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Dietbert Hahn

Publications and source records attributed to Dietbert Hahn.

34 records · Page 2Linked to original sources
PubMed2004

Cardiac and skeletal muscle involvement in myotonic dystrophy type 2 (DM2): a quantitative 31P-MRS and MRI study.

In myotonic dystrophy type 2 (DM2/PROMM), cardiac muscle involvement is usually more benign than in DM1, but clinically severe cardiomyopathy has been reported in some patients. Using a novel method of magnetic resonance spectroscopy (MRS), we examined the left ventricular myocardium and the left gastrocnemius muscle in 11 unselected DM2/PROMM patients without overt cardiac disease. Data on cardiac morphology and function were obtained by gradient echo two-dimensional cine magnetic resonance imaging (MRI); no significant differences were found between DM2 patients and healthy controls, but using a median split approach older patients showed mildly increased left ventricular (LV) volumes, i.e., 59% increase of end-systolic volume index (ESVI) and 35% increase of end-diastolic volume index (EDVI), and an increase of LV mass (26%). On cardiac MRS, DM2/PROMM patients showed a reduction of phosphocreatine (PCr) and adenosine triphosphate (ATP) by 25 and 20% compared to matched healthy controls. No significant differences were found between younger and older patients. In skeletal muscle of the DM2 patients, no significant decrease of PCr and ATP concentrations was found. However, in older patients, who commonly show overt hip flexor muscle weakness, we observed reduced values for PCr and ATP. Our MRS and MRI findings reveal evidence for subclinical cardiomyopathy in DM2/PROMM patients without overt heart disease. Future prospective studies are needed to clarify the risk of developing overt cardiac disease in DM2 and to define prognostic factors.

Adult↗
PubMed2003

Tumor volume as determined by computed tomography predicts local control in hypopharyngeal squamous cell carcinoma treated with primary surgery.

Computed tomography reliably evaluates hypopharyngeal squamous cell carcinomas (SCC) regarding the infiltration of specific anatomic structures and tumor volumes, both of which have been shown to be predictors of local control in patients treated with radiation therapy alone. However, an association of specific infiltrated structures and/or tumor volume with local control has not been investigated for surgical treatment; thus, we determined relationships of various infiltrated anatomic structures and tumor volume with local control in patients with hypopharyngeal SCC treated with primary surgery. In 45 hypopharyngeal SCC, tumor volumes were measured by pretreatment CT, and extent of tumor infiltration was determined by postoperative pathologic examination. All patients had clinical follow-up for recurrent tumor at the primary site. Statistical analysis basically consisted of chi-square and U-tests. Local control rate was 84.4% (38 of 45). Tumor volume was significantly associated with local control (p=0.004). Six of 16 (38%) patients with tumor volumes > or =8.1 cm3 (mean) had a local recurrence, which is significantly (p=0.003) more compared with 1 of 29 (3%) in the group of patients with volumes <8.1 cm3. Among all evaluated anatomic structures, only a tendency for significant association with local control was found for tumor involvement of the tonsils and the extralaryngeal soft tissues. The determination of tumor volumes by CT helps predict local control in patients with hypopharyngeal SCC treated with primary surgery.

Adult↗
PubMed2003

CT determination of lymphocytic infiltration around head and neck squamous cell carcinomas may be a predictor of lymph node metastases.

The histological detection of a peritumoral lymphocytic infiltration (PLI) and a sharp tumor border in patients with squamous cell carcinoma (SCC) of the larynx, pharynx or oral cavity is inversely correlated with the development of cervical lymph node metastases and is therefore a favorable prognostic factor. However, preoperative biopsies are often too small for an evaluation of these tumor features. Here, we examined retrospectively whether elevation of peritumoral density values as determined by contrast-enhanced computed tomography (CT) correlates with PLI and the presence of cervical lymph node metastases. A total of 40 patients with primarily resected SCC were studied (pT1=8, pT2=13, pT3=9, pT4=10); 25 patients were pN-positive. All tumors were histologically analyzed regarding PLI (present or not) and the tumor border (sharp or infiltrating). Based on standardized CT examinations (90 ml contrast agent at 1.5 ml/s), repeated region-of-interest (ROI)-based peritumoral density measurements were obtained. Correlations between CT density, PLI, tumor border and metastatic involvement of regional lymph nodes were statistically evaluated. CT densities were significantly higher (P<0.001) in patients with PLI and sharp tumor borders than in patients without PLI and patients with infiltrating tumor borders. Moreover, the presence of PLI, sharp tumor borders and elevated peritumoral CT densities were each correlated with the absence of lymph node metastases (P<0.001). An elevation of peritumoral CT densities is linked to PLI and sharp tumor borders on histology and a lower risk to develop lymph node metastases. For a patient-adapted therapy, these relations have to be prospectively evaluated regarding their prognostic relevance.

Adult↗
PubMed2003

Evaluation of sodium T1 relaxation times in human heart.

PURPOSE: To evaluate the sodium longitudinal relaxation (T(1)) characteristics for myocardium and blood in humans. MATERIALS AND METHODS: Eleven healthy volunteers were examined by using a (23)Na heart surface coil at a 1.5 T clinical scanner equipped with a broadband spectroscopy option. (23)Na MR measurements were performed by using a three-dimensional spoiled gradient echo sequence (in-plane resolution, 3.5 mm x 7 mm; slice thickness, 24 mm; TE, 3.1 msec; bandwidth, 65 Hz/pixel; TR, 21 to 150 msec). RESULTS: Longitudinal T(1) relaxation time components were 31.6+/-7.0 msec and 31.1+/-7.5 msec for myocardium and blood, respectively. CONCLUSION: (23)Na T(1) relaxation times of myocardium and blood can be determined in humans. The results are in agreement with values obtained from animal studies.

Adult↗
PubMed2003

Quantitative perfusion mapping of the human lung using 1H spin labeling.

PURPOSE: To evaluate the feasibility and reproducibility of a noninvasive, rapid and quantitative pulmonary perfusion mapping method using a two-compartment tissue model in combination with a (1)H spin labeling technique. MATERIALS AND METHODS: Ten healthy volunteers and three patients with cystic fibrosis (CF) were examined on a 1.5-T whole-body scanner. Global and selective lung T(1) maps based on an inversion recovery Snapshot FLASH technique were acquired from each subject with breath-holds at end-expiration. For comparison, corresponding Gd-DTPA-enhanced (1)H MR perfusion images were also obtained from each CF patient. RESULTS: Quantitative perfusion maps were calculated from the global and selective T(1) maps. The measured perfusion rates of the upper right lung in volunteers ranged from 400 to 600 mL/100 g/minute. The method showed a high intra-study reproducibility and low relative errors. In CF-patients, perfusion defects detected using Gd-DTPA-enhanced MR imaging were also detected using the spin labeling method. The perfusion rates of diseased lung tissues were less than 200 mL/100 g/minute. CONCLUSION: Noninvasive, robust and quantitative (1)H MR mapping of pulmonary perfusion was successfully performed using a rapid lung T(1) mapping in combination with spin labeling within the imaging slice. The proposed method has the potential to provide both important qualitative functional information and quantitative pulmonary perfusion rates in various lung diseases at various stages without the need of contrast agents.

Adult↗
PubMed2003

Auto-SENSE perfusion imaging of the whole human heart.

PURPOSE: To show the application of auto-sensitivity encoding (SENSE)-a self-calibrating parallel imaging technique-to first pass perfusion imaging of the whole human heart. MATERIALS AND METHODS: The self-calibrating parallel imaging method auto-SENSE was implemented for a saturation recovery turbo-fast low-angle shot (FLASH) sequence on a 1.5-T scanner using a standard four-element body phased array coil. By reducing the acquisition time per slice by a factor of two compared to conventional turbo FLASH imaging, the number of imaged slices could be doubled to six to ten with an unchanged temporal resolution of one image per heartbeat. This technique has been tested in eight healthy volunteers for contrast-enhanced heart perfusion imaging. RESULTS: Auto-SENSE heart perfusion imaging with improved coverage of the human heart could be performed successfully in all volunteers. A first quantitative comparison of perfusion values between the auto-SENSE and the non-SENSE techniques shows good agreement. CONCLUSION: Auto-SENSE allows perfusion imaging of the whole human heart without gaps.

Calibration↗
PubMed2003

Caffeine impairs intramuscular energy balance in patients susceptible to malignant hyperthermia.

Malignant hyperthermia (MH) is a metabolic myopathy with an abnormal release of calcium by the sarcoplasmic reticulum (SR), triggered by volatile anesthetics and succinylcholine. Similarly, caffeine enhances Ca(2+)release by the SR in vitro. In a prospective, randomized study, high-energy phosphates were studied by intramuscular 31-phosphorus magnetic resonance spectroscopy ((31)P-MRS) in 10 MH-susceptible (MHS) and 7 MH-nonsusceptible (MHN) subjects before and after injection of 0.5 ml caffeine (20 mM). Intramuscular energy balance, measured by the ratios of P(i)/PCr and P(i)/gamma-ATP, did not differ between MHS and MHN patients before and after intramuscular caffeine injection. However, within each group, P(i)/PCr and P(i)/gamma-ATP increased significantly only in the MHS group. Intramuscular caffeine injection seemed to impair the metabolic balance in MHS individuals. This may reflect a local calcium overload leading to consumption of high-energy phosphates and increase of inorganic phosphate. Intramuscular stimulation by caffeine and (31)P-MRS may provide a valuable tool to investigate MH-related metabolic disturbances.

Adult↗
PubMed2003

Non-invasive functional and biochemical assessment of mitoxantrone cardiotoxicity in patients with multiple sclerosis.

As mitoxantrone is a recently approved immunosuppressant for managing multiple sclerosis, the number of patients treated with this effective but potentially cardiotoxic anthracenedione derivative will increase substantially. To detect subclinical mitoxantrone-induced cardiotoxicity, sensitive non-invasive diagnostic tools are required. Assuming that changes in myocardial high-energy phosphate metabolism and alterations in left ventricular (LV) diastolic performance might be early markers of mitoxantrone-induced cardiotoxicity we examined fifteen MS patients treated with mitoxantrone up to 100 mg/m2 compared with 15 matched control MS patients. 31P-magnetic resonance (MR) spectroscopy was employed to measure myocardial high-energy phosphate metabolism, MR imaging for morphometric evaluation of changes in LV geometry. Indices of diastolic performance were assessed by Doppler echocardiography. In this exploratory study, phosphocreatine/ATP ratios were comparable between mitoxantrone-treated and control patients (1.48 +/- 0.23 and 1.43 +/- 0.41). LV mass, LV end-diastolic and systolic volumes, wall motion score, EF and cardiac output did not differ between both groups. All parameters of diastolic performance (E/A-ratio, isovolumic relaxation time, and E-wave deceleration time) were not different and within normal limits.In conclusion, using advanced diagnostic methodology, including functional, morphometric, and biochemical measurements no cardiotoxic effect of mitoxantrone up to a cumulative dose range of 100 mg/m2 could be detected.

Adolescent↗
PubMed2003

MR venography using an intravascular contrast agent: results from a multicenter phase 2 study of dosage.

OBJECTIVE: The objective of this study was to determine the optimal dose of the iron oxide contrast agent feruglose for contrast-enhanced MR venography of the abdominopelvic and lower extremity veins and to evaluate its safety and tolerability in patients with deep venous thrombosis. SUBJECTS AND METHODS: We enrolled in our study a total of 45 patients at six centers who had lower extremity deep venous thrombosis documented on radiographic venography. Forty-four patients received the study drug; 39 completed the study. Each patient received three sequential IV injections of feruglose at doses of 0.75, 1.25, and 3.0 mg Fe/kg body weight. MR venography at 1.5 T was repeated at three levels after each dose. Safety was evaluated. RESULTS: The agreement between contrast-enhanced MR venography and radiographic venography with regard to deep venous thrombosis above the knee was zero at the lowest dose (0.75 mg Fe/kg body weight), 43% at the dose 2.0 mg Fe/kg body weight, and 49% at the dose 5.0 mg Fe/kg body weight. No significant difference was seen between the two highest doses. The highest cumulative dose provided the greatest diagnostic usefulness score. No serious adverse events occurred. CONCLUSION: The two highest doses of feruglose showed the best agreement between contrast-enhanced MR venography and radiographic venography for deep venous thrombosis above the knee. The safety and tolerability of feruglose were confirmed.

Adult↗
PubMed2002

Absolute concentrations of high-energy phosphate metabolites in normal, hypertrophied, and failing human myocardium measured noninvasively with (31)P-SLOOP magnetic resonance spectroscopy.

OBJECTIVE: The purpose of the present study was to measure absolute concentrations of phosphocreatine (PCr) and adenosine triphosphate (ATP) in normal, hypertrophied, and failing human heart. BACKGROUND: Conflicting evidence exists on the extent of changes of high-energy phosphate metabolites in hypertrophied and failing human heart. Previous reports using phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) have quantified metabolites in relative terms only. However, this analysis cannot detect simultaneous reductions. METHODS: Four groups of subjects (n = 10 each), were studied: volunteers and patients with hypertensive heart disease (HHD), aortic stenosis, and dilated cardiomyopathy (DCM). Left ventricular (LV) function and mass were measured by cine magnetic resonance imaging. Absolute and relative concentrations of PCr and ATP were determined by (31)P-MRS with spatial localization with optimum point spread function. RESULTS: Left ventricular ejection fraction remained normal in HHD and aortic stenosis, but was severely reduced to 18% in DCM; LV mass was increased by 55%, 79%, and 68% respectively. In volunteers, PCr and ATP concentrations were 8.82 +/- 1.30 mmol/kg wet weight and 5.69 +/- 1.02 mmol/kg wet weight, and the PCr/ATP ratio was 1.59 +/- 0.33. High-energy phosphate levels were unaltered in HHD. In aortic stenosis, PCr was decreased by 28%, whereas ATP remained constant. In DCM, PCr was reduced by 51%, ATP by 35%, and reduction of the PCr/ATP ratio by 25% was of borderline significance (p = 0.06). Significant correlations were observed among energetic and functional variables, with the closest relations for PCr. CONCLUSIONS: In human heart failure due to DCM, both PCr and ATP are significantly reduced. Ratios of PCr to ATP underestimate changes of high-energy phosphate levels.

Adenosine Triphosphate↗
PubMed2002

Sodium T2* relaxation times in human heart muscle.

PURPOSE: To determine sodium transverse relaxation (T2*) characteristics for myocardium, blood and cartilage in humans. METHODS: T2* measurements were performed using a 3D ECG-gated spoiled gradient echo sequence. A 1.5 Tesla clinical scanner and a 23Na heart surface coil were used to examine eight healthy volunteers. In biological tissue, the sodium 23 nucleus exhibits a two-component T2 relaxation due to the spin 3/2 and its quadrupolar nature. The long T2* components of normal myocardium, blood, and cartilage were quantified. For myocardium, the T2* was determined separately for the septum, anterior wall, lateral wall, and posterior wall. RESULTS: The long T2* relaxation time components of 13.3 +/- 4.3 msec (septum 13.9 +/- 3.2 msec, anterior wall 13.8 +/- 5.4 msec, lateral wall 11.4 +/- 4.1 msec, posterior wall 14.1 +/- 3.7 msec), 19.3 +/- 3.3 msec, and 10.2 +/- 1.6 msec, were significantly different for myocardium, blood, and cartilage, respectively (P < 0.00001, Friedman's ANOVA). CONCLUSION: Measurement of 23Na T2* relaxation times is feasible for different regions of the human heart muscle, which might be useful for the evaluation of cardiac pathologies.

Adult↗
PubMed2002

Magnetization transfer short inversion time inversion recovery enhanced 1H MRI of the human lung.

The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli cause difficulty in 1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to perform lung anatomical imaging in eight healthy human subjects and five patients with cystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this approach has the potential for the evaluation of lung pathologies.

Adult↗
PubMed2002

Single-bolus technique for spiral CT of laryngopharyngeal squamous cell carcinoma: comparison of different contrast material volumes, flow rates, and start delays.

PURPOSE: To evaluate different contrast material volumes, flow rates, and start delays for contrast material enhancement of neck structures and squamous cell carcinoma to determine the most effective examination protocol. MATERIALS AND METHODS: Seventy patients with squamous cell carcinoma were prospectively randomized into four groups for examination with different protocols (125 mL of contrast material administered at a flow rate of 2.5 mL/sec, 100 mL at 2.0 mL/sec, 90 mL at 1.5 mL/sec, or 70 mL at 1.0 mL/sec). Dynamic series were performed on the tumors and relevant anatomic structures to obtain time-attenuation curves. The protocols were compared (analysis of variance and Tukey-Kramer tests) with regard to time and level of maximum tumor enhancement and carotid arterial enhancement of more than 150 HU. One selected protocol was tested in 30 additional routine examinations with start delays of 40 seconds (for laryngeal and/or hypopharyngeal tumors, 3-mm collimation) and 45 seconds (for oropharyngeal tumors, 5-mm collimation). RESULTS: Except for the 70-mL bolus administered at 1.0 mL/sec, the other protocols performed similarly well, yielding comparable maximum tumor enhancement at 52 seconds and later. In spite of a smaller volume of 90 mL, due to the prolonged flow time at 1.5 mL/sec, carotid arterial enhancement of more than 150 HU was prolonged (when compared with that in 100- or 125-mL protocols). As a result of these circumstances, injection of 90 mL at 1.5 mL/sec was considered more effective, providing no significant differences in tumor (P =.39) or carotid arterial (P =.52) enhancement between routine examinations and dynamic series. CONCLUSION: A single bolus of 90 mL administered at 1.5 mL/sec appears to be the most desirable protocol for contrast enhancement.

Adult↗
PubMed2002

Cardiac systolic rotation and contraction before and after valve replacement for aortic stenosis: a myocardial tagging study using MR imaging.

OBJECTIVE: Aortic stenosis leads to the derangement of cardiac function and contraction mode because of chronic pressure overload that is relieved after surgical valve replacement. The purpose of this study was to determine the changes in left ventricular systolic rotation and contraction using MR tagging in patients with aortic stenosis before and after surgical valve replacement compared with age-matched healthy volunteers. MATERIALS AND METHODS: Twelve patients with aortic stenosis were examined with an electrocardiographically triggered two-dimensional tagging sequence at 1.5 T before and 12 months after surgical valve replacement for the evaluation of wall function of the apical, mid ventricular, and basal levels. Eight healthy volunteers in the same age group served as the control group. RESULTS: Before surgery, all patients showed a significant increase of apical rotation (22.2 degrees +/- 5.9 degrees vs 10.3 degrees +/- 2.5 degrees, p < 0.0001) and overall left ventricular torsion (25.1 degrees +/- 6.6 degrees vs 14.5 degrees +/- 3.7 degrees, p < 0.001); basal rotation was not significantly different (-2.9 degrees +/- 2.1 degrees vs -4.2 degrees +/- 1.9 degrees, p = not significant) compared with the volunteer group. Apical rotation and torsion were negatively correlated with left ventricular mass (r = -0.73, p < 0.01, and r = -0.61, p < 0.05, respectively) and end-diastolic volume (r = -0.73, p < 0.01 and r = -0.64, p < 0.03, respectively). One year after surgery, basal rotation was reduced in the patients with aortic stenosis compared with the patients in the control group (-1.9 degrees +/- 1.8 degrees, p < 0.01). In comparison with preoperative values, apical rotation (14.2 degrees +/- 3.6 degrees, p < 0.01) also decreased but was still elevated, and this resulted in a normalization of left ventricular torsion (16.1 degrees +/- 3.7 degrees, p < 0.01). CONCLUSION: Surgical valve replacement for aortic stenosis leads to normalization of the left ventricular torsion 1 year after surgery. Pressure overload before surgery is associated with an increase of systolic left ventricular wringing motion, possibly serving as a compensatory mechanism. This mechanism declines with increasing left ventricular hypertrophy and dilatation.

Adult↗
PubMedDate not supplied

Time-resolved contrast-enhanced magnetic resonance angiography of the lower extremity.

The aim of this prospective study was to evaluate the feasibility and clinical use of time-resolved magnetic resonance angiography (MRA) of the lower extremity compared to intraarterial digital subtraction angiography (IA-DSA). Twenty-two patients suffering from peripheral arterial occlusive disease underwent MRA and IA-DSA. MRA examinations were performed on a 1.5 T system equipped with a 4-element-array coil. The area from the distal abdominal aorta to the distal lower limb was covered by 2-3 examination steps. A T1-weighted gradient echo sequence with a temporal resolution of 7-10 s was used. Single-dose contrast material (0.1 mm/kg) was injected with a flow rate of 2 mL/s, followed by a 40 mL saline flush. Pre and post contrast images were subtracted, and the subtracted data set was postprocessed with maximum intensity projection (MIP). In all patients diagnostic images could be obtained. Problems with venous overlay or incomplete arterial filling were not present. Sensitivity for the detection of relevant stenoses (>50%) was 96.7%, specificity was 97%. Concerning the detection of occlusions, sensitivity was 97.8%, specificity was 99.2%. Time-resolved contrast-enhanced MRA of the lower extremity is a robust procedure with high accuracy in the detection of relevant stenoses and occlusions.

Aged↗