9. · 1.33 Impact Factor
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    ABSTRACT: The purpose of this study was to explore the accuracy of multi-detector row helical CT (MDCT), using a biphasic mesenteric angiography protocol for evaluation of acute mesenteric ischemia (AMI). In total, 79 consecutive patients with clinical signs of AMI underwent contrast enhanced 16- or 40-channel MDCT. MDCT findings were correlated with surgery, endoscopy and clinical outcome. Sensitivity, specificity, and positive and negative predictive values were calculated using the patients in which AMI had been excluded as a control group. In 28 patients the final diagnosis was AMI. In 27 patients (96.4%) MDCT correctly diagnosed AMI (specificity of 97.9%). A sensitivity of 93%, specificity of 100%, and positive and negative predictive values of 100% and 94%, respectively were achieved for the CT findings of visceral artery occlusion, intestinal pneumatosis, portomesenteric venous gas or bowel wall thickening in combination with either portomesenteric thrombosis or solid organ infarction. Our findings suggest that mesenteric MDCT angiography is an accurate tool for fast diagnostic work-up of patients with suspected AMI.
    Abdominal Imaging 05/2008; 34(3):345-57. · 1.91 Impact Factor
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    ABSTRACT: Contrast-enhanced multidetector row helical computed tomography (MDCT) scanning is establishing itself as a rapid, noninvasive, and accurate diagnostic method in suspected acute gastrointestinal bleeding. Active bleeding can be depicted as an area of focal high attenuation within the bowel lumen on arterial phase MDCT images. New MDCT technologies facilitate three-dimensional image reconstruction, and higher temporal resolution is available with new MDCT scanner generations. This allows for the acquisition of arterial- and portal-venous phase images of the whole abdomen, revealing potential bleeding sources and simultaneously depict morphological changes in the abdomen, such as intestinal tumors. This article gives an overview of available diagnostic modalities in assessing gastrointestinal (GI) tract hemorrhage, with a special emphasis on new MDCT technology.
    Abdominal Imaging 01/2008; 33(3):285-93. · 1.91 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2008; 180.
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    ABSTRACT: The purpose of this study was to analyze the pulmonary vessel enhancement obtainable using high-density contrast material and saline flushing with automated bolus tracking for multidetector-row computed tomographic (MDCT) pulmonary angiography in a routine clinical setting. Attenuation values of pulmonary vessels were retrospectively measured in 51 CT scans performed on a 40-channel MDCT for unselected emergency patients with clinically suspected pulmonary embolism. Mean vascular attenuation measured 326.7 +/- 104 Hounsfield units (HU) in the pulmonary trunk and 299.1 +/- 102 HU in the left distal lower lobe artery. Mean vascular attenuation values in the distal lower lobe artery were equal or higher than 150 HU for 94.1% (48/51) of patients. In conclusion, the combination of high-density contrast media and saline flushing with automated bolus tracking on a fast CT scanner reliably results in a homogenously high attenuation of pulmonary vessels, allowing precise delineation of clots down to the subsegmental level in MDCT pulmonary angiography.
    Journal of computer assisted tomography 01/2008; 32(6):893-8. · 1.38 Impact Factor

Publication Stats

1k Citations
163.07 Total Impact Points

Institutions

  • 2003–2010
    • Universität Ulm
      • Clinic of Diagnostic and Interventional Radiology
      Ulm, Baden-Wuerttemberg, Germany
  • 2006
    • Huazhong University of Science and Technology
      • Radiology Department
      Wuhan, Hubei, China