Quantitative determination of regional extravascular lung water and regional blood volume in congestive heart failure

Regional extravascular lung water (rELW) and blood volume (rBV) in five controls and 14 patients with congestive heart failure (CHF) were measured by constant infusion of H215O and inhalation of 11CO using positron emission tomography (PET). The analysis of 18 regions per patient revealed a relatively homogeneous level of rELW in the controls (mean = 0.11 +/- 0.02 g/cc; range, 0.08-0.21), whereas this increase in patients with CHF (0.17 +/- 0.02 g/cc; range, 0.10-0.51). The rBV was 0.21 +/- 0.02 g/cc in the controls and 0.17 +/- 0.02 g/cc in patients with CHF. A good correlation was found between the severity of chronic heart failure (according to the grading of the New York Heart Association) and mean extravascular lung water (ELW) (r = 0.69), as well as between CHF and the ratio rELW/rBV (r = 0.87); however, the correlation to hemodynamic data was less satisfactory (cardiac index, r = 0.45; pulmonary capillary wedge pressure, r = 0.47; ejection fraction, r = 0.60). In supine controls, a progressive decrease in regional blood volume from the basal to the apical regions was observed, whereas the differences in ELW were only small. In patients with chronic heart failure, ELW in the basal parts was markedly increased, whereas in the apical regions, only minor deviations from the controls were observed. In the basal regions of these patients, the blood volume was reduced by about 30%. Instead of the normal basoapical gradient of blood volume, these patients showed a rather flat distribution. Radiographic findings of pulmonary edema generally appeared together with an ELW level of greater than 0.14 g/cc.(ABSTRACT TRUNCATED AT 250 WORDS)     

The bedside determination of extravascular lung water

Using the formulae of Fazio and coworkers, we calculated the extravascular lung water per unit of blood volume (ELW/V) and per unit of blood flow (ELW/F) after intravenous injection of ^113mIntransferrin as the blood label, and ¹²³I-antipyrine as the diffusible, i.e. water label. Time-activity curves were recorded over the right anterior upper chest wall using a mobile detector. The curves were digitalized and fitted to a gamma-variate using a GAMMA-11 computer. Area over height calculations gave the mean transit times . Sixteen control subjects, without evidence of cardiac or pulmonary disease, and 10 patients, with clinical and radiological evidence of left heart failure, were examined. In the control group ELW/V was 0.37±0.17 and ELW/F 3.39±1.56 (mean±1 SD). In the patients ELW/V was 0.71±0.26 and ELW/F 13.10±5.67. The difference between both ELW/V and ELW/F for the control group and the patient group is statistically significant. Our values for ELW/V both in patients and control subjects are very similar to those obtained by Fazio and coworkers using H₂ ¹⁵O. However, our values for ELW/F differed from those of Fazio; this could be partly due to dependence of this parameter on the cardiac output.     

Relationships between brain water content and diffusion tensor imaging parameters (apparent diffusion coefficient and fractional anisotropy) in multiple sclerosis

Fifteen multiple sclerosis patients were examined by diffusion tensor imaging (DTI) to determine fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in a superventricular volume of interest of 8×8×2 cm³ containing gray matter (GM) and white matter (WM) tissue. Point resolved spectroscopy 2D-chemical shift imaging of the same volume was performed without water suppression. The water contents and DTI parameters in 64 voxels of 2 cm³ were compared. The water content was increased in patients compared with controls (GM: 244±21 vs. 194±10 a.u.; WM: 245±32 vs. 190±11 a.u.), FA decreased (GM: 0.226±0.038 vs. 0.270±0.020; WM: 0.337±0.044 vs. 0.402±0.011) and ADC increased [GM: 1134±203 vs. 899±28 (×10⁻⁶ mm²/s); WM: 901±138 vs. 751±17 (×10⁻⁶ mm²/s)]. Correlations of water content with FA and ADC in WM were strong (r=−0.68, P<0.02; r=0.75; P<0.01, respectively); those in GM were weaker (r=−0.50, P<0.05; r=0.45, P<0.1, respectively). Likewise, FA and ADC were more strongly correlated in WM (r=−0.88; P<0.00001) than in GM (r=−0.69, P<0.01). The demonstrated relationship between DTI parameters and water content in multiple sclerosis patients suggests a potential for therapy monitoring in normal-appearing brain tissue.     

Factors influencing the variations of ejection fraction during exercise in chronic aortic regurgitation

The influence of left ventricular volume variations and regurgitant fraction variations upon left ventricular ejection fraction, during exercise was examined using equilibrium radionuclide angiography in patients suffering from aortic regurgitation. Ejection fraction (EF), regurgitant fraction (RF), end diastolic volume (EDV) and end systolic volume (ESV) variations from rest to peak exercise were determined in 44 patients suffering from chronic aortic regurgitation (AR) and in 8 healthy volunteers (C). In C, EF increased (+0.10±0.03, P<0.01) and ESV decreased significantly (-23%±12%, P<0.01) RF and EDV did not vary significantly. In AR patients, EF, EDV and ESV did not vary significantly because of important scattering of individual values. Changes in EF and ESV were inversely correlated (r=-0.79, P<0.01) and RF decreased significantly (-0.12±0.10, P<0.01). Volumes and EF changes during exercise occurred in three different ways. In a 1st subgroup of 7 patients, EF increased (+0.09±0.03, P<0.05) in conjunction with a reduction of ESV (-24%±12%, P<0.05) without a significant change in EDV. In a 2nd group of 22 patients. EF decreased (-0.04±0.07, P<0.01) in association with an increase in ESV (+17%±16%, P<0.01) and no change in EDV. In a 3rd subgroup of 15 patients, EF decreased (-0.02±0.06, P<0.01) despite a reduction in ESV (-7%±6%, P<0.01) because of a dramatic EDV decrease (-10%±6%, P<0.05). In this subgroup, changes in EF were inversely correlated with changes in ESV (r=-0.55, P<0.01) and positively related to EDV variations (r=0.42, P=0.02). EDV related to EDV variations (r=0.42, P=0.02). EDV changes were weakly, but significantly, correlated to RF decrease (r=0.39, P<0.05). We conclude that changes in left ventricular ejection fraction during exercise in patients with chronic aortic regurgitation are significantly related in some patients to changes in ventricular loading conditions as well as contractile state. Therefore, a correct interpretation of EF changes during exercise requires the simultaneous determination of changes in LV volumes.Abbreviations EDV end diastolic volume - EF ejection fraction - ESV end systolic volume - LV left ventricle - RV right ventricle     

Assessment of right ventricular oxidative metabolism by PET in patients with idiopathic dilated cardiomyopathy undergoing cardiac resynchronisation therapy

Purpose Right ventricular (RV) performance is known to have prognostic value in patients with congestive heart failure (CHF). Cardiac resynchronisation therapy (CRT) has been found to enhance left ventricular (LV) energetics and metabolic reserve in patients with heart failure. The interplay between the LV and RV may play an important role in CRT response. The purpose of the study was to investigate RV oxidative metabolism, metabolic reserve and the effects of CRT in patients with CHF and left bundle brach block. In addition, the role of the RV in the response to CRT was evaluated.Methods Ten patients with idiopathic dilated cardiomyopathy who had undergone implantation of a biventricular pacemaker 8±5 months earlier were studied under two conditions: CRT ON and after CRT had been switched OFF for 24 h. Oxidative metabolism was measured using [¹¹C]acetate positron emission tomography (K_mono). The measurements were performed at rest and during dobutamine-induced stress (5 g/kg per minute). LV performance and interventricular mechanical delay (interventricular asynchrony) were measured using echocardiography.Results CRT had no effect on RV K_mono at rest (ON: 0.052±0.014, OFF: 0.047±0.018, NS). Dobutamine-induced stress increased RV K_mono significantly under both conditions but oxidative metabolism was more enhanced when CRT was ON (0.076±0.026 vs 0.065±0.027, p=0.003). CRT shortened interventricular delay significantly (45±33 vs 19±35 ms, p=0.05). In five patients the response to CRT was striking (32% increase in mean LV stroke volume, range 18–36%), while in the other five patients no response was observed (mean change +2%, range –6% to +4%). RV K_mono and LV stroke volume response to CRT correlated inversely (r=–0.66, p=0.034). None of the other measured parameters, including all LV parameters and electromechanical parameters, were associated with the response to CRT. In responders, RV K_mono with CRT OFF was significantly lower than in non-responders (0.036±0.01 vs 0.058±0.02, p=0.047).Conclusion CRT appears to enhance RV oxidative metabolism and metabolic reserve during stress. Patients responding to CRT appear to have lower RV oxidative metabolism at rest, suggesting that the RV plays a significant role in the response to CRT.     

Quantification of regional extravascular lung water in dogs with positron emission tomography,using constant infusion of 15O-labeled water

Continuous infusion of ¹⁵O-labeled water allows a quantitative measurement of the total water pool in the chest region by positron emission tomography (PET). By subsequent inhalation of ¹¹CO the intravascular space (blood pool) can be quantitated as well. After a suitable normalization of the intravascular activities the extravascular water can be determined by subtraction of the blood pool from the water pool. The regional extravascular lung water distribution can be visualized in tomographic slices. The method was validated in an animal experiment using five dogs. They were measured before and after induction of a lung edema by IV injection of oleic acid. The increase of extravascular lung water was monitored by the thermodye-dilution method (TDD). The correlation of extravascular lung water as measured by TDD with PET measurements is good (r=0.94). The PET values agree also with gravimetric lung water determinations. An absolute quantitation of regional extravascular lung water is possible after absorption correction of the PET data via transmission measurements and calibration of the camera system. The uncertainty in the absolute quantification is±20%. In the experiments described here the mean extravascular lung water was 0.13 g/cm³ before and 0.25 g/cm³ after induction of lung edema.     

Effects of perindopril on cardiac sympathetic nerve activity in patients with congestive heart failure: comparison with enalapril

Purpose The production of aldosterone in the heart is suppressed by the angiotensin-converting enzyme (ACE) inhibitor perindopril in patients with congestive heart failure (CHF). Moreover, perindopril has been reported to have more cardioprotective effects than enalapril.Materials and methods Forty patients with CHF [left ventricular ejection fraction (LVEF) <45%; mean 33±7%] were randomly assigned to perindopril (2 mg/day; n=20) or enalapril (5 mg/day; n=20). All patients were also treated with diuretics. The delayed heart/mediastinum count (H/M) ratio, delayed total defect score (TDS) and washout rate (WR) were determined from ¹²³I-meta-iodobenzylguanidine (MIBG) images, and plasma brain natriuretic peptide (BNP) concentrations were measured before and 6 months after treatment. The left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV) and LVEF were also determined by echocardiography.Results After treatment, in patients receiving perindopril, TDS decreased from 39±10 to 34±9 (P<0.01), H/M ratios increased from 1.62±0.27 to 1.76±0.29 (P<0.01), WR decreased from 50±14% to 42±14% (P<0.05) and plasma BNP concentrations decreased from 226±155 to 141±90 pg/ml (P<0.0005). In addition, the LVEDV decreased from 180±30 to 161±30 ml (P<0.05) and the LVESV decreased from 122±35 to 105±36 ml (P<0.05). Although the LVEF tended to increase, the change was not statistically significant (from 33±8% to 36±12%; P=NS). On the other hand, there were no significant changes in these parameters in patients receiving enalapril.Conclusion Plasma BNP concentrations, ¹²³I-MIBG scintigraphic and echocardiographic parameters improved after 6 months of perindopril treatment. These findings indicate that perindopril treatment can ameliorate the cardiac sympathetic nerve activity and the left ventricular performance in patients with CHF.     

Involvement of pulmonary endothelial cell injury in the pathogenesis of pulmonary fibrosis: clinical assessment by 123I-MIBG lung scintigraphy

Purpose Pulmonary microvascular endothelial injury may be involved in the pathogenesis of pulmonary fibrosis (PF). The aim of this study was to evaluate the pulmonary vascular status in patients with PF by lung scintigraphic assessment of ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG), which reflects latent endothelial cell lesions.Methods We assessed lung ¹²³I-MIBG kinetics and clinical indices in 23 PF patients and 16 controls. Mean uptake ratios of lung to mediastinum (L/M) were calculated in anterior planar images at 30 (early image) and 270 (delayed image) min after intravenous injection of ¹²³I-MIBG. The pulmonary mean washout rate (WR) of ¹²³I-MIBG was also calculated.Results The L/M ratio in early images, but not in delayed images, was significantly lower in the PF patients than in the controls (L/M_early 1.41±0.14 vs 1.53±0.10, p<0.01; L/M_delayed 1.28±0.10 vs 1.33±0.07, p=NS). WR was significantly reduced in the PF patients compared with the controls (28.6%±3.1% vs 34.2%±5.1%, p<0.001). In the study subjects (PF patients plus controls) there were significant relationships between lung WR of ¹²³I-MIBG and other diagnostic parameters for the severity of PF, such as vital capacity (r=0.625, p<0.0001), total lung capacity (r=0.691, p<0.0001), carbon monoxide diffusing capacity (r=0.622, p<0.0001), serum angiotensin-converting enzyme activity (r=0.422, p<0.01), carbohydrate antigen KL-6 levels (r=–0.495, p<0.01) and surfactant protein-D levels (r=–0.461, p<0.01). When control subjects were excluded, similar significant correlations were observed between WR and %TLC (r=0.508, p<0.05), DL_CO (r=0.593, p<0.01) and serum ACE activity (r=0.515, p<0.05) in the PF patients.Conclusion These results suggest that endothelial cell injury plays a significant role in the pathogenesis of PF, and that lung WR of ¹²³I-MIBG, which is a specific marker of endothelial damage, can serve as a novel diagnostic tool to evaluate the functional severity of PF.     

31P-MR spectroscopic imaging in hypertensive heart disease

Hypertensive heart disease (HHD) causes structural changes (e.g., fibrosis) that result in diastolic and systolic myocardial dysfunction. Alterations of ³¹P metabolism and cardiac energy impairments were assessed in patients with HHD by MR spectroscopy (MRS) and correlated with left ventricular systolic function. Thirty-six patients with HHD and 20 healthy controls (mean age 35.2±10.7 years) were examined with ³¹P-MRS at 1.5 T by using an ECG-gated CSI sequence. Twenty-five patients (mean age 64.3±9.3 years) had diastolic dysfunction, but preserved systolic function (HHD-D), whereas 11 patients (62.3±11.4 years) suffered from additional impaired systolic function (HHD-S). In both patient groups, the PCr/γ-ATP ratio was lower than in the controls (controls: 2.07±0.17; P<0.001), and in HHD-S was lower than in HHD-D (1.43±0.21 vs. 1.65±0.25; P=0.012). PCr/γ-ATP ratios were linearly correlated with LVEF (Pearson's r: 0.39; P=0.025). In the HHD-S group, the PDE/γ-ATP ratio was significantly lower (0.56±0.36) than in the controls (1.14±0.42; P=0.001). In contrast to the group of HHD-D patients, whose slightly decreased PCr/γ-ATP ratios compared to controls may be explained by age differences, the more distinct changes observed in HHD-S patients indicate an altered energy metabolism. The observed metabolic changes were related to functional impairments, as indicated by a reduced LVEF. Reduced PDE/ATP ratios indicate changes in the phospholipid metabolism.     

Asynchronous filling in ischemic heart disease and hypertrophic cardiomyopathy

A multigated blood-pool study was performed to assess regional and global emptying and filling in 16 patients with hypertrophic cardiomyopathy (HCM), 43 patients with ischemic heart disease (IHD), and 14 controls. The regional volume curve was fitted using second-order harmonics in the Fourier series, while the global left-ventricular volume curve was fitted using third-order harmonics. As asynchronous indices, the standard deviations (SD) in distribution histograms of time to end-systole (TES), time to peak ejection (TPE), and time to peak filling (TPF) were obtained in the left ventricle. In patients with IHD, the TPF-SD was higher (14.4±11.3°) than the TES-SD (7.8±5.1°) and TPE-SD (8.1±5.9°), suggesting the presence of asynchronous filling. In patients with HCM, the TPF-SD was also higher (11.6±11.1°) than the TES-SD (3.5±2.4°) and TPE-SD (6.2±4.4°). The phase delay was localized in the anteroseptal or apical region in all 5 HCM patients with abnormal wall motion, while it corresponded with the region of abnormal wall motion in the patients with IHD. The TPF-SD was inversely correlated with the left-ventricular ejection fraction (r=-0.46), peak filling rate (r=-0.50), and the ratio of peak filling rate to peak ejection rate (r=-0.52), suggesting that asynchronous filling is related to global diastolic disturbance. We conclude that asynchronous filling is often present in patients with IHD and HCM, and that our technique can be used to obtain a quantitative assessment of regional asynchronous emptying and filling in these diseases.     

Analysis of the human brain in primary progressive multiple sclerosis with mapping of the spatial distributions using 1H MR spectroscopy and diffusion tensor imaging

Primary progressive multiple sclerosis (ppMS; n=4) patients and controls (n=4) were examined by 1H magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in order to map choline (Cho), creatine and N-acetylaspartate (NAA), the fractional anisotropy (FA) and the apparent diffusion constant (ADC). After chemical shift imaging (point-resolved spectroscopy, repetition time/echo time 1,500 ms/135 ms) of a supraventricular volume of interest of 8×8×2 cm³ (64 voxels) MRS peak areas were matched to the results of DTI for the corresponding volume elements. Mean FA and NAA values were reduced in the ppMS patients (P<0.01, both) and the ADC increased (P<0.02). The spatial distribution of NAA showed strong correlation to ADC in both ppMS patients and controls (r =–0.74 and r= –0.70; P<0.00001, both), and weaker correlations to FA (r=0.49 and r=0.41; P<0.00001, all). FA and ADC also correlated significantly with Cho in patients and controls (P<0.00001, all). The relationship of Cho and NAA to the ADC and the FA and thus to the content of neuronal structures suggests that these metabolite signals essentially originate from axons (NAA) and the myelin sheath (Cho). This is of interest in view of previous reports in which Cho increases were associated with demyelination and the subsequent breakdown of neurons.     

Assessment of right ventricular function by 16-detector-row CT: comparison with magnetic resonance imaging

The purpose of this study was to determine right ventricular (RV) function from 16-detector-row CT by using two different software tools in comparison with MRI. Nineteen patients underwent cardiac CT. (1) With semiautomated contour detection software end-diastolic and end-systolic RV volumes were determined from short-axis CT reformations (MPR) created at every 10% of the RR-interval. (2) End-systolic and end-diastolic axial images were transformed to 3D to determine the volumes by using a threshold-supported reconstruction algorithm. Steady-state free-precession cine-MRI of the heart was done in short-axis orientation. RV function could not be analyzed in one patient because of sternal wire artifacts in MRI. Mean end-diastolic (155.4±54.6 ml) and end-systolic (79.1±37.0 ml) RV volumes determined with MPR correlated well with MRI [151.9±53.7 ml (r=0.98) and 75.0±36.0 ml (r=0.96), respectively (P<0.001)]. RV stroke volume (76.2±20.2 ml for MPR-CT, 76.9±20.7 ml for MRI, r=0.93) showed a good correlation and RV ejection fraction (50.8±8.4% for MPR-CT, 51.9±7.4% for MRI, r=0.74) only a moderate one. Threshold supported 3D reconstructions revealed insufficient correlations with MRI (r=0.31–0.59). MPR-based semiautomated analysis of cardiac 16 detector-row CT allows for RV functional analysis. The results correlate well with MRI findings. Threshold value-supported 3D reconstructions did not show satisfying results because of inhomogeneities of RV contrast enhancement.This paper contains parts of the doctoral thesis of Cand. Med. P. Bender.     

Quantification of pulmonary uptake of indium-111 labelled granulocytes in inflammatory bowel disease

This study describes a method for quantifying the pulmonary trapping of indium-111 labelled polymorphonuclear (PMN) cells in patients with inflammatory bowel disease (1131) in comparison to non-inflamed controls. Twenty patients with extensive IBD were studied by ¹¹¹In-PMN scintigraphy. Gamma-camera images were obtained at 2.5–4 h (early) and 20–25 h (late) after the injection of autologous PMNs labelled in plasma with ¹¹¹In-tropolonate. Local uptake in the chest, iliac bone marrow, spleen and liver was quantified as the counts per pixel per second per MBq of injected ¹¹¹In for both early and late scans. Fourteen subjects without inflammatory disease were studied as controls. IBD patients showed significantly greater loss of splenic activity between early and late scans compared with controls (mean ± SD: –35.7% ± 16.6% versus –4.5% ± 6.1%, P < 0.001). There was no significant difference between control and IBD groups with respect to liver and bone marrow uptake on both early and late scans. Chest uptake was significantly higher in patients with 11313 on both early (6.4 ± 1.6 cps/MBq/pix) and late (5.6 ± 1.5cps/MBq/pix) scans, compared with the controls (4.8 ± 1.3 cps/MBq/pix, P < 0.005 and 3.4 ± 1.0 cps/MBq/pix, P < 0.001 respectively). The chest uptake in the control group on the late scans demonstrated a significant linear correlation with iliac uptake (y=0.23x + 0.41, r=0.87, n=14). Assuming in controls that there is no parenchymal uptake of ¹¹¹In, this regression enables an estimate to be made, based on iliac counts, of the count rate from bone marrow in the chest wall. After subtraction of this from the total chest count rate, the true parenchymal uptake was derived, which averaged (2.86 ± 0.91) cps/MBq/pix in the IBD group compared to zero assumed in the control group. The higher lung ¹¹¹In-PMN uptake on the early scans in IBD compared to controls is suggested to reflect a combination of increased margination, compared to controls, and early migration, whilst the excess ¹¹¹In-PMN retention on late scans represents extravascular migration only. The bone marrow correction technique for quantification of pulmonary migration of ¹¹¹In-PMNs should prove useful for the evaluation of PMN kinetics in disease. Correspondence to: A.M. Peters     

Value of a radionuclide limb blood flow technique in the assessment of percutaneous balloon and dynamic angioplasty

In a prospective study, a radionuclide technique was used to evaluate the limb blood flow (LBF) changes in 30 patients undergoing dynamic (n=15) or balloon (n=15) angioplasty for arterial occlusions or stenoses, respectively. The results were compared with Doppler Ankle Brachial Index (DABI) and treadmill exercise tests. Whilst LBF values (ml of blood flow per 100 ml of limb volume per min) were significantly lower in limbs with arterial occlusion than stenosis (4.5±0.46 and 6.4±0.74, respectively; P<0.05), DABI provided no discrimination. Immediately after balloon angioplasty, there was a fall in DABI, from 0.60±0.05 to 0.47±0.04 (P<0.05), which rose 24 h later to 0.73±0.02 (P<0.01). Following dynamic angioplasty, DABI improved from 0.60±0.05 to 0.66±0.02 (P<0.05). At 3 weeks, the LBF improved from 4.6±0.66 to 11.1±0.53 (P<0.001) following dynamic angioplasty and from 6.2±0.68 to 8.53±0.81 (P<0.001) following balloon angioplasty. Normal LBF (> 10 ml/100 ml per min) was achieved in 80% of patients who underwent successful dynamic angioplasty but in only 36% of the balloon group (P<0.05, ²-test). Reproducibility of repeated LBF measurements in control limbs was superior to that of DABI. This was indicated by a lower coefficient of variation, 13.8% compared with 25.2%, and a higher correlation coefficient, r=0.79 compared with 0.27. Treadmill exercise tests were invalid or impossible in 30% of all occasions. There was a good correlation between the improvement in maximum walking distance on the treadmill and that in LBF (r=0.84, P<0.05). In conclusion, measurement of LBF using radionuclide technique is a potentially valuable method for the assessment of patients undergoing percutaneous angioplasty. LBF results are reproducible and correlate well with the improvement in walking ability, which cannot always be assessed objectively. Offprint requests to: A.A. Gehani     

A method for measuring mean circumferential fiber shortening rate from gated blood pool scans

Ejection fraction and ejection rate are easily obtained from gated cardiac images, but no method is available for calculating mean circumferential fiber shortening rate. We assumed that the cube root of left ventricular end-diastolic volume or counts is proportional to the minor axis of the left ventricle at end-diastole or end-systole. Mean circumferential fiber shortening rate is then equal to the [cube root of the end-diastolic volume (count) minus cube root of end-systolic volume (count)] divided by [cube root of end-diastolic volume (count) multiplied by the ejection time]. In 250 contrast ventriculograms, the standard mean circumferential fiber shortening rate (MCFSR) and that derived by the cube root method correlated well (r=0.94). The mean value of MCFSR (0.85±0.35) was greater than the cube root value (0.75±0.35) (P<0.001). The regression equation was y=0.86x+0.02. Similar correlations were obtained from gated radionuclide images using a semiautomated program (r=0.93) in 24 subjects or completely automated program (r=0.85) in 28 patients. The regression equation between MCFSR and that derived from the cube root of counts for the semiautomated program was y=0.82x+0.04 and for the automated program was y=0.84x+0.004. Similar correlations, slopes, and intercepts were seen using circumferential fractional shortening for angiographic data when correlated with both the semiautomated and automated gated blood pool scan programs. These data indicate that MCFSR and circumferential fractional shortening may be obtained from gated blood pool images using cube root estimates of end-diastolic and end-systolic radii with a high degree of correlation with the standard contrast ventriculographic technique.Supported by the Medical Research Service of the Veterans Administration Medical Center and NIH Research Grant HL 17682, awarded by the National Heart, Lung and Blood Institute     

Iron deposition in the precentral grey matter in patients with multiple sclerosis: A quantitative study using susceptibility-weighted imaging

Purpose

Several studies suggest that iron deposition may play a role in multiple sclerosis (MS) pathology. Three-dimensional (3D) enhanced T2*-weighted angiography (ESWAN) at 3T was used to quantify iron deposition in the precentral grey matter in MS and its relationship with disease duration, atrophy and Expanded Disability Status Scale (EDSS) scores.

Methods

We recruited 33 patients with diagnosis of clinically definite MS and 31 age- and sex-matched healthy controls who underwent conventional brain MRI, 3D-ESWAN and 3D T1sequences. We obtained the mean phase values (MPVs) of the precentral grey matter on ESWAN-filtered phase images and volume of the precentral gyrus on 3D T1 images. We investigated the correlation between precentral grey matter MPVs, precentral gyrus volume, disease duration and EDSS scores of MS patients and healthy controls.

Results

The precentral grey matter MPVs in MS patients and controls were 1870.83 ± 56.61 and 1899.22 ± 51.73 respectively and had significant difference in the MS group vs. the control group (t = −2.09, P = 0.04). There was significant negative correlation between precentral grey matter MPVs and disease duration (r = −0.365, P = 0.03). No correlation was found between MPVs and EDSS scores. Mean precentral gyrus volume in MS patients was 4368.55 ± 867.78 whereas in controls was 5701.00 ± 1184.03 with significant difference between volume of the precentral gyrus in MS patients compared to healthy controls (t = −5.167, P < 0.001). There was a positive correlation between MPVs and precentral gyrus volume (r = 0.291, P = 0.020).

Conclusions

Our study demonstrated that quantitative assessment of abnormal iron deposition in the precentral grey matter in MS patients can be measured using 3D-ESWAN.     

Distribution of Intramyocardially injected extracellular MR contrast medium: effects of concentration and volume

The purpose of this study was to assess the potential of intramyocardially injected Gd-DTPA solution as a marker for distribution of intramyocardially delivered therapeutic solutions. The effects of concentration and volume of the extracellular MR contrast medium Gd-DTPA on signal intensity and spatial extent of enhancement was determined after intramyocardial delivery. In anesthetized pigs (n=11), mixtures of Gd-DTPA (0.15, 0.1 and 0.05 mmol/ml) and Evans blue tissue dye (3%) were injected into the wall of the left ventricle. In each pig 1 ml of 0.15 mmol/ml, 2 ml of 0.1 ml and 3 ml of 0.05 mmol/ml Gd-DTPA were injected remote from each other. Arterial blood pressure, heart rate and ECG were monitored throughout the procedure. Five minutes after injections were performed, the pigs were killed and the hearts excised. T1-weighted spin-echo MR images were acquired to measure regional signal intensity (SI) and extent of the enhanced regions. The hearts were sliced and mass of blue stained regions was determined and compared with mass of enhanced areas on MRI. Gd-DTPA significantly (p<0.001) increased regional SI compared with remote myocardium in a concentration dependent fashion (109±4% at 0.05 mmol/ml, 202±7% at 0.1, and 327±6% at 0.15) while the mass of enhanced region was 0.6±0.1 g after injection of 1 ml, 1.4±0.2 g after 2 ml and 2.3±0.3 g after 3 ml (p<0.001). Regression and Bland-Altman analysis revealed that there was close correlation and agreement between MRI and histomorphometry (r=0.98, p<0.001). Magnitude and spatial extent of enhancement depend on concentration and volume of injected contrast medium. Intramyocardial injection of extracellular MR contrast media may be useful as a marker for the extent of distribution of intramyocardially delivered therapeutic solutions.     

Verification of Fourier phase and amplitude values from simulated heart motion using a hydrodynamic cardiac model

Using pusher-plate-type artificial hearts, changes in the degree of synchrony and stroke volume were compared to phase and amplitude calculations from the first Fourier component of individual-pixel time-activity curves generated from gated radionuclide images (RNA) of these hearts. In addition, the ability of Fourier analysis to quantify paradoxical volume shifts was tested using a ventricular aneurysm model by which the Fourier amplitude was correlated to known increments of paradoxical volume. Predetermined phase-angle differences (incremental increases in asynchrony) and the mean phase-angle difference calculated from RNAs showed an agreement of -7°±4.4° (mean ±SD). A strong correlation was noted between stroke volume and Fourier amplitude (r=0.98; P<0.0001) as well as between the paradoxical volume accepted by the aneurysm and the Fourier amplitude (r=0.97; P<0.0001). The degree of asynchrony and changes in stroke volume were accurately reflected by the Fourier phase and amplitude values, respectively. In the specific case of ventricular aneurysms, the data demonstrate that using this method, the paradoxically moving areas may be localized, and the expansile volume within these regions can be quantified.     

A comparison of maximal exercise and dipyridamole thallium-201 planar gated scintigraphy

Both symptom-limited maximal exercise and intravenously given dipyridamole stress (0.56 mg/kg over 4 min with a 2 min walk) gated thallium scans were performed in 22 patients undergoing coronary arteriography for the assessment of chest pain. All scans were acquired gated to the electrocardiogram in 3 projections and were reported for the presence and extent of defects in 5 myocardial segments in each view. In addition, left and right ventricular myocardial uptake and estimates of right and left lung and liver to left ventricular uptake were assessed relative to the injected dose of thallium-201. Overall, 190/310 segments were abnormal with exercise compared with 169/310 with dipyridamole. Segments were scored greater in extent in 90/310 cases with exercise, compared with 46/310 in which the defect was more extensive with dipyridamole (P <0.0005). Non-attenuation corrected percentage myocardial thallium uptakes were similar for both stresses: anterior percentage uptakes, 0.785%±0.230% with exercise versus 0.870%±0.217% with dipyridamole (NSD). Left and right lung and liver to left ventricle ratios were all significantly higher with dipyridamole than with exercise (1.587±0.408 versus 1.446±0.518, P <0.02; 1.78±0.479 versus 1.46±0.502, P <0.002; 2.598±0.788 versus 1.265 ± 0.386, P < 0.001, respectively). High right and left lung uptakes with dipyridarnole were strongly correlated with high exercise values (r =0.756, P <0.001; r =0.809, P < 0.001). The liver uptake was weakly correlated between the 2 different stress tests (r =0.483, P < 0.02). These results demonstrate that dipyridamole, at 0.56 mg/kg over 4 min, induces fewer and less extensive thallium perfusion defects than maximal exercise, and that liver and lung to myocardial ratios are higher with dipyridamole than with exercise.     

Forearm interosseous membrane imaging and anatomy

Objective To determine the regional thickness variation of the interosseous membrane (IOM) along the forearm and validate magnetic resonance imaging of the IOM with laser micrometry.Design and patients Axial thickness measurements of 12 cadaver forearms were obtained using magnetic resonance imaging (MRI) at radial, central, and ulnar locations. The specimens were dissected, and IOM thickness measured using a laser micrometer. MRI and laser measurements of the main and oblique IOM bundles were compared. An axial thickness profile was plotted versus forearm length, and radial, central, and ulnar positions were compared.Results The main bundle thickness was 2.18±0.20 mm using laser micrometry, which was not significantly different from MRI measurements (1.86±0.25 mm, p=0.11, power = 0.84). The dorsal oblique bundle thickness was not significantly different between measurement methods (2.93±0.77 mm and 3.30±1.64 mm using laser micrometry and MRI respectively, p=0.75, power = 0.04). Both methods demonstrated a progressive increase in thickness proximally within the forearm. MRI measurements demonstrated a significantly greater thickness increase in the radial location compared to the central location (slope = 2.26 and 1.05, r²=0.31 and 0.12 respectively, p<0.05). The ulnar slope was not significantly different from zero (r²=0.02, p>0.05).Conclusion Our findings describe the varying IOM anatomy using MRI, and determined the location of the clinically important IOM fiber bundles. This study confirms the accuracy of MR imaging of the IOM by comparison with a laser micrometer, and demonstrates the thickness variation along the forearm. This information may be used to identify changes in IOM anatomy with both acute IOM injury and chronic fiber attenuation.