Evaluation of methods for MR imaging of human right ventricular heart volumes and mass.

PURPOSE: To assess the utility of two different imaging directions in the evaluation of human right ventricular (RV) heart volumes and mass with MR imaging; to compare breath-hold vs. non-breath-hold imaging in volume analysis; and to compare turbo inversion recovery imaging (TIR) with gradient echo imaging in RV mass measurement. MATERIAL AND METHODS: We examined 12 healthy volunteers (age 27-59 years). Breath-hold gradient echo MR imaging was performed in two imaging planes: 1) perpendicular to the RV inflow tract (RVIT view), and 2) in the transaxial view (TA view). The imaging was repeated in the TA view while the subjects were breathing freely. To analyze RV mass using TIR images, the RV was again imaged at end-diastole using the two views. The RV end-diastolic cavity (RVEDV) and muscle volume as well as end-systolic cavity volume (RVESV) were determined with the method of discs. All measurements were done blindly twice to assess repeatability of image analysis. To assess reproducibility of the measurements, 6 of the subjects were imaged twice at an interval of 5-9 weeks. RESULTS: RVEDV averaged 133.2 ml, RVESV 61.5 ml and the RVmass 46.2 g in the RVIT view and 119.9 ml, 56.9 ml and 38.3 g in the TA view, respectively. The volumes obtained with breath-holding were slightly but not significantly smaller than the volumes obtained during normal breathing. There were no marked differences in the RV muscle mass obtained with gradient echo imaging compared to TIR imaging in either views. Repeatability of volume analysis was better in TA than RVIT view: the mean differences were 0.7 +/- 4.0 ml and - 5.4 +/- 14.0 ml in end-diastole and 1.6 +/- 3.1 ml and - 1.5 +/- 13.9 ml in end-systole, respectively. Repeatability of mass analysis was good in both TIR and cine images in the RVIT view but slightly better in TIR images: - 0.5 +/ -2.4 g compared to 0.8 +/- 2.9 g in cine images. Reproducibility of imaging was good, mean differences for RVEDV and RVESV were -1.0 +/- 4.8 ml and -0.8 +/- 2.8 ml, respectively. Mean difference for RVmass was -0.9 +/- 2.6 g. CONCLUSION: The present study suggests that gradient echo MR imaging is well applicable to RV volume and mass measurements. The best imaging plane for volumetric analysis seems to be the TA plane and there was no significant difference between breath-hold and conventional imaging. To assess RV mass, we recommend RVIT view; the TIR sequence quickly produced images of better quality compared to gradient echo images but no significant difference between masses was found and repeatability of analysis was equally good with both methods.

Magnetic resonance imaging angiography in patency evaluation of bronchial artery revascularization grafts.

In this report we present our experience of non-invasive magnetic resonance imaging (MR) angiography and selective catheter angiography in assessing the patency of bronchial artery revascularization grafts after an en bloc double-lung and heart-lung transplantation. We studied 8 patients who had undergone pulmonary transplantation with direct bronchial artery revascularization. Catheter angiography was performed 10 days to 63 months postoperatively. MR angiography was performed within 24 h of the catheter procedure and the results were compared with the findings from catheter angiography. Catheter angiography showed the bronchial revascularization graft to be patent in 6 patients and occluded in 2. At MR angiography, the patency of bronchial artery revascularization grafts was reliably identified in 7 of the 8 patients. One patient had inadequate image quality because of void artefacts caused by haemostatic clips. It is concluded that MR angiography is a reliable method for assessing the patency of bronchial artery revascularization grafts.

Bronchial artery revascularization improves tracheal anastomotic healing after lung transplantation.

The study aimed to clarify the role of direct bronchial artery revascularization (BAR) after en bloc double-lung (DLT) and heart-lung transplantation (HLT). Group I comprised eight patients with en bloc DLT or HLT and successful BAR, while group II included 14 DLT or HLT cases without BAR or with failed BAR. From these groups, 2 subgroups were extracted: group III, including 6 cases of en bloc DLT with successful BAR and group IV 10 HLT cases without or with failed BAR. Airway healing was evaluated at bronchoscopy and patency of BAR with angiography. Pulmonary viral, bacterial and fungal infections, rejections and bronchiolitis obliterans syndrome (BOS) were registered. Tracheal healing at 2 weeks and 3 months was better in group I than in group 1 (p = 0.003 and p = 0.05, respectively). Compared with group IV, tracheal anastomotic healing at 2 weeks was better in group III (p = 0.007) and tended to be better also after 3 months (p = 0.07). The incidence of infections, rejection or BOS did not differ between groups I and II. BAR thus improved healing of tracheal anastomosis.

Ultrasonography in the quantification of arterial involvement in Takayasu's arteritis.

OBJECTIVE: To evaluate the accuracy of ultrasonography (US) in the detection and quantification of arterial involvement in Takayasu's arteritis (TA). METHODS: The common carotid and subclavian arteries, and the abdominal aorta of 15 patients with TA were studied by Color Doppler (CD) US and Doppler spectral analysis and compared with angiography. RESULTS: The mean difference (+/-SD) between the percent luminal stenoses measured at angiography and by CD US was 2.0+/-10.3% for the common carotid artery, 4.0+/-23.6% for the subclavian artery and -1.3+/-16.8% for the abdominal aorta. The differences were not statistically significant. However, the agreement of the methods was less than satisfactory as shown by the wide standard deviations. CONCLUSIONS: More efforts are needed to improve the less than optimal agreement of US with angiography regarding the severity of individual stenoses. The technique performs best in the study of carotid arteries.

MR gradient echo volumetric analysis of human cardiac casts: focus on the right ventricle.

PURPOSE: Our goal was to assess the utility of different imaging directions in volumetric studies of the heart with MRI, in particular to identify the optimal imaging plane for studies of the right ventricle. METHOD: We examined 12 sets of human four-chamber cadaveric cardiac casts. Gradient echo MRI was performed in four imaging planes: (a) perpendicular to the right ventricular inflow tract; (b) perpendicular to the right ventricular outflow tract; (c) in the left ventricular short axis view; and (d) in the axial view. The volumes of the right ventricle and other cardiac cavities were determined with the method of discs. The true cast volumes were measured with the water displacement technique. The agreement between true and measured volumes and the repeatability of image analysis were determined using the Bland-Altman method. RESULTS: There were no statistically significant differences between the measured and true right ventricular volumes irrespective of the imaging plane. The axial plane gave the smallest mean absolute difference from the true right ventricular volume (3.2 +/-2.2 ml) and also the best repeatability of volume analysis (0.2+/-1.6 ml). However, the other imaging planes performed nearly as well, and the differences across the planes were not statistically significant (p > 0.05). Also, in studies of the left ventricle and left and right atrium, the axial view appeared to give the best results, but differences across the imaging planes remained small. CONCLUSION: The present studies of human cardiac casts suggest that gradient echo MRI is well applicable to right ventricular volume measurements. Imaging the right ventricle in axial planes covering the entire heart gives good agreement with true right ventricular volumes and excellent analysis reproducibility. However, other imaging directions perform nearly as well, and thus selection of the imaging plane may not be of major importance to the accuracy of cardiac volume measurements with MR.

Graft patency evaluation with colour-Doppler ultrasonography after bypass surgery in Takayasu's arteritis: a direct colour-flow lumen imaging method.

OBJECTIVES: To assess the feasibility and potential diagnostic usefulness of colour-Doppler flow imaging (CDFI) to detect complications of supra-aortic vascular bypass grafts in Takayasu's arteritis (TA). DESIGN: A prospective study. MATERIALS: Nine supra-aortic grafts in six patients with Takayasu's arteritis. METHODS: The minimal, maximal, and true colour-flow image diameters of the lumens of the grafts were measured and stenoses, occlusions, and dilatations were evaluated and compared with angiographic findings. RESULTS: The sensitivity for detection in > 50% stenoses and in total occlusions was 75% while specificity was 100%. Only one 40% stenosis had been overlooked in whole. The maximal difference of stenosis by two methods was otherwise 20%. CONCLUSIONS: CDFI was in general able to expose stenoses in supra-aortic grafts, but the lack of visibility of some grafts throughout their length cause the false results. It appears that some angiographies can be replaced by CDFI and that this is a suitable method for follow-up in symptom-free patients with grafts.

Arterial wall thickness measurements by B mode ultrasonography in patients with Takayasu's arteritis.

OBJECTIVE: To assess the feasibility and potential diagnostic usefulness of arterial ultrasonography in Takayasu's arteritis. METHODS: The total wall, intimal + medial, and adventitial thickness of the common carotid, subclavian and common femoral arteries, and of the abdominal aorta, were examined by B mode ultrasonography in 16 patients with Takayasu's arteritis and 16 healthy control subjects. RESULTS: The mean total wall and intimal + medial thickness of all arteries other than the common femoral were significantly increased in Takayasu's arteritis. Long segments of homogeneous circumferential wall thickening in multiple vessels were characteristic. When the common carotid and subclavian arteries and the abdominal aorta were examined, each individual with Takayasu's arteritis had at least one artery with total wall thickness exceeding the reference range in controls. CONCLUSIONS: B mode ultrasonography is able to expose the widespread arterial wall thickening characteristic of Takayasu's arteritis and may provide a useful tool for the detection and follow up of this disease.

Right and left atrial phasic volumetric function in mildly symptomatic dilated and hypertrophic cardiomyopathy: cine MR imaging assessment.

PURPOSE: To characterize biatrial phasic volumetric function in dilated and hypertrophic cardiomyopathy with cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eight patients with dilated cardiomyopathy (mean age, 47 years), eight with hypertrophic cardiomyopathy (mean age, 39 years), and eight healthy subjects (mean age, 41 years) underwent cardiac-gated long-axis cine MR imaging of both atria. RESULTS: Left atrial minimum volume averaged 94 mL +/- 37 (standard deviation) in dilated cardiomyopathy, 86 mL +/- 40 in hypertrophic cardiomyopathy, and 51 mL +/- 14 in control subjects (P = .04). Left atrial ejection fraction averaged 16% +/- 6 in dilated cardiomyopathy, 19% +/- 12 in hypertrophic cardiomyopathy, and 28% +/- 7 in control subjects (P = .03). Right atrial minimum volume and ejection fraction were not altered in either form of cardiomyopathy. The normalized filling and emptying rates of either atrium were decreased in both forms of cardiomyopathy. CONCLUSION: In mildly symptomatic dilated and hypertrophic cardiomyopathy, and left atrium is enlarged and its relative cyclic volume changes are reduced. The right atrium is of normal size, but its reservoir function is compromised particularly in dilated cardiomyopathy. Three-dimensional volume measurements with cine MR imaging enable the exposure of altered atrial volumetric function.

A simplified method for the determination of left atrial size and function using cine magnetic resonance imaging.

This work aimed at developing a rapid and clinically applicable method for the assessment of left atrial size and function using magnetic resonance imaging (MRI). We studied 17 healthy subjects and 26 cardiac patients. Left atrial cine MRI with 50 ms phases was made in 6-12 contiguous long-axis sections encompassing the entire atrial cavity. A volume-time curve was reconstructed to measure the minimum and maximum volumes as well as the fractional volume change, reservoir function, ejection fraction, and mean filling and emptying rates of the left atrium. The image section with the largest left atrial area was then selected and a comparable area-time curve was reconstructed. The atrial phasic areas and functional indices were determined analogously to the volume-based assessment. The contours of atrial area-time and volume-time curves agreed closely in individual subjects. All area-based left atrial measurements distinguished cardiac patients as a group from healthy persons. The combined specificity of the area-based analyses was 92% and the sensitivity, 65%, in identifying abnormal results in individual patients. The accuracy of the area-based data was best for the atrial minimum size, fractional change, reservoir function, and mean filling rate. The estimated time savings with the simplified method were 5 to 6 h per patient. Left atrial size and function can be studied by reconstructing a phasic atrial area-time curve with cine MRI. Atrial enlargement and abnormalities of filling and reservoir function can be reliably identified, but if data on conduit or stroke function are crucial the three-dimensional MRI technique is still recommended.

Right atrial MR imaging studies of cadaveric atrial casts and comparison with right and left atrial volumes and function in healthy subjects.

PURPOSE: To assess magnetic resonance (MR) imaging of the right atrium by measuring volumes of right atrial casts and determining right atrial volume cycles in healthy subjects. MATERIALS AND METHODS: Fourteen human cadaveric atrial casts were imaged and right atrial volumes of eight subjects were measured with cardiac-gated cine MR. Volumes were calculated and right and left atrial volumes were compared. RESULTS: Measured volumes of right atrial casts correlated well (r = .99, P < .001) with true volumes with a small underestimation noted (-7.2 mL +/- 2.3 [standard deviation], P < .001). The maximum in vivo right atrial volume averaged 77 mL/m2 +/- 11 of body area. The right atrial reservoir and conduit functions accounted for, on average, 58% and 19%, respectively, of the ventricular stroke volume; the remaining 23% came from atrial contraction. Right-to-left peak volume ratio averaged 1.41 +/- 0.15 (P < .001), and all volume measurements except conduit volumes were statistically significantly larger in the right atrium than the left. CONCLUSIONS: MR imaging provides a reliable means to study right atrial volumes and phasic function.

Acute rhabdomyolysis: evaluation with magnetic resonance imaging compared with computed tomography and ultrasonography.

Fifteen patients with acute rhabdomyolysis were evaluated with low field magnetic resonance (MR) imaging and the results compared with those obtained using computed tomography (CT) and ultrasonography (US). With MR imaging, abnormal muscles with areas of increased signal intensity were seen in every patient, which probably reflects increased water content or increased mobility of water molecules caused by inflammatory reaction and oedema in the injured and necrotic muscles. Computed tomography without intravenous contrast medium demonstrated abnormal muscles in most patients examined with this modality. The CT findings consisted of areas of focal hypodensity in muscles. With US, abnormal muscles were seen in less than half of the patients studied. The normal structure of striated muscle was focally disturbed and areas of both decreased and increased echogenicity were found. Magnetic resonance imaging had a higher sensitivity in the detection of abnormal muscles than CT or US (100%, 62% and 42%, respectively). The findings of all these modalities are non-specific, but together with the clinical and laboratory data they confirm the diagnosis of rhabdomyolysis. The information gained from imaging studies is useful in the assessment of the extent and distribution of rhabdomyolysis. The precise identification of affected muscle compartments by MR imaging is valuable when surgical fasciotomy is considered for treatment; the procedure can then be appropriately directed to the compartments with clearly abnormal muscles.

Bilateral renal artery dissections: unusual complication of polyarteritis nodosa.

A case of polyarteritis nodosa with the acute complications of multiple bilateral real artery dissection, perirenal haemorrhage and kidney infarction is described. The diagnosis of polyarteritis nodosa was established on the basis of angiographical and clinical findings. Follow-up arteriograms and CT-findings after prednisone therapy are discussed.