Open Field Exercise Testing in Pediatric Congenital Heart Disease Patients: A Subsumption of Cardiovascular Parameters.

Heart failure is a common phenomenon in congenital heart disease patients. Cardiopulmonary exercise testing is used for a reliable assessment of heart failure but is still challenging, especially for young children. Implementing mobile cardiopulmonary exercise testing (CPET) can close that diagnostic gap. While average values for healthy children have already been published, this study aims to describe typical ranges of cardiovascular performance parameters of young children with congenital heart disease performing an 8-min running cardiopulmonary exercise test. Children aged 4-8 years with common congenital heart defects after corrective surgery (Tetralogy of Fallot; transposition of the great arteries and univentricular hearts after palliation) were included. The outdoor running protocol consisted of slow walking, slow jogging, fast jogging, and maximum speed running. Each exercise was performed for 2 min, except the last, in which children were instructed to keep up maximal speed as long as possible. A total of 78 children (45 male/33 female, mean age 6,24) with congenital heart disease participated in the study, of which 97% completed the CPET successfully. A detailed description of participating patients, including data on cardiac function and subjective fitness levels, is given to help physicians use this method to classify their patients. This study presents a typical range for cardiovascular performance parameters in a population of 4-8-year-old children with congenital heart disease tested in a newly developed outdoor running protocol for CPET.

Accuracy of the Apple Watch iECG in Children With and Without Congenital Heart Disease.

The development of smart technologies paves the way for new diagnostic modalities. The Apple Watch provides an FDA approved iECG function for users from 22 years of age. Yet, there are currently no data on the accuracy of the Apple Watch iECG in children. While arrhythmias are a frequent phenomenon in children, especially those with congenital heart disease, the increasing spread of smart watches provides the possibility to use a smart watch as mobile event recorder in case of suspected arrhythmia. This may help to provide valuable information to the treating physician, without having the patient to come to the hospital. Necessary treatment adjustments might be provided without timely delay. The aim of this study was therefore to evaluate the agreement of measured values of rate, interval, and amplitude with those obtained by a diagnostic quality ECG recording to an Apple Watch iECG in children with and without congenital heart disease. In this prospective, single-arm study, consecutive patients aged 0-16 years presenting to the Heart Center Leipzig, Department for pediatric cardiology were included. After obtaining informed consent from participants' parents, a 12-lead ECG and an iECG using an Apple Watch were performed. Cardiac rhythm was classified, amplitudes and timing intervals were measured and analyzed in iECG and 12-lead ECG for comparability. These measurements were performed blinded to the patients' history by two experienced pediatric cardiologists. Patient demographic data, medical and cardiac history were assessed. 215 children between 0 and 16 years were enrolled. Comparison of amplitudes and timing intervals between ECG and iECG showed excellent correlation (K > 0.7, p < 0.01) in all parameters except for the p-waves. Automatic rhythm classification was inferior to manual interpretation of ECG / iECG, while iECG interpretation was reliable in 94.86% of cases. The study demonstrates equal quality of the Apple Watch derived iECG compared to a lead I in 12-lead ECG in children of all age groups and independent from cardiac anatomy.

The Fontan and the Sea: First-in-Man Data on Swimming and Diving Physiology in Fontan Patients.

While swimming represents a popular recreational activity, the immersion of the human body into the water requires a complex physiologic adaption of the whole cardiopulmonary and circulatory system. While this sport is regarded as beneficial, especially in cardiovascular patients, current guidelines hypothesized a possible hazardous effect of swimming and especially diving in patients with univentricular hearts after Fontan palliation. Yet, actual data to underline or contradict these assumptions are lacking. Therefore, this study aimed to conduct a first feasibility study for the evaluation of these effects on Fontan physiology and elucidate the gap of evidence currently preventing patients after Fontan palliation from being restricted from swimming or diving on doctoral advice. Patients recruited from the Heart Center Leipzig, Department of pediatric cardiology, underwent spiroergometry treadmill testing followed by a spiroergometry swimming stress test in a counter current pool. Physiologic data were recorded. A short apnea diving test was performed. The current study found similar physiologic reactions comparing treadmill and swimming exercise stress testing. Heart rate response and oxygen uptake were comparable on land and in the water. This study presents the first-in-man data on swimming and diving in Fontan patients. In this small study cohort of three Fontan patients, there were no adverse events triggered by swimming and breath-hold diving seen. Basically, the physiologic response to exercise was comparable on land and in the water.

Assessment of the distal anastomosis of coronary artery bypass grafts with a 2D T2-weighted turbo spin echo sequence and correlation to conventional coronary angiography.

OBJECTIVE: The aim of the study was to evaluate the patency of the distal anastomoses of coronary artery bypass grafts and to detect graft stenoses and occlusions with a magnetic resonance (MR) spin echo sequence. PATIENTS AND METHODS: One hundred and eighty-five patients with 481 distal anastomoses were examined with a 1.5 T MR scanner and coronary angiography. A 2-dimensional T2-weighted breath-hold half-Fourier acquisition single-shot turbo spin echo sequence (Haste) was performed. All images were evaluated independently by a radiologist and cardiologist and compared to the conventional coronary angiography. The observers were blinded to the coronary angiography findings, but informed in regard to the surgical graft anastomosis. RESULTS: With the Haste sequence, 76% of the distal anastomoses were recognized (368/481). Forty-five of 52 (87%) stenoses and all occlusions were identified. The sensitivity and specificity for the evaluation of the distal anastomosis with the spin echo sequence was 87% and 96%. Twenty-four percent of the distal anastomoses were not identified due to a poor image quality or motion artefacts. CONCLUSION: Using the Haste sequence, a reliable assessment of graft patency of the distal anastomosis is possible. Further improvements of the spatial resolution and the image quality are necessary to recommend this MR technique for routine clinical use.

[Comparison of contrast-enhanced MR angiography of the aortoiliac vessels using a 1.0 molar contrast agent at 1.0 T with intra-arterial digital subtraction angiography]. / Ergebnisse der kontrastverstärkten MR-Angiographie der aortoiliakalen Gefässe mit einem 1-molaren Kontrastmittel bei 1,0 T: Vergleich zur i. a. DSA.

PURPOSE: To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) using a 1.0 molar contrast agent at 1.0 T for the diagnosis of abdominal aortic aneurysms and stenoses of renal or iliac arteries in comparison to intraarterial digital subtraction angiography (DSA). MATERIALS AND METHODS: A total of 19 patients with the suspicion of abdominal aortic aneurysm or stenosis of renal or iliac arteries were examined with CE-MRA at 1.0 T. Intra-arterial DSA served as reference in all cases. After test bolus tracking, 10 or 8 ml of the 1.0 molar contrast agent Gadobutrol corresponding to a dose of 0.1 - 0.15 mmol/kg bw were injected and imaging performed using a FLASH-3D sequence. To evaluate the interobserver-variability, the blinded images were analyzed by two radiologists. Besides the rating of overall image quality on a 4-point-scale, the images were evaluated for aneurysms and arteriosclerotic lesions with a stenosis of < 50 % or > 50 % or occlusion. RESULTS: A total of 144 segments were analyzed. The mean value of the CE-MRA image quality was 3.4 on a 4-point-scale. The sensitivity of CE-MRA in depicting relevant pathological findings was 96 % and the specificity 99 %. The positive predictive value was 96 % and the negative predictive value 99 %. Inter-observer variability was low with a kappa value of 0.82. CONCLUSION: CE-MRA using a 1.0 molar contrast agent at 1.0 T enables an excellent diagnosis or exclusion of pathologies of the aortoiliac vessels.

[Paraneoplastic limbic encephalitis in small cell lung carcinoma]. / Paraneoplastische limbische Enzephalitis bei kleinzelligem Bronchialkarzinom.

We report about a 63-year-old male patient who complained of a recent onset of confusion. A mediastinal mass had been detected in his chest X-ray three days before admission to our clinic. Surprisingly, a CT scan of the brain revealed no signs of cerebral masses or oedema. MRI demonstrated bright hyperintens signals in the medial aspect of both temporal lobes. Biopsy by mediastinoscopy showed small cell lung carcinoma (SCLC). No distant metastases were found by staging procedures. Cerebrospinal fluid and serum contained antineuronal antibodies (anti-Hu). The combination of symptoms, MRI findings and paraneoplastic antibodies established the diagnosis of paraneoplastic limbic encephalitis in a patient with SCLC. Chemotherapy combined with immunosuppression by corticosteroids was started immediately. The primary tumour responded to therapy but improvement of cerebral symptoms was unsatisfactory. Severe memory loss and personality changes remained unchanged while there was a slight improvement in confusion and hallucinations.

Late improvement of regional wall motion after the subacute phase of myocardial infarction treated by acute PTCA in a 6-month follow-up.

BACKGROUND: The aim of this follow-up study was to investigate the late effects of acute coronary angioplasty (PTCA) on regional wall motion after the subacute phase of myocardial infarction (MI). METHODS AND RESULTS: Seventeen patients were investigated initially at a median of 11 days and again at 6 months after acute PTCA for myocardial infarction (< 8 hours after onset of symptoms) by cardiac magnetic resonance imaging. Corresponding short-axis slices encompassing the left ventricle (LV) were acquired using a standard cine MR for regional wall motion analysis and using delayed contrast enhanced magnetic resonance imaging (ceMRI) for infarct size quantification. The infarct size was similar in the subacute phase and the 6 month follow-up (20.8 and 21.9%, respectively; n.s.). Regional wall motion improved significantly in the area of hyperenhancement [percentage wall thickening (PWT) 21.9% and 37.9%, p < 0.05] in contrast to remote normal myocardium (46.4% and 38.4%; n.s.). Regional wall motion was significantly poorer in transmural compared with nontransmural MI in the subacute stage, and a late improvement could only be observed in transmural MI. CONCLUSION: Transmural areas of hyperenhancement displayed significant late long-term improvement of regional wall motion after acute PTCA, possibly related to prolonged stunning compared with nontransmural areas.

[Indirect MR-arthrography in the follow up of autologous osteochondral transplantation]. / Indirekte MR-Arthrographie zur Verlaufskontrolle nach autologer osteochondraler Transplantation.

PURPOSE: To evaluate the spectrum of findings in indirect MR-arthrography following autologous osteochondral transplantation. PATIENTS AND METHODS: 10 patients with autogenous osteochondral homografts underwent indirect MR-arthrography at three, 6 and 12 months postoperatively. The MR protocol at 1.5 T comprised unenhanced imagings with PD- and T2 -weighted TSE- sequences with and without fat-suppression as well as T1 -weighted fat-suppressed SE-sequences before and after i.v. contrast administration and after active joint exercise. Image analysis was done by two radiologists in conference and comprised the evaluation of signal intensity (Sl) and integrity of the osseous plug and the cartilage surface, as well as the presence of joint effusion or bone marrow edema. RESULTS: At three months, all cases demonstrated a significant bone marrow edema at the recipient and donor site that corresponded to a significant enhancement after i.v. contrast administration. The interface between the transplant and the normal bone showed an increased Sl at three and 6 months in T2 -weighted images as well as in indirect MR-arthrography. The marrow signal normalized in most cases after 6 to 12 months, indicating vitality and healing of the transplanted osteochondral graft. The Sl of the interface decreased in the same period, demonstrating the stability of the homograft at the recipient site. The osteochondral plugs were well-seated in 9/10 cases. Indirect MR-arthrography was superior to unenhanced imaging in the assessment of the cartilage surface. Cartilage coverage was complete in every case. The transplanted hyaline cartilage as well as the original cartilage showed a significant increase of the Sl in indirect MR-arthrography, that did not change in follow up studies. There were no pathological alterations of signal and thickness alterations of the transplanted cartilage in follow up investigations. CONCLUSION: Indirect MR-arthrography is a useful diagnostic tool following autologous osteochondral transplantation. Assessment of transplant vitality, osseous fixation and stability is possible.

[Preliminary results of coronary artery examination using a 3D-navigator sequence on a high performance MR system]. / Erfahrungen mit einer 3D-Navigatorsequenz zur Koronargefässdarstellung an einem Hochleistungs-MR-System.

PURPOSE: To evaluate MR coronary angiography using a three-dimensional navigator echo sequence on a MR scanner with a high performance gradient system. MATERIAL AND METHODS: Five healthy volunteers were examined with a 1.5 Tesla MR system, using a high performance prototype gradient system (peak amplitude 50 mT/m, rising time 600 mus). For imaging, a navigated gradient-echo pulse sequence with an in-plane resolution between 0.63 x 0.63 and 0.78 x 0.78 mm2 was used. Per patient two overlapping slabs were acquired. The number of visualized coronary artery segments was estimated (AHA classification). In addition, signal-to-noise measurements were performed in the ascending aorta at the level of the proximal right and left coronary arteries. RESULTS: In all volunteers the left main, the right coronary artery up to segment 3, the LAD up to segment 8 and the RCX with segment 11 and 13 were clearly visualized. The average signal-to-noise value at the level of the right coronary artery was 11.4 +/- 5.0, at the level of the left coronary artery 12.3 +/- 4.5. One volunteer was measured with an in-place resolution of 0.63 x 0.63 mm2. This resulted in a too low signal-to-noise ratio so that an adequate assessment of coronary arteries was no longer possible. CONCLUSION: 3D-MR coronary angiography using the navigator technique is limited by the signal-to-noise ratio.

Non-invasive magnetic resonance imaging of coronary bypass grafts. comparison of the haste- and navigator techniques with conventional coronary angiography.

OBJECTIVE: The aim was the study was to evaluate the patency of coronary artery bypass grafts with the 3D Navigator and the Haste magnetic resonance imaging techniques. MATERIAL AND METHODS: Thirty-four patients with 82 grafts (18 internal mammarian artery and 64 saphenous venous grafts) were examined at 1.5 T using a phased arrray body coil. A 2D T-2 weighted turbo spin echo sequence (Haste) and a 3D-angiography sequence in navigator technique were used. Reference method was the conventional coronary angiography that was performed within 7 days. RESULTS: With the HASTE sequence 54 of 56 patent and 12 of the 16 occluded grafts were recognized, the sensitivity and specificity was 96 and 75%. The distal anastomosis could be assessed in 28 of 76 cases. With the Haste sequence 54 of the 56 patent and 12 of the 14 occluded grafts were detected correctly. Eight patent and two occluded grafts were judged as not assessable. The sensitivity and specificity was 96 and 85%. Sixty-six percent (50/76) of the distal anastomosis were identified correctly. With both sequences none of the bypass stenosis could be detected. CONCLUSIONS: The patency of coronary bypass grafts can be evaluated noninvasively with a sensitivity of 96% and a specificity of 76%. No inference can be made with respect to the nature of bypass graft stenosis. Better results can be expected with the development of a blood pool contrast medium, an improvement of the spatial resolution and in the combination of flow measurements.

[Evaluation of left ventricular aneurysms before and after surgery using Cine-MRI]. / Prä- und postoperative Evaluation von linksventrikulären Herzspitzenaneurysmen mittels Cine-MRT.

PURPOSE: To demonstrate the usefulness of cine-MRI for the evaluation of apical left ventricular aneurysms (ALVA) and for prediction of the surgical outcome. MATERIALS AND METHODS: We investigated 28 patients with ALVA, 13 of them additionally after aneurysmectomy at 1.5 T; 15 healthy volunteers served as normal controls. For cine-MRI k-space segmented Fl-2D-GE sequences were used. Analysis comprised the calculation of cardiac volume indices, cardiac function, and percentual myocardial thickening (PMT). For prediction of surgical results we divided left ventricle into an aneurysmatic and a non-aneurysmatic part. The non-aneurysmatic part was assumed as the left ventricle after surgical remodelling. RESULTS: Enddiastolic and endsystolic volume indices (EDVIs and LV-ESVIs) were higher in patients with ALVA (123.7 +/- 30.2 ml/m(2), 94.3 +/- 32.5 ml/m(2), respectively) than in volunteers (79.1 +/- 13.9 ml/m(2), 25.5 +/- 5.1 ml/m(2), respectively) (p < 0.001). Stroke volume index (SVIs), cardiac index (CIs) and ejection fraction (EFs) were significantly lower in patients (30.4 +/- 9.1 vs. 54.2 +/- 0.2 ml/beat/m(2); 2.2 +/- 0.8 vs. 3.9 +/- 0.9 l/min/m(2), 26.0 +/- 9.7 vs. 67.9 +/- 4.5 %, respectively) (p < 0.001). There was a significant decrease of LV-EDVIs and LV-ESVIs (102.8 +/- 30.3 ml/m(2), 66.3 +/- 28.0 ml/m(2), respectively) (p = 0,002, p < 0.001, respectively), no change of SVIs (36.4 +/- 6.0 ml/beat/m(2)) (p > 0.05) and a significant increase of CIs and EFs (3.0 +/- 0.6 l/min/m(2), 37.91 +/- 10.15 %, respectively) (p < 0.001) after surgery. We found a good correlation between the preoperatively calculated (32.6 +/- 10.1 %) and the measured EF after surgery (37.9 +/- 9.8 %) (r = 0.70; p = 0.035). PMT was significantly lower in patients than in volunteers (median 11.9 +/- 10.7 vs. 70.2 +/- 13.9 %; p < 0.001), especially in the aneurysmatic parts of left ventricle (median - 6.8 %; p < 0.001). CONCLUSION: Cine-MRI offers accurate evaluation of ALVA and enables preoperative estimation of left-ventricular volumes after surgery.

Contrast-enhanced three-dimensional MR angiography of the thoracic aorta: experiences after 118 examinations with a standard dose contrast administration and different injection protocols.

The aim of this study was to test three injection protocols for contrast-enhanced magnetic resonance angiography (MRA) of the thoracic aorta with a standard-dose application. Ninety-three patients with a total of 118 examinations underwent MRA of the thoracic aorta at 1.5 T. There were three injection protocols: in 24 cases, no test bolus was performed and contrast was injected manually; in 14 cases, contrast was injected manually after a test bolus; and in 80 cases, a MR-compatible injector was used after a timing examination. All patients received 20 ml of Gd-DTPA. Quantitative signal-to-noise (SNR) measurements were obtained at different locations in the thoracic aorta, the pulmonary arteries, and the superior vena cava. Two readers in conference retrospectively evaluated each examination with respect to overall image quality and quality of bolus timing. Bolus timing was considered optimal in 70 cases, and either too early or too late in 11 cases. In 37 examinations the bolus was broadened. The SNR measurements of the thoracic aorta revealed that examinations after bolus testing were significantly superior to examinations without a test bolus (p < 0.001). Signal intensity ratios of the aorta and the pulmonary trunk were significantly higher in examinations with an optimal contrast timing (p < 0.001). Magnetic resonance angiograms of the thoracic aorta with a timing run are significantly superior to non-timed examinations with respect to image quality and SNRs. The administration of 20 ml of Gd-DTPA is sufficient for adult patients.

[MRI in chronic epicondylitis humeri radialis using 1.0 T equipment--contrast medium administration necessary?]. / MRT bei chronischer Epicondylitis humeri radialis an einem 1.0 T-Gerät--Kontrastmittelgabe notwendig?

PURPOSE: Evaluation of the diagnostic value and confidence of contrast-enhanced MR imaging in patients with lateral epicondylitis in comparison to clinical diagnosis. MATERIAL AND METHODS: 42 consecutive patients with clinically proven chronic lateral epicondylitis and 10 elbow joints of healthy controls have been examined on a 1.0 T MR-unit. Criteria for inclusion in the prospective study were: persistent pain and a failed conservative therapy. The MR protocol included STIR sequence, a native, T2-weighted, fat-suppressed TSE sequence, and a Flash-2-D sequence. Also, fat-suppressed, T1-weighted SE sequences before and after administration of Gd-DTPA contrast media have been recorded. RESULTS: In 39/42 patients the STIR sequence showed an increased SI of the common extensor tendon. Increased MR signal of the lateral collateral ligament combined with a thickening and a partial rupture or a full thickness tear have been observed in 15/42 cases. A bone marrow edema at the lateral epicondilus was noticed in 6 of the studied patients and a joint effusion in 18/42 patients. After administration of contrast media we noticed an average increase of SI by about 150%. However, enhanced MR imaging did not provide additional information. CONCLUSION: In MR imaging of chronic epicondylitis administration of gadolinium-DTPA does not provide additional information.

[Contrast-enhanced three-dimensional MR angiography of the carotid artery at 1.0 Tesla compared to i.a. DSA: is the method suitable for the diagnosis of carotid stenosis?]. / Kontrastverstärkte dreidimensionale MR-Angiographie der A. carotis bei 1,0 Tesla im Vergleich zur i.a. DSA--ist die Methode für die Diagnostik von Karotisstenosen geeignet?

PURPOSE: To evaluate the efficacy of three-dimensional, contrast-enhanced magnetic resonance angiography (CE-MRA) of the carotid artery with a 1.0 T system in comparison to intra-arterial conventional angiography (i.a.CA) for the assessment of carotid artery disease. METHOD: 55 patients with suspected stenosis of the carotid artery were examined with a 3 D-CE gradient-echo sequence on a 1.0 T scanner (TR/TE = 6.2/2.2 ms) and a selective DSA i.a. angiography. Image quality was evaluated by estimating the arterial contrast and venous enhancement. Morphological pathologies were registered for all arteries, stenoses of the internal carotid artery were graded by applying the NASCET criteria. RESULTS: Sensitivity and specificity of MRA in detecting high-grade stenosis (> or = 70%) and occlusion of the extracranial internal carotid artery were 97.7 and 94.0%. Therapeutic relevant misinterpretations were mostly based on overestimating the stenoses. CONCLUSION: The applied CE-MRA technique with a 1.0 T system is suitable for the assessment of carotid artery stenoses. In case of a therapeutically relevant stenosis revealed by MRA, however, verification of the diagnosis by i.a. CA is recommended.

In vitro investigation of prosthetic heart valves in magnetic resonance imaging: evaluation of potential hazards.

BACKGROUND AND AIM OF THE STUDY: Magnetic resonance (MR) imaging is used in an increasing number of patients, and not only after cardiac valve replacement. However, ferromagnetic biomedical implants are often considered a contraindication for MR imaging because of the potential hazards with respect to their movement, dislodgement, or heating effects during the procedure. The purpose of this study was to assess ferromagnetism, attraction forces, heating effects, and artifacts associated with prosthetic heart valve implants. METHODS: Seventeen common heart valve prostheses (12 mechanical, five biological) were examined in vitro using a high-field-strength 1.5 Tesla (T) MR system. Attractive forces, temperature changes and the amount of artifacts were assessed by applying turbo-spin and gradient-echo sequences. RESULTS: The maximal calculated corresponding ferromagnetic force was (0.22 x 10(-3) N) in the static magnetic field. The temperature changes ranged from 0 to 0.5 degrees C maximum. Artifacts produced by the presence of the heart valve prostheses were less evident using a spin-echo sequence than a gradient-echo sequence. CONCLUSION: MR imaging exerted no significant force on the examined heart valve prostheses, and did not result in significant biological relevant temperature increase. None of the associated artifacts is considered to pose a substantial risk on MR imaging. MR procedures performed with a 1.5 T MR system can be applied safely in patients with heart valve prostheses evaluated in this study.

[Perfusion MR imaging of the heart with TrueFISP]. / MR-Perfusionsbildgebung des Herzens mit TrueFISP.

OBJECTIVE: Development and test of a saturation-recovery TrueFISP (SR-Trufi) pulse sequence for myocardial perfusion MR imaging (MRI) using improved gradient hardware. MATERIAL AND METHODS: Measurements were performed on a 1.5 T scanner with prototype gradients (50 mT/m, minimum rise time 300 microseconds). T1-weighted first-pass MRI of Gd-DTPA (0.025 mumol/kg) kinetics in the myocardium was performed using an SR-Trufi pulse sequence (TR/TE/alpha = 2.6 ms/1.4 ms/55 degrees) with a saturation preparation of TD = 30 ms before the TrueFISP readout. Measurements were performed in volunteers (n = 4) and in a pig model of chronic ischemia (n = 1). RESULTS: In phantoms, the signal intensity was linear with contrast concentration up to 0.9 mmol/kg Gd-DTPA. MR images obtained with SR-Trufi had a good image quality and high spatial resolution of 2.1 mm x 2.1 mm. Differences of the contrast agent's kinetics between a subendocardial perfusion deficit and neighboring myocardium were well visible on both MR images and signal-time curves derived from the region-of-interest analysis. CONCLUSION: SR-Trufi appears to be an interesting new technique for the assessment of myocardial microcirculation using dedicated cardiovascular MR systems.

[MR angiography and flow measurement in coronary arteries and coronary bypass grafts]. / MR-Angiographie und Flussmessung in Koronararterien und koronaren Bypassgefässen.

Better MR image quality of coronary arteries and coronary grafts is the product of increased spatial and temporal resolution. Breathing artifacts could be reduced by implementing breath-holding and navigator techniques. With these developments normal coronary arteries can often be imaged reliably. Several trials have been performed in order to test the reliability of MR angiography to detect coronary artery stenosis. But up to now, sensitivity and specificity have proven to be too low to introduce these techniques in clinical routine. The patency of coronary grafts can be detected reliably using different MR techniques. Coronary flow reserve can be measured using the MR phase contrast technique. This noninvasive approach was tested in diseased coronary arteries and in graft stenoses. A reduced MR coronary flow reserve corresponded to reduced flow reserve measured invasively. Measurement of MR flow reserve in normal and diseased coronary grafts revealed significant differences (3.3 +/- 0.4 vs. 1.3 +/- 0.2).

Hydro-MRI in Crohn's disease: appraisal of disease activity.

RATIONALE AND OBJECTIVES: To appraise the value of hydro-MRI in the assessment of activity in Crohn's disease. METHODS: After bowel opacification with 1000 mL of an orally administered 2.5% mannitol solution was achieved, axial and coronal breath-hold sequences (T2-weighted half-Fourier acquisition single-shot turbo spin-echo sequences with or without fat saturation, dynamic T1-weighted fast low-angle shot sequences, and contrast-enhanced T1-weighted fast low-angle shot with fat saturation sequences) were acquired in 82 patients with proved Crohn's disease at 1.0 T. Enhancement of the bowel wall was correlated with other MRI findings, with the Crohn's disease activity index (CDAI), and with levels of C-reactive protein (CRP). RESULTS: In Crohn's disease, contrast enhancement of the affected bowel wall was markedly increased in comparison with the normal bowel wall (+80% +/- 22% versus +43% +/- 12%; P = 3 x 10(-15)). Positive correlations could be established between the increase in bowel wall enhancement and many other MRI findings. Between the increase in bowel wall enhancement and the CDAI, only a poor correlation was found (r = 0.25, P = 0.02). There was no statistical correlation between the increase in bowel wall enhancement and CRP. CONCLUSIONS: Hydro-MRI seems to be superior to the CDAI and CRP for the registration of Crohn's disease activity. In particular, differentiation between an active and an inactive (scarred) stenosis, which is crucial for the choice of therapeutic procedures, seems to be more reliable by the interpretation of several morphological and functional parameters on hydro-MRI than by the use of CDAI and CRP.

[Low-field MRI of the ankle joint: initial experience in children and adolescents using an open 0.2 T MR-system]. / Niederfeld-MRT des Sprunggelenkes--Erste Erfahrungen bei Kindern und Jugendlichen an einem offenen 0,2 T MR-System.

PURPOSE: To evaluate the feasibility and diagnostic confidence of MRI with an open low field System (Magnetom open, Siemens, Germany) in children with predominantly traumatic disorders. MATERIAL AND METHODS: Conventional X-rays and MRI examinations have been evaluated in 55 children. MRI was performed at an open 0.2 T MR-unit. The study protocol comprised coronal STIR-sequence, an angulated T2 weighted TSE-sequence and T1 weighted SE-sequence. RESULTS: MRI showed ligamental rupture in 33/50 (60%) cases. Injuries of the ATFL were most frequent (27/33); osseous ligamental tears occurred in approx. 50% of all cases. Fractures of the distal tibia and fibula were diagnosed in 28/55 children. 15/28 cases showed an involvement of the epiphysis. We found occult fractures in 11/28 children. Fractures, diagnosed by conventional x-rays, were excluded in 6 cases. Therapy changed in 35/55 patients on the basis of MRI-findings. CONCLUSION: Low-field MRI of the ankle joint in children and adolescents is able to show numerous pathological conditions. We recommend low-field MRI of the ankle in children with persistent or unclear pain of the ankle joint and inconspicuous conventional x-ray.