Brain perfusion abnormalities in patients with euthyroid autoimmune thyroiditis

Purpose Brain perfusion abnormalities have recently been demonstrated by single-photon emission computed tomography (SPECT) in rare cases of severe Hashimotos thyroiditis (HT) encephalopathy; moreover, some degree of subtle central nervous system (CNS) involvement has been hypothesised in HT, but no direct evidence has been provided so far. The aim of this study was to assess cortical brain perfusion in patients with euthyroid HT without any clinical evidence of CNS involvement by means of ^99mTc-ECD brain SPECT. Sixteen adult patients with HT entered this study following informed consent.Methods The diagnosis was based on the coexistence of high titres of anti-thyroid auto-antibodies and diffuse hypoechogenicity of the thyroid on ultrasound in association with normal circulating thyroid hormone and TSH concentrations. Nine consecutive adult patients with non-toxic nodular goitre (NTNG) and ten healthy subjects matched for age and sex were included as control groups. All patients underwent ^99mTc-ECD brain SPECT. Image assessment was both qualitative and semiquantitative. Semiquantitative analysis was performed by generation of four regions of interest (ROI) for each cerebral hemisphere—frontal, temporal, parietal and occipital—and one for each cerebellar hemisphere in order to evaluate cortical perfusion asymmetry. The Asymmetry Index (AI) was calculated to provide a measurement of both magnitude and direction of perfusion asymmetry.Results As assessed by visual examination, ^99mTc-ECD cerebral distribution was irregular and patchy in HT patients, hypoperfusion being more frequently found in frontal lobes. AI revealed abnormalities in 12/16 HT patients, in three of the nine NTNG patients and in none of the normal controls. A significant difference in the mean AI was found between patients with HT and both patients with NTNG (p<0.003) and normal controls (p<0.001), when only frontal lobes were considered.Conclusion These results show the high prevalence of brain perfusion abnormalities in euthyroid HT. These abnormalities are similar to those observed in cases of severe Hashimotos encephalopathy and may suggest a higher than expected involvement of CNS in thyroid autoimmune disease.     

Perfusion abnormality of the caudate nucleus in patients with paroxysmal kinesigenic choreoathetosis

Purpose Previous cerebral blood flow and glucose metabolism studies suggest that the basal ganglia or thalamus is involved in the pathogenesis of paroxysmal kinesigenic choreoathetosis (PKC). However, the underlying cerebral abnormalities in idiopathic PKC have not been elucidated. To localise cerebral perfusion abnormalities in PKC, we performed interictal brain perfusion ^99mTc-ethylcysteinate dimer (ECD) single-photon emission computed tomography (SPECT) in PKC patients and in normal controls.Methods Sixteen patients with idiopathic PKC and 18 age- and sex-matched normal controls were included. The patients were de novo diagnosed as having PKC, or had not taken medication for at least 3 months; none of them had structural abnormalities on MRI. Patients had a history of PKC attacks of a duration not exceeding 5 min and starting either on one side or on both sides of the body. These attacks were always induced by a sudden initiation of voluntary movement. PKC attacks were recorded in a hospital after being induced by neurology staff in 13 of the 16 patients. Interictal brain perfusion ^99mTc-ECD SPECT was performed in all 16 patients and 18 normal controls. Differences between the cerebral perfusion in the PKC group and the normal control group were tested by statistical parametric mapping. Students t test was used for inter-group comparisons.Results Compared with normal controls, patients with idiopathic PKC showed interictal hypoperfusion in the posterior regions of the bilateral caudate nuclei (false discovery rate-corrected P<0.001 with a small volume correction).Conclusion This study showed that cerebral perfusion abnormality of bilateral caudate nuclei is present in idiopathic PKC.     

Increased accuracy of the carbon-14d-xylose breath test in detecting small-intestinal bacterial overgrowth by correction with the gastric emptying rate

To date, there is no general agreement as to which test is to be preferred for the diagnosis of small-intestinal bacterial overgrowth. The 1-g carbon-14d-xylose breath test has been proposed as a very sensitive and specific test for the diagnosis of bacterial overgrowth. However, in patients with severe gastrointestinal motor dysfunction, the lack of consistent delivery of¹⁴C-d-xylose to the region of bacterial contamination may result in a negative result. The aim of this study was to determine whether the accuracy of¹⁴C-d-xylose breath test for detecting bacterial overgrowth can be increased by correction with the gastric emptying rate of¹⁴C-d-xylose. Ten culture-positive patients and ten culture-negative controls were included in the study. Small-intestinal aspirates for bacteriological culture were obtained endoscopically. A liquid-phase gastric emptying study was performed simultaneously to assess the amount of¹⁴C-d-xylose that entered the small intestine. The results of the percentage of expired¹⁴CO₂ at 30 min were corrected with the amount of¹⁴C-d-xylose that entered the small intestine. There were six patients in the culture-positive group with a¹⁴CO₂ concentration above the normal limit. Three out of four patients with initially negative results using the uncorrected method proved to be positive after correction. All these three patients had prolonged gastric emptying of¹⁴C-d-xylose. When compared with cultures of small-intestine aspirates, the sensitivity and specificity of the uncorrected¹⁴C-d-xylose breath test were 60% and 90%, respectively. In contrast, the sensitivity and specificity of the corrected¹⁴C-d-xylose breath test improved to 90% and 100%, respectively. In conclusion, using the gastric emptying rate of¹⁴C-d-xylose as a correcting factor, we found a higher sensitivity and specificity for the¹⁴C-d-xylose breath test in the detection of small-intestinal bacterial overgrowth than were achieved with the conventional method.     

Assessment of myocardial perfusion and viability from routine contrast-enhanced 16-detector-row computed tomography of the heart: preliminary results

To assess the diagnostic accuracy of 16-detector-row computed tomography (16DCT) of the heart in the assessment of myocardial perfusion and viability in comparison to stress perfusion magnetic resonance imaging (SP-MRI) and delayed-enhancement magnetic resonance imaging (DE-MRI). A number of 30 patients underwent both 16DCT and MRI of the heart. Contrast-enhanced 16DCT data sets were reviewed for areas of myocardium with reduced attenuation. Both CT and MRI data were examined by independent reviewers for the presence of myocardial perfusion defects or myocardial infarctions (MI). Volumetric analysis of the hypoperfusion areas in CT and the infarct sizes in DE-MRI were performed. According to MRI, myocardial infarctions were detected in 11 of 30 cases, and perfusion defects not corresponding to an MI were detected in six of 30 patients. CTA was able to detect ten of 11 MI correctly (sensitivity 91%, specificity 79%, accuracy 83%), and detected three of six hypoperfusions correctly (sensitivity 50%, specificity 92%, accuracy 79%). Assessing the volume of perfusion defects correlating to history of MI on the CT images, a systematic underestimation of the true infarct size as compared to the results of DE-MRI was found (P<0.01). Routine, contrast-enhanced 16-detector row CT of the heart can detect chronic myocardial infarctions in the majority of cases, but ischemic perfusion defects are not reliably detected under resting conditions.Dr. Sanzs work is supported in part by a Research Grant (Beca para la Formación en Investigación Post-Residencia) from the Spanish Society of Cardiology.     

Quantitative simultaneous 99mTc-ECD/123I-FP-CIT SPECT in Parkinson’s disease and multiple system atrophy

Purpose The purpose of this study was to investigate the feasibility and utility of dual-isotope SPECT for differential diagnosis of idiopathic Parkinsons disease (IPD) and multiple system atrophy (MSA).Methods Simultaneous ^99mTc-ECD/¹²³I-FP-CIT studies were performed in nine normal controls, five IPD patients, and five MSA patients. Projections were corrected for scatter, cross-talk, and high-energy penetration, and iteratively reconstructed while correcting for patient-specific attenuation and variable collimator response. Perfusion and dopamine transporter (DAT) function were assessed using voxel-based statistical parametric mapping (SPM2) and volume of interest quantitation. DAT binding potential (BP) and asymmetry index (AI) were estimated in the putamen and caudate nucleus.Results Striatal BP was lower in IPD (55%) and MSA (23%) compared to normal controls (p<0.01) , and in IPD compared to MSA (p<0.05). AI was greater for IPD than for MSA and controls in both the caudate nucleus and the putamen (p<0.05). There was significantly decreased perfusion in the left and right nucleus lentiformis in MSA compared to IPD and controls (p<0.05).Conclusion Dual-isotope studies are both feasible in and promising for the diagnosis of parkinsonian syndromes.     

Imaging characteristic of dual-phase <Superscript>18</Superscript>F-florbetapir (AV-45/Amyvid) PET for the concomitant detection of perfusion deficits and beta-amyloid deposition in Alzheimer’s disease and mild cognitive impairment

Purpose

We investigated dual-phase ¹⁸F-florbetapir (AV-45/Amyvid) PET imaging for the concomitant detection of brain perfusion deficits and beta-amyloid deposition in patients with Alzheimer’s disease (AD) and amnestic mild cognitive impairment (MCI), and in cognitively healthy controls (HCs).

Methods

A total of 82 subjects (24 AD patients, 44 MCI patients and 14 HCs) underwent both dual-phase ¹⁸F-AV-45 PET and MRI imaging. Dual-phase dynamic PET imaging consisted of (1) five 1-min scans obtained 1?–?6 min after tracer injection (perfusion ¹⁸F-AV-45 imaging, pAV-45), and (2) ten 1-min scans obtained 50?–?60 min after tracer injection (amyloid ¹⁸F-AV-45 imaging). Amyloid-negative MCI/AD patients were excluded. Volume of interest analysis and statistical parametric mapping of pAV-45 and ¹⁸F-AV-45 images were performed to investigate the perfusion deficits and the beta-amyloid burden in the three study groups. The associations between Mini-Mental State Examination (MMSE) scores and global perfusion deficits and amyloid deposition were investigated with linear and segmental linear correlation analyses.

Results

HCs generally had normal pAV-45 findings, whereas perfusion deficits were evident in the hippocampus, and temporal, parietal and middle frontal cortices in both MCI and AD patients. The motor-sensory cortex was relatively preserved. MMSE scores in the entire study cohort were significantly associated with the degree of perfusion impairment as assessed by pAV-45 imaging (r?=?0.5156, P?<?0.0001). ¹⁸F-AV-45 uptake was significantly higher in AD patients than in the two other study groups. However, the correlation between MMSE scores and ¹⁸F-AV-45 uptake in MCI patients was more of a binary phenomenon and began in MCI patients with MMSE score 23.14 when ¹⁸F-AV-45 uptake was higher and MMSE score lower than in patients with early MCI. Amyloid deposition started in the precuneus and the frontal and temporal regions in early MCI, ultimately reaching the maximum burden in advanced MCI.

Conclusion

Our results indicate that brain perfusion deficits and beta-amyloid deposition in AD follow different trajectories that can be successfully traced using dual-phase ¹⁸F-AV-45 PET imaging.

     

In vivo determination of the kinetic parameters of glucose transport in the human brain using 11C-methyl-d-glucose (CMG) and dynamic positron emission tomography (dPET)

A method was developed to measure simultaneously (1) the rate constants for glucose influex and glucose efflux, and (2) the Michaelis-Menten constant (K _M ) and maximal velocity (V _max) for glucose transport across the blood-brain barrier (BBB) in any selected brain area. Moreover, on the basis of a mathematical model, the local perfusion rate (LPR) and local unidirectional glucose transport rate (LUGTR) are calculated in terms of parameters of the time-activity curves registered over different brain regions; ¹¹C-methyl-d-glucose (CMG) is used as an indicator. The transaxial distribution of activity in the organism is registered using dynamic positron-emission tomography (dPET). The method was used in 4 normal subjects and 50 patients with ischemic brain disease. In normals, the rate constant for CMG efflux was found to be 0.25±0.04 min^-1 in the cortex and 0.12±0.02 min^-1 in white matter. In the cortex, the K _M was found to be 6.42 mol/g and the V _max was 2.46 mol/g per minute. The LUGTR ranged from 0.43 to 0.6 mol/g per minute in the cortex, and from 0.09 to 0.12 mol/g per minute in white matter. The LPR was calculated to be 0.80–0.98 ml/g per minute for the cortex and 0.2–0.4 ml/g per minute for white matter. In patients with stroke, the ischemic defects appeared to be larger in CMG scans than in computed x-ray tomography (CT) scans. Prolonged reversible ischemic neurological deficit was associated with a significant fall in the LUGTR but no change in the LPR in the corresponding cerebral cortex. Normal LUGTR and significantly decreased LPR were registered in a patient with progressive occlusion of the middle cerebral artery. In a patient with transient ischemic attacks, a slightly reduced LPR and a disproportionally reduced LUGTR were observed before operation. After extra- and intrac-ranial bypass surgery, the LPR became normal, whereas the LUGTR increased but did not achieve normal values.     

Discordance in the anatomical locations between morphological and perfusion changes occurring with the progression of Alzheimer’s disease

Objective

The aim of this study was to clarify the difference between the morphological and perfusion changes occurring with the progression of Alzheimer’s disease (AD).

Methods

The study focused on 37 patients who were clinically diagnosed with AD and were examined by both MRI and perfusion SPECT twice during a 1- to 2-year clinical observation period. Twenty-four of the 37 patients showed a progression of cognitive deterioration during the 1.2(±0.4)-year period of clinical observation (rapidly progressing group: initial mean MMSE score = 23.3; second mean MMSE score = 20.2), while 13 patients showed no apparent progression of cognitive deterioration (slowly progressing group: initial mean MMSE score = 21.2; second mean MMSE score = 22.2). The morphological changes were evaluated using a voxel-based morphometric technique with segmented MRI images. Cerebral perfusion was measured by Tc-99m ECD SPECT. Data analysis was performed by SPM on a MATLAB work space (2007.a).

Results

There was no significant difference in either the perfusion or gray matter density between the rapidly progressing and slowly progressing groups at the initial examination. The rapidly progressing group showed an interval decrease of perfusion in the bilateral parieto-occipital cortex and a decrease of gray matter density in the bilateral temporal and cingulate cortex. The slowly progressing group did not show a significant interval change in either the cerebral perfusion or gray matter density.

Conclusions

These results suggest that rapid symptomatic progression in AD patients accompanies rapid progression of both morphological and perfusion changes, although the regions of the changes differ between them.     

Glucose metabolism in relation to perfusion in patients with ischaemic heart disease

In order to correlate myocardial perfusion and residual metabolism in patients with coronary artery disease, the regional metabolic rate of glucose (rMRGlu) was compared with regional perfusion under glucose loading state (GL) and fasting state (FA). Fluorine-18 deoxyglucose dynamic scan was obtained in ten patients after oral GL and in 16 patients under FA. rMRGlu in seven segments was calculated using Patlak graphic analysis for comparison with normalized percent uptake of nitrogen-13 ammonia at rest in each segment. When perfusion was less than 45%, no segment showed an increase in rMRGlu (0.3 pmol/min/g) under either FA (0/6 segments) or GL (0/8 segments), indicating a certain threshold of perfusion for maintenance of glucose metabolism. When perfusion exceeded 45%, rMRGlu was higher in GL (0.37±0.18 pmol/min/g) than FA (0.15±0.12 pmoVmin/g, P < 0.001) but there was very wide scatter of rMRGlu values under both states. Thus, both myocardium with preserved and myocardium with reduced glucose metabolism may exist when the perfusion exceeds 45%. In conclusion, a minimum threshold of perfusion for the maintenance of glucose metabolism may exist under both FA and GL. Below the threshold, irreversible damage may occur in the myocardium. Above the threshold, quantitative analysis of glucose metabolism should play an important role in differentiating reversibly injured myocardium from necrotic myocardium.     

Relation between wall thickening on gated perfusion SPECT and functional recovery after coronary revascularization in patients with previous myocardial infarction

Purpose This study aimed to evaluate whether wall thickening analysis by gated perfusion single-photon emission computed tomography (SPECT) is useful in predicting functional recovery after revascularization.Methods Forty-one patients with previous myocardial infarction and left ventricular (LV) dysfunction (ejection fraction, EF, 36±6%) who were scheduled for revascularization underwent rest ^99mTc-sestamibi gated SPECT.Results Of 131 akinetic or dyskinetic segments at baseline echocardiography, 82 (63%) recovered after revascularization. Compared with wall thickening analysis, perfusion imaging provided higher sensitivity (78% vs 50%, P<0.0001) and specificity (80% vs 71%, P<0.0005). Among segments with 55% sestamibi uptake (viable), those with detectable wall thickening had a higher likelihood of functional recovery than those with absent wall thickening (95% vs 77%, P<0.05). In segments with improved function, the absence of wall thickening was associated with lower sestamibi activity than was observed when detectable wall thickening was present (58±14% vs 71±13%, P<0.0005). An increase in EF of 5% was detectable in 22 (54%) patients. For the prediction of EF improvement, perfusion imaging provided a higher sensitivity than wall thickening analysis (68% vs 41%, P<0.05), while specificity was not significantly different (68% vs 74%). The prevalence of patients with functional recovery did not change when wall thickening analysis was considered in addition to perfusion status (73% in patients with detectable wall thickening and 70% in those without; P=NS).Conclusion In patients with coronary artery disease, wall thickening analysis by gated perfusion SPECT provides additional information compared with perfusion data for the prediction of segmental functional recovery. However, on a patient basis, wall thickening assessment seems to be of more limited value than perfusion status.     

Immunochemical studies on blood group H and B substances from human hair

Summary Blood group H and B substances were extracted from urea-treated human hair of group O and B individuals, respectively, with methanol-ethyl ether (1:1,v/v) and chloroform-methanol (1:1,v/v). The blood group activities of H and B substances were destroyed by H-decomposing enzyme (-l-fucosidase) fromBacillus fulminans and B-decomposing enzyme (-d-galactosidase) fromClostridium sporogenes Maebashi, respectively. It is concluded therefore that the extract from the hair of group O contained blood group H-active glycolipid with -l-fucose as the non-reducing sugar and the one from group B contained blood group B-active glycolipid with -d-galactose as the non-reducing sugar.     

Brain glucose utilization in systemic lupus erythematosus with neuropsychiatric symptoms: A controlled positron emission tomography study

In contrast to morphological imaging [such as magnetic resonance imaging (MRI) or computed tomography], functional imaging may be of advantage in the detection of brain abnormalities in cases of neuropsychiatric systemic lupus erythematosus (SLE). Therefore, we studied 13 patients (aged 40±14 years, 11 female, 2 male) with neuropsychiatric SLE who met four of the American Rheumatism Association criteria for the classification of SLE. Ten clinically and neurologically healthy volunteers served as controls (aged 40±12 years, 5 female, 5 male). Both groups were investigated using fluorine-18-labelled fluorodeoxyglucose brain positron emission tomography (PET) and cranial MRI. The normal controls and 11 of the 13 patients showed normal MRI scans. However, PET scan was abnormal in all 13 SLE patients. Significant group-to-group differences in the glucose metabolic index (GMI=region of interest uptake/global uptake at the level of the basal ganglia and thalamus) were found in the parieto-occipital region on both sides: the GMI of the parieto-occipital region on the right side was 0.922±0.045 in patients and 1.066±0.081 in controls (P<0.0001, Mann WhitneyU test), while on the left side it was 0.892±0.060 in patients and 1.034±0.051 in controls (P=0.0002). Parietooccipital hypometabolism is a conspicuous finding in mainly MRI-negative neuropsychiatric SLE. As the parieto-occipital region is located at the boundary of blood supply of all three major arteries, it could be the most vulnerable zone of the cerebrum and may be affected at an early stage of the cerebrovascular disease.     

Diagnosis of Alzheimer’s disease using brain perfusion SPECT and MR imaging: which modality achieves better diagnostic accuracy?

Purpose The purpose of this study was to compare the accuracy of MR imaging and brain perfusion single-photon emission tomography (SPECT) in diagnosing Alzheimers disease (AD).Methods The transaxial section display of brain perfusion SPECT, three-dimensional stereotactic surface projection (3D-SSP) SPECT image sets, thin-section MR imaging of the hippocampus and perfusion MR imaging were evaluated in 66 subjects comprising 35 AD patients and 31 subjects without AD. SPECT and MR imaging were visually interpreted by two experts and two novices, and the diagnostic ability of each modality was evaluated by receiver operating characteristic (ROC) analysis.Results In the experts interpretations, there was no significant difference in the area under the ROC curve ( A_z) between 3D-SSP and thin-section MR imaging, whereas the A_z of transaxial SPECT display was significantly lower than that of 3D-SSP (3D-SSP: 0.97, thin-section MR imaging: 0.96, transaxial SPECT: 0.91), and the A_z of perfusion MR imaging was lowest (0.63). The sensitivity and specificity of each modality were, respectively, 80.0% and 96.8% for 3D-SSP, 77.1% and 96.8% for thin-section MR imaging, 60.0% and 93.5% for transaxial SPECT display and 34.3% and 100% for perfusion MR imaging. In the novices interpretations, the A_z, sensitivity and specificity of 3D-SSP were superior to those of thin-section MR imaging.Conclusion Thin-section hippocampal MR imaging and 3D-SSP image sets had potentially equivalent value for the diagnosis of AD, and they were superior to transaxial SPECT display and perfusion MR imaging. For avoidance of the effect of interpreters experience on image evaluation, 3D-SSP appears to be optimal.     

Effect of l-arginine administration on myocardial thallium-201 perfusion during exercise in patients with angina pectoris and normal coronary angiograms

Objectives  We tested the hypothesis that an exogenous supplement of l-arginine could alleviate coronary perfusion abnormality during exercise in patients with angina pectoris and normal coronary arteries. Methods and Results  Twelve patients underwent exercise thallium-201 scintigraphy without medication (control) and after intravenous administration of l-arginine. Exercise time was prolonged in the l-arginine study compared with the control (482 s vs 540 s, P<.05). Tl-201 extent score was improved in the l-arginine study (0.33 vs 0.26, P<.05), and the severity score was also improved (23.7 vs 16.9, P<.05). In 7 of the 12 patients whose Tl-201 redistribution disappeared in the l-arginine study, the percent increase in serum l-citrulline concentration during exercise was larger than that of the remaining 5 patients (18% vs 0.9%, P<.01). The percent reduction in epicardial coronary diameter in response to acetylcholine was also greater in the former group (28.3% vs 11.1%, P<.05). Conclusion  Exogenous l-arginine improved myocardial perfusion during exercise in a subset of patients with angina pectoris and normal coronary arteries, probably by increasing production of nitric oxide.     

Left ventricular diastolic function in type 2 diabetes mellitus is associated with myocardial triglyceride content but not with impaired myocardial perfusion reserve

Purpose:

To study myocardial perfusion reserve and myocellular metabolic alterations indicated by triglyceride content as possible causes of diastolic dysfunction in patients with type 2 diabetes mellitus, preserved systolic function, and without clinically evident coronary artery disease.

Materials and Methods:

Patients with type 2 diabetes mellitus (n = 42) underwent cardiac magnetic resonance (CMR) for quantification of 1) myocardial contractility by strain‐encoded MR (SENC); 2) myocardial triglyceride content by proton magnetic resonance spectroscopy (¹H‐MRS); and 3) myocardial perfusion reserve during pharmacologic hyperemia. Age‐matched healthy volunteers (n = 16) also underwent CMR to acquire normal values for myocardial strain and perfusion reserve.

Results:

Stress CMR procedures were successfully performed in all subjects, and no regional inducible perfusion defects were observed in type 2 diabetes mellitus patients. Diastolic strain rate and myocardial perfusion reserve were significantly impaired in patients with type 2 diabetes mellitus compared to control subjects (P < 0.001 for both). Interestingly, impaired diastolic function in type 2 diabetes mellitus was not associated with impaired myocardial perfusion reserve (r = 0.12, P = NS). Conversely a significant association was observed between diastolic dysfunction and myocardial triglyceride content (r = ?0.71, P < 0.001), which proved to be independent of age, gender, diabetes duration, blood pressure, and fasting blood glucose.

Conclusion:

Myocardial steatosis may represent an early marker of diabetic heart disease, triggering subclinical myocardial dysfunction irrespective of myocardial perfusion reserve. J. Magn. Reson. Imaging 2012;35:804–811. © 2011 Wiley Periodicals, Inc.

     

3D-liver perfusion MRI with the MS-325 blood pool agent: a noninvasive protocol to asses liver fibrosis

Purpose:

To evaluate a 1.5T magnetic resonance imaging (MRI) protocol, including a dedicated acquisition sequence and a postprocessing tool for the quantitative analysis of hepatic tissue perfusion. Estimated perfusion parameters and histological results based on the METAVIR classification were prospectively compared for hepatic fibrosis assessment.

Materials and Methods:

The study protocol was approved by the experimentation Ethics Committee and informed consent was obtained. Sixteen patients (6 women, 10 men; average age, 52.4 ± 14.8 years) with chronic liver diseases were prospectively enrolled after a liver biopsy. MS‐325 (paramagnetic blood pool agent)‐enhanced MRI was performed using a free‐breath 3D‐VIBE T_1w sequence. Image volumes were registered by an automatic rigid method. Liver perfusion was modeled by a dual‐input‐one‐compartment model and quantitative perfusion parameters such as arterial, portal, and total perfusion mean transit time (MTT) and hepatic perfusion index (HPI) were obtained using in‐house developed software.

Results:

Arterial perfusion increased with METAVIR stage, whereas portal perfusion decreased leading to an HPI increase with fibrosis stage. MTT increased with F3, F4. A nonparametric Mann–Whitney test demonstrated that HPI and portal perfusion were relevant in discriminating between advanced and nonadvanced fibrosis, between fibrosis and cirrhosis, then between nonfibrosis and fibrosis (P < 0.01). A strong correlation was found between portal perfusion fall‐off and HPI increase (r = ?0.97; P < 0.001). HPI and portal perfusion were strongly correlated with fibrosis stage (r = 0.83 and ?0.88; P < 0.001, respectively).

Conclusion:

HPI and portal perfusion could be relevant indicators for the clinical follow‐up in patients with chronic liver diseases. J. Magn. Reson. Imaging 2012;35:1380–1387. © 2012 Wiley Periodicals, Inc.

     

Early therapy monitoring with FDG-PET in aggressive non-Hodgkin’s lymphoma and Hodgkin’s lymphoma

This study was designed to determine the value of 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) in the early assessment of therapy response in lymphoma patients. We studied 20 patients with pathologically proven lymphoma, including 17 patients with aggressive non-Hodgkins lymphoma and three patients with Hodgkins lymphoma. All patients underwent whole-body FDG-PET imaging at baseline and after 1–2 cycles of chemotherapy. PET images were analysed visually and quantitatively by calculating the standardised uptake value (SUV). In each patient, we measured the SUV of the tumour demonstrating the highest FDG uptake at baseline study and the SUV of the same tumour after 1–2 cycles of therapy. The achievement of complete response was assessed on the basis of a combination of clinical findings and the results of conventional imaging modalities. Follow-up of progression-free survival (PFS) was obtained for the validation of PET data. Of the 20 patients, ten achieved complete remission at the completion of chemotherapy and the other ten did not respond to chemotherapy. Of the ten responders, four are still in remission (PFS 24–34 months) while the other six have relapsed (PFS 8–16 months). For the prediction of 24-month clinical outcome, visual analysis of PET after 1–2 cycles showed high sensitivity (87.5%) and accuracy (80%) but low specificity (50%). Comparison with the baseline SUVs revealed that the responders showed a significantly greater percent reduction in SUV after 1–2 cycles of therapy as compared with the non-responders (81.2%±9.5% vs 35.0%±20.2%, P<0.001). In addition, using 60% reduction as a cut-off value, the responders were clearly separated from the non-responders, with the exception of one non-responder. In conclusion, when performed early during chemotherapy, FDG-PET may be predictive of clinical outcome and allows differentiation of responders from non-responders in cases of aggressive lymphoma.     

Ictal technetium-99m ethyl cysteinate dimer single-photon emission tomographic findings and propagation of epileptic seizure activity in patients with extratemporal epilepsies

Although ictal single-photon emission tomography (SPET) with technetium-99m ethyl cysteinate dimer (ECD) has a well-established role in the diagnostic evaluation of patients with temporal lobe epilepsy who are being considered for epilepsy surgery, its use in cases of extratemporal epilepsy is still limited. We investigated the influence of the propagation of extratemporal epileptic seizure activity on the regional increase in cerebral blood flow, which is usually associated with epileptic seizure activity. Forty-two consecutive patients with extratemporal epilepsies were prospectively evaluated. All patients underwent ictal SPET studies with simultaneous electroencephalography (EEG) and video recordings of habitual seizures and imaging studies including cranial magnetic resonance imaging and positron emission tomography with 2-[¹⁸F]-fluoro-2 deoxy-d-glucose. Propagation of epilptic seizure activity (PESA) was defined as the absence of hyperperfusion on ictal ECD SPET in the lobe of seizure onset, but its presence in another ipsilateral or contralateral lobe. Observers analysing the SPET images were not informed of the other results. PESA was observed in 8 of the 42 patients (19%) and was ipsilateral to the seizure onset in five (63%) of these eight patients. The time between clinical seizure onset and injection of the ECD tracer ranged from 14 to 61 s (mean 34 s). Seven patients (88%) with PESA had parieto-occipital epilepsy and one patient had a frontal epilepsy. PESA was statistically more frequent in patients with parieto-occipital lobe epilepsies (58%) than in the remaining extratemporal epilepsy syndromes (3%) (P<0.0002). These findings indicate that ictal SPET studies require simultaneous EEG-video recordings in patients with extratemporal epilepsies. PESA should be considered when interpreting ictal SPET studies in these patients. Patients with PESA are more likely to have parieto-occipital lobe epilepsy than seizure onset in other extratemporal regions. Received 14 August and in revised form 31 October 1997     

Myocardial scintigraphy with thallium-201 and technetium-99m-hexakis-methoxyisobutylisonitrile in left bundle branch block: a study in patients with and without coronary artery disease

In left bundle branch block (LBBB) thallium-201 myocardial scintigraphy frequently reveals septal abnormalities in the absence of coronary artery disease (CAD) and gives rise to false-positive results in patients with suspected CAD. It has not yet been clarified which pathophysiological mechanism is responsible for these perfusion abnormalities. A total of 66 patients with constant LBBB were investigated with ²⁰¹T1 or technetium-99m-hexakis-methoxyisobutylisonitrile (MIBI), 62 underwent coronary angiography. Of 12 patients without left anterior descending artery (LAD) or right coronary artery (RCA) stenoses, 11 had a reversible septal activity deficit after ²⁰¹T1 stress injection, whereas 20 of 22 patients without relevant CAD showed a constant stress/rest septal deficit using MIBI. Regarding patients with significant LAD and/or RCA stenoses, both radiopharmaceuticals almost always showed a reversible septal deficit: with ²⁰¹T1 in 15 of 16 individuals and with MIBI in 14 of 15. In 12 patients ²⁰¹T1 was reinjected at rest. In those who had LAD or RCA stenoses (n = 5), early septal activity uptake after stress injection was poorer than that after rest injection; in the absence of CAD (n = 7), septal stress uptake corresponded with that of rest injection. It is concluded that septal perfusion abnormalities in LBBB and the absence of CAD are characterized by an exercise-independent reduction of septal blood flow per mass of viable myocardium and that stress/rest injection protocols of myocardial perfusion tracers are able to differentiate between LBBB with and without CAD.Dedicated to Prof. Dr. Dr. h.c. H. Hundeshagen on the occasion of his 65th birthday Correspondence to: W.H. Knapp     

Diffusion and perfusion correlates of the 18F-MISO PET lesion in acute stroke: pilot study

Purpose

Mapping the ischaemic penumbra in acute stroke is of considerable clinical interest. For this purpose, mapping tissue hypoxia with ¹⁸F-misonidazole (FMISO) PET is attractive, and is straightforward compared to ¹⁵O PET. Given the current emphasis on penumbra imaging using diffusion/perfusion MR or CT perfusion, investigating the relationships between FMISO uptake and abnormalities with these modalities is important.

Methods

According to a prospective design, three patients (age 54–81 years; admission NIH stroke scale scores 16–22) with an anterior circulation stroke and extensive penumbra on CT- or MR-based perfusion imaging successfully completed FMISO PET, diffusion-weighted imaging and MR angiography 6–26 h after stroke onset, and follow-up FLAIR to map the final infarction. All had persistent proximal occlusion and a poor outcome despite thrombolysis. Significant FMISO trapping was defined voxel-wise relative to ten age-matched controls and mapped onto coregistered maps of the penumbra and irreversibly damaged ischaemic core.

Results

FMISO trapping was present in all patients (volume range 18–119 ml) and overlapped mainly with the penumbra but also with the core in each patient. There was a significant (p?≤?0.001) correlation in the expected direction between FMISO uptake and perfusion, with a sharp FMISO uptake bend around the expected penumbra threshold.

Conclusion

FMISO uptake had the expected overlap with the penumbra and relationship with local perfusion. However, consistent with recent animal data, our study suggests FMISO trapping may not be specific to the penumbra. If confirmed in larger samples, this preliminary finding would have potential implications for the clinical application of FMISO PET in acute ischaemic stroke.