Are Sonographically Measured Vascular Haemodynamic Parameters Reproducible Using Magnetic Resonance Imaging?

OBJECTIVE/BACKGROUND: Hemodynamic measurements of blood flow in the common femoral vein and artery can be performed readily using duplex sonography. The ratio of venous to arterial volume flow in these vessels, the venous arterial flow index (VAFI), is increased in patients with varicose veins and/or chronic venous disease. The objective was to determine the reproducibility of sonographically measured hemodynamic flow parameters using phase contrast magnetic resonance imaging (MRI). METHODS: Based on hemodynamic volume flow measurements from the common femoral vein and artery the VAFI was calculated in seven patients with varicose veins (C2, Ep, As, Pr) and 32 healthy controls using standard duplex sonography and MRI. RESULTS: Based on duplex sonography, the average VAFI (VAFI_d) was 1.05 ± 0.17. The same ratio, using MRI (VAFI_mri) was 1.05 ± 0.19. There was a significant correlation between the VAFI_d and the VAFI_MRI (p = .0021). In patients with venous disease, the average VAFI_d and VAFI_mri were 1.36 ± 0.21 and 1.36 ± 0.20, respectively. In contrast, in the healthy cohort the VAFI_d was 1.00 ± 0.12 and the VAFI_mri measured 1.01 ± 0.15. As expected, there was a significant difference between the VAFI measured in those with venous disease when compared with that of healthy controls (p < .0001). CONCLUSION: There is a significant correlation between the VAFI measured using sonography and MRI. The study confirmed the elevation of VAFI in patients with chronic venous disease.

Radiotherapy beyond cancer: target localization in real-time MRI and treatment planning for cardiac radiosurgery.

PURPOSE: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. METHODS: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. RESULTS: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior-inferior), 2.4 mm (anterior-posterior), and 2 mm (left-right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising either normal tissue dose constraints or PTV coverage. The magnetic field caused a slight increase in the PTV dose with the in-line MRI-Linac configuration. CONCLUSIONS: The authors' results indicate that real-time tracking and motion compensation are mandatory for cardiac radiosurgery and MRI-guidance is feasible, opening the possibility of treating cardiac arrhythmia patients completely noninvasively.

High-Intensity Focused Ultrasound Ablation of Uterine Fibroids - Potential Impact on Fertility and Pregnancy Outcome.

Laparoscopic myomectomy is regarded as the gold standard for women with symptomatic fibroids who wish to become pregnant. High-intensity focused ultrasound (HIFU or MRgFUS) ablation of uterine fibroids is also being discussed as a non-surgical, minimally invasive, therapeutic option. This review examines the available data on the impact of HIFU/MRgFUS on fertility and pregnancy, focusing particularly on potential direct side-effects of this type of intervention on ovaries, fallopian tubes and uterus and potential late effects on pregnancy and birth, based on the current literature. All pregnancies after HIFU/MRgFUS published to date (around 100 cases) were evaluated. The published case series suggest that HIFU/MRgFUS ablation has no impact on the rate of miscarriages or other obstetrical outcome parameters. Because no prospective studies exist which permit firm conclusions to be drawn on the impact of HIFU/MRgFUS on fertility and pregnancy outcome in women with symptomatic fibroids, this approach is currently only recommended for women with suspected fertility problems due to uterine fibroids who either decline surgery or who have an unacceptably high surgical risk.

MR-guided HIFU treatment of symptomatic uterine fibroids using novel feedback-regulated volumetric ablation: effectiveness and clinical practice.

PURPOSE: To evaluate a novel feedback-regulated volumetric sonication method in MR-guided HIFU treatment of symptomatic uterine fibroids. MATERIALS AND METHODS: 27 fibroids with an average volume of 124.9 ± 139.8 cc in 18 women with symptomatic uterine fibroids were ablated using the new HIFU system Sonalleve (1.5 T MR system Achieva, Philips). 21 myomas in 13 women were reevaluated 6 months later. Standard (treatment) cells (TC) and feedback-regulated (feedback) cells (FC) with a diameter of 4, 8, 12, and 16 mm were used and compared concerning sonication success, diameter of induced necrosis, and maximum achieved temperature. The non-perfused volume ratio (NPV related to myoma volume) was quantified. The fibroid volume was measured before, 1 month, and 6 months after therapy. Symptoms were quantified using a specific questionnaire (UFS-QoL). RESULTS: In total, 205 TC and 227 FC were applied. The NPV ratio was 23 ± 15 % (2 - 55). The TC were slightly smaller than intended (-3.9 ± 52 %; range, -100 - 81), while the FC were 20.1 ± 25.3 % bigger (p = 0.02). Feedback mechanism is less diversifying in diameter (p < 0.001). Overall, the FC correlate well with the planned treatment diameter (r = 0.79), other than the TC (r = 0.38). Six months after therapy, the fibroid volume was reduced by 45 ± 21 % (5 - 100) (p = 0.001). The symptoms decreased significantly (p = 0.001). No serious adverse events were recorded. CONCLUSION: Use of volumetric sonication leads to homogenous heating and sufficient necrosis. It is a safe and effective therapy for treating symptomatic uterine fibroids. Successful sonication of feedback cells leads to more contiguous necrosis in diameter and a less diversifying temperature. KEY POINTS: ▶ MR-guided HIFU ablation of symptomatic uterine fibroids is a valuable treatment option. ▶ By non-invasive HIFU fibroid volumes can be reduced and symptoms improved. ▶ The novel feedback-regulated treatment cells offer advantages over standard treatment cells.

[MRI for arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C)]. / MRT bei arrhythmogener rechtsventrikulärer Dysplasie/Kardiomyopathie (ARVD/C).

Arrhythmogenic right ventricular dysplasia/cardiomyopathy is a congenital disease that may present with sudden cardiac death as the first manifestation. Standards for the difficult clinical diagnosis are the so-called modified Task Force criteria that incorporate imaging-based, electrocardiographic and anamnestic information. Cardiac magnetic resonance imaging (MRI) is the standard technique for imaging of the right ventricle and can compliment the recent ARVD/C diagnosis criteria by providing exact information on right ventricular size and function. It is the most reliable modality available for the detection of right ventricular aneurysms and the quantification of ventricular size. Furthermore, MRI is able to identify areas of fatty or fibrous replacement within the right ventricular myocardium in a non-invasive way. However, a suspicion of ARVD/C cannot be confirmed or excluded based on MRI findings alone. In clinical routine cardiac MRI is an enormously important component in the ARVD/C diagnostic toolbox; however, MRI can only act as one part of the diagnostic puzzle and should exclusively be performed by experienced centers using specifically tailored protocols.

MR-guided HIFU treatment of symptomatic uterine fibroids using novel feedback-regulated volumetric ablation: effectiveness and clinical practice.

PURPOSE: To evaluate a novel feedback-regulated volumetric sonication method in MRguided HIFU treatment of symptomatic uterine fibroids. MATERIALS AND METHODS: 27 fibroids with an average volume of 124.9 ± 139.8 cc in 18 women with symptomatic uterine fibroids were ablated using the new HIFU system Sonalleve (1.5 TMR system Achieva, Philips). 21 myomas in 13 women were reevaluated 6 months later. Standard (treatment) cells (TC) and feedback-regulated (feedback) cells (FC) with a diameter of 4, 8, 12, and 16 mm were used and compared concerning sonication success, diameter of induced necrosis, and maximum achieved temperature. The non-perfused volume ratio (NPV related to myoma volume) was quantified. The fibroid volume was measured before, 1 month, and 6 months after therapy. Symptoms were quantified using a specific questionnaire (UFS-QoL). RESULTS: In total, 205 TC and 227 FC were applied. The NPV ratio was 23 ± 15 % (2 ­ 55). The TC were slightly smaller than intended (-3.9 ± 52 %; range, -100 ­ 81), while the FC were 20.1 ± 25.3 % bigger (p = 0.02). Feedback mechanism is less diversifying in diameter (p < 0.001). Overall, the FC correlate well with the planned treatment diameter (r = 0.79), other than the TC (r = 0.38). Six months after therapy, the fibroid volume was reduced by 45 ± 21 % (5 ­ 100) (p = 0.001). The symptoms decreased significantly (p = 0.001). No serious adverse events were recorded. CONCLUSION: Use of volumetric sonication leads to homogenous heating and sufficient necrosis. It is a safe and effective therapy for treating symptomatic uterine fibroids. Successful sonication of feedback cells leads to more contiguous necrosis in diameter

[The thickened left ventricle: etiology, differential diagnosis and implications for cardiovascular radiology]. / Der dicke linke Ventrikel: Ursachen und Differenzialdiagnose der linksventrikulären Hypertrophie und Implikationen für die kardiovaskuläre Radiologie.

Hypertrophy of the left ventricular myocardium is a common finding and can be reliably detected by echocardiography, CT and MRI. Common causes include diseases associated with increased cardiac afterload as well as primary and secondary cardiomyopathy. With the opportunity to determine functional parameters and myocardial mass precisely as well as to detect structural changes of the cardiac muscle simultaneously, cardiac MRI is the most precise imaging method for quantifying left ventricular hypertrophy as well as determining the cause and the exact characterization of the myocardial changes. It is mandatory, however, to create a flexible, individually adapted examination protocol. This review presents useful diagnostic algorithms in relation to different underlying pathologies in patients with left ventricular hypertrophy.

[Tumor and pulmonary cysts - Lice, fleas or both?]. / Tumor und Zysten in der Lunge - Läuse, Flöhe oder beides?

The article reports on a 60-year-old female patient with insulin-dependent diabetes who presented with coughing, chest pains and low-grade fever. Auscultation revealed a vesicular breathing noise bilaterally and the laboratory results showed slightly increased infection parameters. The initial diagnostic work-up included chest x-ray and contrast-enhanced computed tomography (CT). The diagnostics resulted in a pulmonary adenocarcinoma with osseous and hepatic metastases. Furthermore, widespread bilateral pulmonary cystic lesions were observed. Regarding the wide spectrum of differential diagnoses and the clinical pattern, the findings have to be regarded as cystic metastases and not as primary cystic lung disease.

[Consensus recommendations of the German Radiology Society (DRG), the German Cardiac Society (DGK) and the German Society for Pediatric Cardiology (DGPK) on the use of cardiac imaging with computed tomography and magnetic resonance imaging]. / Konsensusempfehlungen der DRG/DGK/DGPK zum Einsatz der Herzbildgebung mit Computertomografie und Magnetresonanztomografie.

Cardiac magnetic resonance imaging (MRI) and computed tomography (CT) have been developed rapidly in the last decade. Technical improvements and broad availability of modern CT and MRI scanners have led to an increasing and regular use of both diagnostic methods in clinical routine. Therefore, this German consensus document has been developed in collaboration by the German Cardiac Society, German Radiology Society, and the German Society for Pediatric Cardiology. It is not oriented on modalities and methods, but rather on disease entities. This consensus document deals with coronary artery disease, cardiomyopathies, arrhythmias, valvular diseases, pericardial diseases and structural changes, as well as with congenital heart defects. For different clinical scenarios both imaging modalities CT and MRI are compared and evaluated in the specific context.

[Non-invasive thermoablation of symptomatic uterine fibroids with magnetic resonance-guided high-energy ultrasound]. / Nichtinvasive Thermoablation symptomatischer Uterusmyome mit MR-gesteuertem hochenergetischem Ultraschall.

Uterine fibroids are the most common benign tumors in postmenopausal women which can cause severe symptoms and considerably reduce the quality of life. Patients are requesting minimally invasive, organ-saving therapies increasingly more often and magnetic resonance-guided focused ultrasound is a promising new technology which even surpasses these requirements as it is a totally non-invasive approach. The possibility of real-time temperature mapping allows a safe and precise thermal ablation of uterine fibroids. The rate of adverse events is low and safety and efficiency have been proven in several clinical studies. Further studies will have to be carried out to demonstrate long-term success and comparability to the established therapies and clarify if focused ultrasound is a safe treatment for women with the desire for future pregnancy. The MR-guided focused ultrasound technique is an effective and gentle treatment for uterine fibroids and holds a great potential for further indications.

[Female patient with hematemesis and upper abdominal pain]. / Kontrastverstärkter Ultraschall der Skelettmuskulatur.

A 42-year-old female patient presented with acute pain of the upper abdomen, postprandial vomiting and hematemesis. An operation for gastric banding had been carried out 1 month prior to presentation. The abdominal X-ray and radioscopy revealed a posterior slippage of the gastric fundus following the gastric banding operation.

Myocardial scars are an underestimated cardiovascular burden in patients with internal carotid artery stenosis.

BACKGROUND: Patients with internal carotid artery (ICA) stenosis have an increased incidence of coronary heart disease. Evidence about the incidence of clinically silent myocardial infarction (MI) in these patients is limited. Contrast-enhanced cardiac magnetic resonance (CMR) imaging allows for the detection of minor myocardial damage. OBJECTIVE: We tested whether patients with ICA stenosis exhibit a relevant incidence of silent MI when assessed by CMR. METHODS: In a single-center study, 77 consecutive patients (age 68 +/- 7 years) with suspected ICA stenosis were imaged prospectively with a combined MRI protocol including T(1), T(2), diffusion-weighted imaging, fluid-attenuated inversion recovery, and contrast-enhanced MR angiography (CEMRA) imaging of the brain and a short (11 min) CMR protocol with left ventricular function and late gadolinium enhancement imaging. Blinded to any clinical information, two readers evaluated the cardiac and neuroradiologic examinations. RESULTS: Of 154 imaged ICA, 85 presented with stenosis and 17 were occluded. In 7 patients, the suspected ICA stenosis could not be confirmed by CEMRA. In the remaining 70 patients with ICA stenosis, 34.3% had cerebral lesions (15.7% with a homodynamic pattern,18.6% with territorial infarction). CMR detected MI in 29 (41%) patients, whereas ECG and medical history enabled diagnosis in only 7 (10%) patients. CONCLUSIONS: ICA stenosis patients have a higher incidence of myocardial scars proving silent MI when detected by contrast-enhanced CMR than clinically expected. Whether the presence and extent of silent MIs detected by CMR affect peri-interventional risk and prognosis of ICA stenosis patients remains to be evaluated in a large patient cohort with long-term follow-up.

Comparison of aortic valve area measured by magnetic resonance imaging and dual-source computed tomography.

BACKGROUND: Aortic valve stenosis is the most common type of valve lesion in Europe and North America. Patient treatment is based on disease severity, which is classified by determining the aortic valve area (AVA). PURPOSE: To compare dual-source computed tomography (DSCT) with magnetic resonance (MR) imaging for quantifying AVA. MATERIAL AND METHODS: Thirty-two patients, 28 with normal aortic valve function and four with aortic valve stenosis, who underwent DSCT coronary angiography (Somatom Definition; Siemens, Erlangen, Germany), were included in this study. Retrospective ECG-gated contrast-enhanced DSCT scans with dose-reducing tube current modulation were performed, and data sets were reconstructed in 3% steps of the R-R interval (slice thickness 0.75 mm, increment 0.6 mm). Planimetry of the AVA in systole was assessed on cross-sectional images by multiplanar reformations. Within 48 hours, MR was performed with a 1.5T scanner (Magnetom Sonata; Siemens, Erlangen, Germany) using a balanced steady-state free-precession cine sequence (repetition/echo time 3/1.5 ms, flip angle 60 degrees, spatial resolution 1.4 x 1.4 mm(2)). Cine sequences of the left ventricular outflow tract (LVOT) were obtained in two orthogonal planes, and MR planimetry was performed on cross-sectional images of the aortic valve perpendicular to the LVOT images. RESULTS: AVA assessment by DSCT and MR was feasible in all 32 patients. Mean AVA values determined by DSCT and MR were 4.73+/-1.5 cm(2) and 4.69+/-1.4 cm(2), respectively. A strong positive correlation was found between both imaging modalities (R=0.98, P<0.001). Bland-Altman analysis demonstrated an excellent intermodality agreement, with a slight underestimation of AVA by DSCT. The mean difference was -0.04 cm(2), with a standard deviation of 0.32 cm(2). CONCLUSION: Retrospective ECG-gated contrast-enhanced DSCT with tube current modulation provides an accurate imaging technique for the assessment of the AVA. Further studies are required to determine whether DSCT also allows for AVA quantification in patients with aortic valve stenosis.

[Quantification of microvascular obstruction in acute myocardial infarction using cardiac MRI]. / Kardiale MRT zur Quantifizierung der mikrovaskulären Obstruktion beim akuten Myokardinfarkt.

PURPOSE: Microvascular obstruction (MO) and the extent of infarction are important prognostic factors in acute myocardial infarction. Our study aimed to investigate the effect of the time interval between contrast administration and image acquisition on the quantification of microvascular obstruction and myocardial infarction. MATERIALS AND METHODS: 50 consecutive patients with acute myocardial infarction (40 male, mean age 58.1 +/- 11.7 years) treated by percutaneous coronary revascularization resulting in a grade 3 flow according to the thrombolysis in myocardial infarction flow classification were examined on a 1.5 T MR scanner within the first 5 days after infarction. 2, 5, 10, and 20 minutes after I.V. administration of 0.2 mmol/kg per kg body weight of Gadodiamid (Omniscan), GE Healthcare Buchler, Germany), a single shot IR-SSFP sequence (TR 2.4 ms, TE 1.08 ms, TI 180 - 280 ms, FA 50 degrees) covering the entire left ventricle was acquired. Areas of MO and myocardial infarction were measured for all times after contrast injection (p. i.). RESULTS: MO was detected in 32 of 50 patients two minutes p. i., while 23 patients showed evidence of MO (p = 0.002) 20 min. p. i. In all patients with MO, the extent of MO decreased over time (7.4 +/- 9.0 % of the LV myocardium 2 min. p. i. vs. 2.4 +/- 4.6 % 20 min. p. i. p < 0.0001). The area of myocardial infarction increased from 13.9 +/- 13.5 % 2 min. p. i. to 18.6 +/- 14.2 % 10 min. p. i. (p < 0.0001), and then remained unchanged (18.7 +/- 14.3 % at 20 min. p = 0.57). CONCLUSION: Our study shows that the time delay between contrast media injection and image acquisition has a significant impact on the delimitable extent of MO and infarct size.

Magnetic resonance coronary angiography: comparison between a Gd-BOPTA- and a Gd-DTPA-enhanced spoiled gradient-echo sequence and a non-contrast-enhanced steady-state free-precession sequence.

BACKGROUND: Several studies have demonstrated that the administration of contrast agents is advantageous in magnetic resonance coronary angiography (MRCA). PURPOSE: To compare a non-contrast-enhanced steady-state free-precession (SSFP) with a contrast-enhanced inversion recovery spoiled gradient-echo (IR-GE) sequence using two different contrast agents for MRCA. MATERIAL AND METHODS: Eight healthy volunteers were examined on a 1.5T MR scanner. For non-contrast-enhanced MRCA, a breath-hold three-dimensional (3D) SSFP sequence (repetition/echo time [TR/TE] 3.9/1.7 ms, flip angle [FA] 65 degrees) was used. Contrast-enhanced MRCA was performed repetitively in two imaging sessions over 30 min after injection of 0.2 mmol/kg body weight gadobenate dimeglumine (Gd-BOPTA) or gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) using a breath-hold 3D IR-GE sequence (TR/TE 4.1/1.7 ms, FA 15 degrees). The signal-to-noise ratios (SNR) of the coronary arteries, as well as the contrast-to-noise ratios (CNR) between coronary arteries and perivascular tissue, were calculated for all images. Blood T (1) values were repetitively estimated over 30 min using an SSFP sequence with incrementally increasing inversion times (TR/TE 2.4/1.0 ms, FA 50 degrees). RESULTS: Gd-BOPTA-enhanced images showed significantly (P<0.05) higher SNR and CNR compared to Gd-DTPA-enhanced images for all times after contrast injection (SNR: 1 min post injection [PI] 26.4+/-4.2 vs. 16.2+/-3.1; CNR: 1 min PI 21.4+/-3.7 vs. 13.2+/-2.6). Compared to the SSFP images, the Gd-BOPTA-enhanced images showed higher CNR values for all times after injection (1 min PI 21.4+/-3.7 vs. 13.8+/-5.5; P<0.05), whereas the Gd-DTPA-enhanced images did not (1 min PI 13.2+/-2.6 vs. 13.8+/-5.5; P>0.05). Blood T (1) estimates were not significantly different for either agent 1 min after administration (P>0.05), but they were significantly lower for Gd-BOPTA (P<0.05) from 7 to 25 min after injection. CONCLUSION: Compared to non-contrast-enhanced SSFP images, only Gd-BOPTA-enhanced images show a significantly improved contrast between the coronary arteries and the surrounding tissue.

Mid-term outcome of positron emission tomography/computed tomography-assisted radiofrequency ablation in primary and secondary liver tumours--a single-centre experience.

AIMS: To determine the mid-term results of percutaneous radiofrequency ablation (RFA) of malignant liver tumours when using FDG-positron emission tomography (FDG-PET)/computed tomography for tumour evaluation and follow-up. MATERIALS AND METHODS: Between January 2002 and June 2006, 55 patients (mean age 63 years) with 78 liver lesions (39 colorectal metastases, 39 hepatocellular carcinoma [HCC] nodules) were treated with RFA. All patients received PET/computed tomography before intervention. RFA was performed under computed tomography guidance with conscious sedation. Post-interventional PET/computed tomography was carried out in PET-positive patients 24h after the ablation and was repeated at 1, 3 and 6 months and every 6 months after the intervention. PET-negative patients received contrast-enhanced computed tomography at the same time points. The rate of local tumour progression (LTP) and survival rates were assessed for the whole patient population. RESULTS: The 78 lesions (mean size 2.3 cm, range 0.8-5 cm) were treated with 101 consecutive ablation procedures resulting in a technical success rate of 96%. The mean time of follow-up was 25+/-12 months. Thirty-five of 78 tumours (45%) developed LTP. At the end of follow-up, LTP was found in 22 patients (40%), with intra- and extrahepatic recurrence in 11 patients. Twenty-two patients remained free of hepatic tumours. The 1-, 2- and 3-year survival rates were 85, 74 and 58%, respectively. Tumour entity, lesion size and localisation were significant risk factors for LTP. CONCLUSIONS: Computed tomography-guided RFA of malignant liver tumours is effective, but shows a high rate of LTP. PET/computed tomography supports RFA by early identification of residual tumour or LTP.

["Dead or alive?": how and why myocardial viability imaging by cardiac MRI works]. / "Tot oder lebendig?": Wie und warum myokardiale Vitalitätsdiagnostik mit MRT funktioniert.

Myocardial viability imaging by contrast-enhanced MRI has supported the broad acceptance of cardiac MRI as a valuable clinical tool in cardiology over the last few years. The late enhancement (delayed enhancement, late gadolinium enhancement) technique has emerged as an easy-to-perform and robust method for identifying and quantifying myocardial scars. In the condition of acute myocardial infarction, MRI offers important prognostic information regarding anticipated left ventricular changes ("remodeling") and future cardiac events. In coronary artery disease patients with chronic infarction, the extent of late enhancement reliably predicts the outcome of global and regional left ventricular function after revascularization. In particular, CAD patients with severely impaired left ventricular function benefit from preoperative viability imaging before bypass surgery. The present paper describes the definitions and physiology of viable and non-viable myocardium as well as the pathophysiologic basis of late enhancement. The process from the correct setting of imaging protocols via the interpretation of late enhancement images to the stating of the correct diagnosis and estimation of viability is followed. The background of the successful development of the late enhancement method towards the new reference standard in myocardial viability imaging is described.

[Rapid total body fat measurement by magnetic resonance imaging: quantification and topography]. / Schnelle Ganzkörperfettmessung mittels MRT: Quantifizierung und Topografie.

PURPOSE: To evaluate a rapid and comprehensive MR protocol based on a T1-weighted sequence in conjunction with a rolling table platform for the quantification of total body fat. MATERIALS AND METHODS: 11 healthy volunteers and 50 patients were included in the study. MR data was acquired on a 1.5-T system (Siemens Magnetom Sonata). An axial T1-weighted flash 2D sequence (TR 101, TE 4.7, FA 70, FOV 50 cm, 205 x 256 matrix, slice thickness: 10 mm, 10 mm interslice gap) was used for data acquisition. Patients were placed in a supine position on a rolling table platform capable of acquiring multiple consecutive data sets by pulling the patient through the isocenter of the magnet. Data sets extending from the upper to lower extremities were collected. The images were analyzed with respect to the amount of intraabdominal, subcutaneous and total abdominal fat by semi-automated image segmentation software that employs a contour-following algorithm. RESULTS: The obtained MR images were able to be evaluated for all volunteers and patients. Excellent correlation was found between whole body MRI results in volunteers with DEXA (r (2) = 0.95) and bioimpedance (r (2) = 0.89) measurements, while the correlation coefficient was 0.66 between MRI and BMI, indicating only moderate reliability of the BMI method. Variations in patients with respect to the amount of total, subcutaneous, and intraabdominal adipose tissue was not related to standard anthropometric measurements and metabolic lipid profiles (r (2) = 0,001 to 0.48). The results showed that there was a significant variation in intraabdominal adipose tissue which could not be predicted from the total body fat (r (2) = 0.14) or subcutaneous adipose tissue (r (2) = 0.04). Although no significant differences in BMI could be found between females and males (p = 0.26), females showed significantly higher total and subcutaneous abdominal adipose tissue (p < 0.05). CONCLUSION: This MR protocol can be used for the rapid and non-invasive quantification of body fat. The missing relationship between serum lipids and body fat masses suggests that the latter is an additional and independent hazard factor. Variations in body fat distribution, e. g. relationship between subcutaneous and intraabdominal fat, can be comprehensively assessed.