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Peter Hunold

Publications and source records attributed to Peter Hunold.

At least 19 recordsLinked to original sources
PubMed2006

Quantification of aortic valve stenosis in MRI-comparison of steady-state free precession and fast low-angle shot sequences.

We compared two different magnetic resonance (MR) sequences [steady-state free precession (SSFP) and gradient echo fast low-angle shot (FLASH)] for the assessment of aortic valve areas in aortic stenosis using transesophageal echocardiography (TEE) as the standard of reference. Thirty-two patients with known aortic stenosis underwent MR (1.5 T) using a cine SSFP sequence and a cine FLASH sequence. Planimetry was performed in cross-sectional images and compared to the results of the TEE. In seven patients the grade of stenosis was additionally assessed by invasive cardiac catheterization (ICC). The mean aortic valve area measured by TEE was 0.97+/-0.19 mm(2), 1.00+/-0.25 mm(2) for SSFP and 1.25+/-0.23 mm(2) based on FLASH images. The mean difference between the valve areas assessed based on SSFP and TEE images was 0.15+/-0.13 cm(2) (FLASH vs TEE: 0.29+/-0.17 cm(2)). Bland-Altman analysis demonstrated that measurements using FLASH images overestimated the aortic valve area compared to TEE. Comparing ICC with MRI and TEE, only a weak to moderate correlation was found (ICC vs TEE: R=0.52, p=0.22; ICC vs SSFP: R=0.20, p=0.65; ICC vs FLASH: R=0.16, p=0.70). Measurements of the aortic valve area based on SSFP images correlate better with TEE compared to FLASH images.

Aged↗
PubMed2006

Magnetic resonance cardiac perfusion imaging-a clinical perspective.

Coronary artery disease (CAD) with its clinical appearance of stable or unstable angina and acute myocardial infarction is the leading cause of death in developed countries. In view of increasing costs and the rising number of CAD patients, there has been a major interest in reliable non-invasive imaging techniques to identify CAD in an early (i.e. asymptomatic) stage. Since myocardial perfusion deficits appear very early in the "ischemic cascade", a major breakthrough would be the non-invasive quantification of myocardial perfusion before functional impairment might be detected. Therefore, there is growing interest in other, target-organ-specific parameters, such as relative and absolute myocardial perfusion imaging. Magnetic resonance (MR) imaging has been proven to offer attractive concepts in this respect. However, some important difficulties have not been resolved so far, which still causes uncertainty and prevents the broad application of MR perfusion imaging in a clinical setting. This review explores recent technical developments in MR hardware, software and contrast agents, as well as their impact on the current and future clinical status of MR imaging of first-pass myocardial perfusion imaging.

Contrast Media↗
PubMed2005

Myocardial infarct: depiction with contrast-enhanced MR imaging--comparison of gadopentetate and gadobenate.

Institutional review board approval and patient written informed consent were obtained. On two separate occasions, 24 hours apart, contrast-enhanced cardiac magnetic resonance (MR) imaging was performed prospectively at 1, 3, 5, 10, and 20 minutes after injection of gadopentetate dimeglumine and gadobenate dimeglumine in 15 patients (11 men, four women) with history of myocardial infarction. Both agents allowed detection of infarcted myocardium. T1 values at all times were significantly (P < .05) lower for gadobenate, compared with values for gadopentetate, in both infarcted and noninfarcted myocardium. At 1 minute after administration of both agents, T1 values in left ventricular cavity (LVC) were not different; at 3-20 minutes after injection, values were significantly (P < .05) lower for gadobenate. Differences between contrast-to-noise ratio (CNR) values of infarcted and noninfarcted myocardium were significantly higher on gadobenate-enhanced images (P < .05). CNR values between infarcted myocardium and LVC were significantly higher on gadopentetate-enhanced images (P < .05). Gadopentetate might permit better delineation of infarcts, especially subendocardial infarcts.

Aged↗
PubMed2005

Broad-beam spectral Doppler sonification of the vena contracta using matrix-array technology: A new solution for semi-automated quantification of mitral regurgitant flow volume and orifice area.

OBJECTIVES: The objective of this study was to evaluate broad-beam spectral Doppler sonification of the vena contracta using a matrix-array transducer for quantification of mitral regurgitation (MR). BACKGROUND: Noninvasive assessment of the severity of valvular regurgitation remains challenging. A recent technique measures regurgitant flow directly at the vena contracta based on the product of velocity times backscattered Doppler power (proportional to orifice area). That approach, however, has been limited by relatively narrow conventional beamwidths. Matrix-array transducers, recently developed for three-dimensional imaging, can potentially provide broader beams. Therefore, we addressed the hypothesis that deliberate broadening of the Doppler beam can encompass larger regurgitant cross-sectional areas to capture a broader range of regurgitant flows. METHODS: A matrix-array transducer system was modified to provide a three-dimensionally expanded spectral Doppler sample volume. Calculations of orifice area, flow rate, and regurgitant stroke volume (RSV) from Doppler power were automated on board a routinely used echocardiographic scanner and tested in vitro. In 24 patients with isolated MR, RSV was compared with magnetic resonance imaging (MRI) mitral inflow minus aortic outflow from phase-velocity maps. RESULTS: The calculated flow rate and RSV correlated and agreed well with reference values in vitro (r = 0.98 to 0.99) and in patients (r = 0.93, mean difference 0.4 +/- 3.2 ml, p = NS vs. 0), with sufficient sonification to measure flow orifices up to 0.85 cm in diameter. Agreement with MRI was comparable in 17 patients with central and seven with eccentric jets (p = NS vs. 0). CONCLUSIONS: The broad-beam spectral Doppler technique provides accurate, largely automated quantification of regurgitant flow rate and integrated RSV directly at the lesion. The accuracy related to broader sonification is made possible by the new matrix-array transducer design.

Adult↗
PubMed2005

Parallel acquisition techniques for accelerated volumetric interpolated breath-hold examination magnetic resonance imaging of the upper abdomen: assessment of image quality and lesion conspicuity.

PURPOSE: To evaluate the impact of parallel acquisition techniques (PATs) on image quality and detection of liver metastases using three-dimensional volumetric interpolated breath-hold examination (VIBE) for clinical liver imaging. MATERIALS AND METHODS: Forty-nine patients with various primary malignancies underwent abdominal dynamic contrast-enhanced three-dimensional VIBE magnetic resonance imaging (MRI) (1.5 T) using a standard phased array coil. Recently introduced Generalized Autocalibrating Partially Parallel Acquisition (GRAPPA) and SENSitivity Encoding (mSENSE) PAT reconstruction algorithms were added to reduce scan time twofold. Overall image quality, motion, and aliasing artifacts were classified on a 5-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements were performed for quantitative comparison. All sequences were evaluated concerning the number of detected lesions. RESULTS: PAT resulted in a reduction of data acquisition time from 23 to 13 seconds. Both GRAPPA and mSENSE data sets yielded 30% less SNR (34.8 +/- 14.1 and 33.1 +/- 13.3, P < 0.001) and 35% less CNR (21.2 +/- 15.0 and 20.9 +/- 12.7, P < 0.05) in comparison to unaccelerated VIBE (SNR = 50.8 +/- 20.3/CNR = 32.5 +/- 19.1). Similarly, PAT revealed lower-image-quality scores than unaccelerated VIBE. GRAPPA resulted in more fold-over artifacts than mSENSE. mSENSE revealed slightly fewer motion artifacts than no PAT. The unaccelerated late-venous-phase VIBE sequence revealed 146 lesions in the same patients. Accelerated images with mSENSE reconstruction detected 138 lesions. GRAPPA revealed 127 lesions, and thus performed inferior to mSENSE. CONCLUSION: At least for arrays with small numbers of elements, such as arrays used in this study, the PAT-induced reduction in scanning times must be weighed against compromises in image quality, which translate into poorer diagnostic performance regarding detection of small hepatic lesions. Thus, the PAT implementations tested in this study should probably be reserved for patients unable to hold their breaths for regular three-dimensional VIBE data sets.

Abdomen↗
PubMed2005

[Non-compaction cardiomyopathy].

Isolated non-compaction of the ventricular myocardium (INVM), also known as left ventricular hypertrabeculation or spongy myocardium, belongs to the "unclassified" cardiomyopathies according to the World Health Organization. The main characteristic of this entity is a prominent trabeculation of the left ventricle with deep intertrabecular recesses communicating with the ventricular cavity. The pathomechanism of INVM is thought to be an arrest in cardiac myogenesis with persistence of embryonic myocardial morphology. The most frequent clinical manifestations include congestive heart failure, ventricular arrhythmias and systemic thromboembolic events. The therapy of INVM comprises standard medical therapy for heart failure.

Cardiomyopathies↗
PubMed2005

Late enhancement: a new feature in MRI of arrhythmogenic right ventricular cardiomyopathy?

Aim of the study was to evaluate whether late enhancement (LE) in contrast-enhanced MRI can be used to characterize fibrofatty myocardial replacement in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC). Fifteen patients with suspected ARVC underwent CE-MRI using a 1.5 T scanner. Long and short axis SSFP cine images and T1-weighted fast spin echo images were collected in all patients. After injection of 0.2 mmol/kg Gd-DTPA (Magnevist, Schering, Berlin, Germany), inversion recovery gradient echo images were acquired in long and contiguous short axes to detect myocardial LE indicating areas of fibrous tissue within the myocardium. For definition of ARVC, the ESC Task force criteria were used. In 7 (47%) of 15 patients, ARVC was diagnosed based on the ESC criteria. In all of these 7 patients, MRI showed morphologic or functional criteria of ARVC according to the ESC. LE of the right ventricular myocardium was detected in 5 (71%) of the 7 ARVC patients, additional LE of the left ventricular myocardium in 2 of these patients. None of the 7 patients meeting the ARVC diagnostic criteria had fatty RV infiltration demonstrable by conventional T1-weighted imaging. Eight patients neither showed morphologic criteria of ARVC nor LE. In conclusion, late enhancement can be detected in the right and left ventricular myocardium in some ARVC patients. LE might represent intramyocardial areas of fibrous tissue.

Adult↗
PubMed2005

Full-body cardiovascular and tumor MRI for early detection of disease: feasibility and initial experience in 298 subjects.

OBJECTIVE: High diagnostic accuracy, emerging whole-body concepts, and lack of side effects combine to render MRI a natural candidate for screening purposes. The aim of this study was to evaluate the technical feasibility of a comprehensive multiorgan-targeting MRI examination and determine the frequency of findings in subjects without a history of serious disease. SUBJECTS AND METHODS: The study group was composed of 331 subjects. The MRI protocol (mean examination time, 63 min) encompassed the target organs: the brain, arterial system, heart, and colon. Diagnoses were deemed relevant if the physician had to inform the subject about the findings. Subjects with a history of serious illnesses were excluded from subsequent analysis (n=33). All analyses were performed for the resulting subgroup of 298 subjects (247 men, 51 women; mean age, 49.7 years). RESULTS: All 298 examinations were diagnostic excluding eight MR colonography components in which remaining stool hampered reliable diagnosis. Follow-up or radiologic confirmation could be obtained in 75% of all cases with relevant findings (128/169); only one false-positive result was encountered. Of the study group, 21% exhibited signs of atherosclerotic disease. Two cerebral infarctions and one myocardial infarction, previously unknown, were encountered; 12% had peripheral vascular disease. Twelve colonic polyps and nine pulmonary lesions were correctly detected. Of all MRI examinations, 29% revealed relevant additional findings in nontargeted organs. Only one minor allergoid reaction was encountered. CONCLUSION: The presented data point toward an increased use of MRI for screening in the future, but to date screening MRI should not be performed outside a research setting because the cost-benefit relation is unclear.

Adult↗
PubMed2005

Assessment of left ventricular parameters using 16-MDCT and new software for endocardial and epicardial border delineation.

OBJECTIVE: The purpose of our study was to quantify left ventricular function and mass derived from retrospectively ECG-gated 16-MDCT coronary angiography data sets using a new analysis software based on automatic contour detection in comparison to corresponding standard of reference measurements acquired with MRI. SUBJECTS AND METHODS: Multiplanar reformations in the short-axis orientation were calculated from axial contrast-enhanced CT images in 18 patients (men, 15; women, three; age range, 38-70 years; mean, 57.4 +/- 10.2 [SD] years) who were referred for CT coronary angiography. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and left ventricular mass (LVM) were analyzed with a recently developed imaging software using an automated contour detection algorithm of left ventricular endo- and epicardial contours and by manual tracing. The data were compared with similar measurements on MRI as the standard of reference. RESULTS: EDV, ESV, EF, and LVM derived from an automated contour detection algorithm were not statistically significantly different from manual tracing (CT(auto) vs CT(manual): EDV = 137.1 +/- 45.7 mL vs 134.2 +/- 39.9 mL, ESV = 58.8 +/- 34.2 mL vs 58.1 +/-30.1 mL, EF = 59.2% +/- 13.7% vs 58.1% +/- 12.0%, LVM = 130.9 +/- 29.1 g vs 133.7 +/- 33.2 g; p > 0.05). However, EDV (118.7 +/- 43.6 mL), ESV (50.1 +/- 33.5 mL), and LVM (142.8 +/-38.4 g) as calculated on MR data sets were statistically significantly different from those calculated on CT (p < 0.05), whereas MRI-based EF (59.9% +/- 14.4%) did not differ statistically significantly from those based on both CT algorithms (p > 0.05). CONCLUSION: Automatic and manual analysis of data acquired during CT coronary angiography using a 16-MDCT scanner allows a reliable assessment of left ventricular ejection fraction and a rough estimation of left ventricular volumes and mass.

Adult↗
PubMed2005

Myocardial late enhancement in contrast-enhanced cardiac MRI: distinction between infarction scar and non-infarction-related disease.

OBJECTIVE: Our objective was to assess and compare the patterns of late enhancement (LE) in contrast-enhanced cardiac MRI caused by myocardial infarction and different myocardial diseases that are not related to ischemic infarction. MATERIALS AND METHODS: A total of 811 consecutive contrast-enhanced cardiac MRI studies performed for different indications were reviewed for left ventricular myocardial LE after gadopentetate dimeglumine administration. MRI studies were performed on a 1.5-T scanner using an inversion recovery turbo FLASH sequence (TR/TE, 8/4 msec; flip angle, 25 degrees). The LE pattern of ischemic infarction scar was compared with that in nonischemic myocardial disease. RESULTS: LE was found in 421 (52%) patients. In all patients with myocardial infarction, LE included the subendocardial layer. Nineteen patients without history of myocardial infarction and angiographically excluded coronary artery disease showed different patterns of LE caused by myocarditis, sarcoidosis, arrhythmogenic right ventricular dysplasia, cardiomyopathy, endomyocardial fibrosis, and iatrogenic scars after biopsy, ablation of septal hypertrophy, and myocardial laser revascularization. CONCLUSION: LE in contrast-enhanced cardiac MRI is not specific for ischemic infarction. LE in ischemic infarction always involves the subendocardial layer, whereas it does not necessarily do so in other myocardial diseases. Therefore, if LE omit the subendocardial layer, different nonischemic myocardial diseases have to be considered. The pattern of LE might be helpful for the differential diagnosis of myocardial disease and in distinguishing it from ischemic disease.

Adult↗
PubMed2004

Venous compression at high-spatial-resolution three-dimensional MR angiography of peripheral arteries.

The aim of this study was to assess a venous compression technique that is performed with contrast material-enhanced peripheral magnetic resonance (MR) angiography to reduce venous enhancement. Healthy volunteers, as well as patients with correlating digital subtraction angiographic (DSA) findings, were examined. Venous compression was accomplished by placing a cuff at the midfemoral level unilaterally. Arterial signal-to-noise and contrast-to-noise ratios indicated no significant differences between compressed and noncompressed legs. Venous overlay was substantially reduced in the compressed legs. MR angiography with venous compression yielded diagnostic image quality and results that had excellent correlation with DSA findings. High-spatial-resolution peripheral MR angiography of improved diagnostic quality appears feasible, even with long data acquisition times.

Adult↗
PubMed2004

Coronary artery calcium score: influence of reconstruction interval at 16-detector row CT with retrospective electrocardiographic gating.

In 30 patients, Agatston and volumetric scores were assessed by using retrospectively gated multi-detector row computed tomography (CT). For each patient, 10 data sets were created at different times and were evenly spaced throughout the cardiac cycle. For each reconstruction, patients were assigned a percentile that described the level of cardiovascular risk. Nineteen (63%) of 30 patients could be assigned to more than one risk group depending on the reconstruction interval used. Agatston and volumetric scores both proved highly dependent on the reconstruction interval used (coefficient of variation, < or =63.1%) even with the most advanced CT scanners. Accurate and reproducible quantification of coronary calcium seems to require analysis of multiple reconstructions.

Adult↗
PubMed2004

Noninvasive visualization of coronary artery bypass grafts using 16-detector row computed tomography.

OBJECTIVES: The aim of this study was to evaluate the diagnostic accuracy of a 16-detector row computed tomography (CT) scanner for the assessment of coronary artery bypass grafts. BACKGROUND: A new generation of multislice spiral CT scanners, equipped with more and thinner detector rows, allows for reliable noninvasive detection of obstructive coronary artery disease. METHODS: The study included 51 consecutive patients. Three patients had to be excluded from the study due to arrhythmias or fast heart rates despite beta-blockade. A total of 48 patients with 131 coronary artery bypass grafts (internal mammary artery, n = 40; venous grafts, n = 91) were examined by computed tomography angiography (CTA) and by invasive coronary angiography (ICA) using a 16-detector row CT scanner. For cardiac protocols, only the 12 inner detector rings are applied. All CT examinations were performed with retrospective electrocardiogram gating at a mean heart rate of 64 +/- 5 beats/min; 120 ml of Xenetix 300 (Guerbert GmbH, Sulzbach, Germany) were continuously injected. The bypass graft patency and the presence of stenoses as well as the proximal and distal anastomoses were evaluated by two experienced readers. RESULTS: All bypass grafts and 74% of the distal bypass anastomoses could be visualized by CTA; 21 bypass graft occlusions and 1 significant stenosis were detected by CTA and confirmed by ICA. Five false positive and one false negative finding resulted in a sensitivity of 96%, a specificity of 95%, a positive predictive value of 81%, and a negative predictive value of 99%. CONCLUSIONS: Sixteen-detector row CT scanner technology allows for the reliable visualization of coronary bypass grafts. Dysfunctional bypass grafts can be detected with high diagnostic accuracy. This technology can be used as a noninvasive test for patients with suspected graft dysfunction.

Aged↗
PubMed2004

Increased time rate of change of gradient fields: effect on peripheral nerve stimulation at clinical MR imaging.

PURPOSE: To increase gradient stimulation from 100% to a fixed 120% level and to assess patient acceptance of the degree of peripheral nerve stimulation (PNS) at magnetic resonance (MR) imaging. MATERIALS AND METHODS: Two hundred ten patients underwent MR imaging of various body regions according to clinical indications. An additional three-dimensional fast low-angle shot sequence with the 120% stimulation level was performed. A patient questionnaire was distributed after MR imaging to document the presence, degree, and location of PNS. Degree was measured with an 11-point scale (score range, 0-10). Age was analyzed between the sexes for significant statistical differences. Furthermore, correlation between location of examination and location and degree of stimulation was performed. To determine stimulation discomfort relative to other factors typically present at MR imaging, the degree of discomfort due to room temperature, size of magnet bore, acoustic noise, examination time, and heating sensation was determined for comparison, as well. RESULTS: Thirty-five (16.7%) patients reported a stimulation sensation during imaging in one or more locations, while six (2.9%) felt very uncomfortable local stimulation (score of 8-10). No significant difference between male and female patients regarding age, sex, and appearance or degree of stimulation sensation could be detected. No significant correlation between location of examination and location and degree of stimulation was recorded. Compared with other side effects, PNS was considered relatively unimportant. CONCLUSION: The 120% gradient stimulation level seems acceptable for routine clinical imaging with this gradient system, since only 2.9% of patients experienced very uncomfortable local stimulation.

Adolescent↗
PubMed2004

MRI in coronary artery disease.

Diagnosis of coronary artery disease (CAD) is a major challenge for medical imaging, because CAD is the leading cause of death in developed nations. Several non-invasive tests are used in clinical routine for the detection of CAD. However, due to limited sensitivity and specificity, the reliable diagnosis as well as the exclusion of CAD can only be established by catheter angiography. In patients with known CAD, therapeutic decisions require accurate information on myocardial function, ischemia and viability. Recently, magnetic resonance (MR) imaging has emerged as a non-invasive cardiac imaging technique that provides information on cardiac morphology, cardiac function, myocardial viability, and coronary morphology. This review discusses technical aspects and the clinical impact of different MR techniques.

Clinical Trials as Topic↗
PubMed2004

MR-based full-body preventative cardiovascular and tumor imaging: technique and preliminary experience.

Recent improvements in hardware and software, lack of side effects, as well as diagnostic accuracy make magnetic resonance imaging a natural candidate for preventative imaging. Thus, the purpose of the study was to evaluate the feasibility of a comprehensive 60-min MR-based screening examination in healthy volunteers and a limited number of patients with known target disease. In ten healthy volunteers (7 men, 3 women; mean age, 32.4 years) and five patients (4 men, 1 woman; mean age, 56.2 years) with proven target disease we evaluated the performance of a comprehensive MR screening strategy by combining well-established organ-based MR examination components encompassing the brain, the arterial system, the heart, the lungs, and the colon. All ten volunteers and five patients tolerated the comprehensive MR examination well. The mean in-room time was 63 min. In one volunteer, insufficient colonic cleansing on the part of the volunteer diminished the diagnostic reliability of MR colonography. All remaining components of the comprehensive MR examination were considered diagnostic in all volunteers and patients. In the five patients, the examination revealed the known pathologies [aneurysm of the anterior communicating artery ( n=1), renal artery stenosis ( n=1), myocardial infarct ( n=1), and colonic polyp ( n=2)]. The outlined MR screening strategy encompassing the brain, the arterial system, the heart, the lung, and the colon is feasible. Further studies have to show that MR-based screening programs are cost-effective in terms of the life-years saved.

Adult↗
PubMed2004

Imaging of myocardial perfusion with magnetic resonance.

Coronary artery disease (CAD) is currently the leading cause of death in developed nations. Reflecting the complexity of cardiac function and morphology, noninvasive diagnosis of CAD represents a major challenge for medical imaging. Although coronary artery stenoses can be depicted with magnetic resonance (MR) and computed tomography (CT) techniques, its functional or hemodynamic impact frequently remains elusive. Therefore, there is growing interest in other, target organ-specific parameters such as myocardial function at stress and first-pass myocardial perfusion imaging to assess myocardial blood flow. This review explores the pathophysiologic background, recent technical developments, and current clinical status of first-pass MR imaging (MRI) of myocardial perfusion.

Coronary Circulation↗