Major prognostic impact of persistent microvascular obstruction as assessed by contrast-enhanced cardiac magnetic resonance in reperfused acute myocardial infarction

The aim of this study was to compare the prognostic significance of microvascular obstruction (MO) and persistent microvascular obstruction (PMO) as assessed by cardiac magnetic resonance (CMR) in patients with acute myocardial infarction (AMI). CMR was performed in 184 patients within the week following successfully reperfused first AMI. First-pass images were performed to evaluate extent of MO and late gadolinium-enhanced images to assess PMO and infarct size (IS). Major adverse cardiac events (MACE) were collected at 1-year follow-up. MO and PMO were found in 127 (69%) and 87 (47%) patients, respectively. By using univariate logistic regression analysis, high Global Registry of Acute Coronary Events (GRACE) risk score (odds ratio [OR] 95% confidence interval [CI]: 3.6 [1.8–7.4], p < 0.001), IS greater than 10% (OR [95% CI]: 2.7 [1.1–6.9], p = 0.036), left ventricular ejection fraction less than 40% (OR [95% CI]: 2.4 [1.1–5.2], p = 0.027), presence of MO (OR [95% CI]: 3.1 [1.3–7.3], p = 0.004) and presence of PMO (OR [95% CI]:10 [4.1–23.9], p < 0.001) were shown to be significantly associated with the outcome. By using multivariate analysis, presence of MO (OR [95% CI]: 2.5 [1.0–6.2], p = 0.045) or of PMO (OR [95% CI]: 8.7 [3.6–21.1], p < 0.001), associated with GRACE score, were predictors of MACE. Presence of microvascular obstruction and persistent microvascular obstruction is very common in AMI patients even after successful reperfusion and is associated with a dramatically higher risk of subsequent cardiovascular events, beyond established prognostic markers. Moreover, our data suggest that the prognostic impact of PMO might be superior to MO.     

Detection and characteristics of microvascular obstruction in reperfused acute myocardial infarction using an optimized protocol for contrast-enhanced cardiovascular magnetic resonance imaging

Several cardiovascular magnetic resonance imaging (CMR) techniques are used to detect microvascular obstruction (MVO) after acute myocardial infarction (AMI). To determine the prevalence of MVO and gain more insight into the dynamic changes in appearance of MVO, we studied 84 consecutive patients with a reperfused AMI on average 5 and 104 days after admission, using an optimised single breath-hold 3D inversion recovery gradient echo pulse sequence (IR-GRE) protocol. Early MVO (2 min post-contrast) was detected in 53 patients (63%) and late MVO (10 min post-contrast) in 45 patients (54%; p = 0.008). The extent of MVO decreased from early to late imaging (4.3 ± 3.2% vs. 1.8 ± 1.8%, p < 0.001) and showed a heterogeneous pattern. At baseline, patients without MVO (early and late) had a higher left ventricular ejection fraction (LVEF) than patients with persistent late MVO (56 ± 7% vs. 48 ± 7%, p < 0.001) and LVEF was intermediate in patients with early MVO but late MVO disappearance (54 ± 6%). During follow-up, LVEF improved in all three subgroups but remained intermediate in patients with late MVO disappearance. This optimised single breath-hold 3D IR-GRE technique for imaging MVO early and late after contrast administration is fast, accurate and allows detection of patients with intermediate remodelling at follow-up.     

MRI for the diagnosis of left ventricular apical ballooning syndrome (LVABS)

To compare MRI findings of left ventricular apical ballooning syndrome (LVABS) with those of acute myocardial infarction (AMI). Fifteen patients with a LVABS (group 1) and 25 patients with an AMI (group 2) were explored by MRI within 24 h after admission. Comparison of both groups for the number and location of myocardial segments with abnormal wall motion and abnormal perfusion or delayed enhancement was performed. The number of involved segments was higher in group 1 than in group 2 (p < 0.001). In group 1, segments with abnormal wall motion were distributed in more than one vascular territory in all patients and confined to the medial, distal, and apical regions of the left ventricle. Subendocardial hypoenhancement was observed in 16/25 patients (64%) in group 2 and in none of group 1 (p < 0.001). All patients in group 2 demonstrated delayed-enhancement abnormalities in a vascular distribution, whereas none in group 1 presented this abnormality (p < 0.001). Diffusely distributed segmental wall-motion abnormalities and absence of first-pass perfusion hypoenhancement and of delayed enhancement at MRI help to differentiate LVABS from AMI. In the acute phase or in some difficult cases, cardiac MRI should become routine to confirm the diagnosis of LVABS.     

Clinical safety of cardiac magnetic resonance imaging at 3 T early after stent placement for acute myocardial infarction

The purpose of this study was to prospectively evaluate the safety of cardiac magnetic resonance (CMR) imaging at 3 T performed early (less than 14 days) after bare metal or drug-eluting coronary stent implantation in patients with acute myocardial infarction (AMI). Seventy-two consecutive patients with AMI treated by percutaneous revascularisation with a stent underwent CMR examination with a median delay of 6 days. Patients were followed-up for major adverse cardiac events, during hospitalisation and at 6 months. After CMR imaging, no acute stent thrombosis, death or repeated AMI were recorded at 6-month follow-up. Two symptomatic in-stent restenoses and two silent in-stent restenoses were recorded, at a mean delay of 106 days. In our population, we found a target revascularisation rate of 5.6%. This is consistent with the 6-month event rates after coronary artery stent (CAS) placement for AMI, evaluated by several studies. This preliminary clinical study supports the safety of 3-T CMR imaging performed early after coronary stent placement.     

Clinical and radiological outcomes of acute ischemic stroke patients without angiographic occlusion on digital subtraction angiogram. A pooled analysis of case series

Introduction  Approximately 20–30% of the patients with acute ischemic stroke do not have any occlusion demonstrated on initial digital subtraction angiography (DSA). We sought to determine the risk and rates of cerebral infarction and favorable neurological outcome in this group of acute ischemic stroke patients. Materials and methods  Patients were identified from a prospectively maintained stroke database and from literature search of MEDLINE, PubMed, and Cochrane databases. All patients had initial neurological assessment on National Institutes of Health Stroke Scale (NIHSS). Patients then underwent DSA after initial head computed tomography (CT) scans. Follow-up radiological assessment at 24–72 h was performed with CT and magnetic resonance imaging scans. Association of stroke risk factors with clinical and radiological outcomes was estimated. Results  A total of 81 patients was analyzed (mean age 63 years; 28 were women). The median NIHSS score was 8 (range 2–25). None of the patients received either intravenous or intra-arterial thrombolytic. Cerebral infarction was detected in 62 (76%) of the 81 patients. Twenty-four to 48-h NIHSS was available for 51 patients only. Neurological improvement was observed in 22 (43%) of the 51 patients. Favorable outcome ascertained at 3-month follow-up was seen in 48 (59%) of the 81 patients. After adjusting for age, sex, and baseline NIHSS, male patients [odds ratio (OR) 4.5 (1.4–14.3), p value = 0.01] and patients with age ≥65 [OR 4.3 (1.2–16.2), p value = 0.03] have a higher risk of cerebral infarcts on the follow-up imaging. Similarly, patients who presented with <10 NIHSS had a better 3-month outcome than those with >10 NIHSS [OR 0.21 (0.08–0.61), p value = 0.004]. Conclusion  Ischemic stroke patients without arterial occlusion on DSA have a higher risk of cerebral infarction and disability particularly in men, patients over 65 years of age and with NIHSS ≥10. The cause of infarction may have been arterial obstruction with spontaneous recanalization or small vessel occlusion not visible on DSA.     

Clinical utility of 2-D anatomic measurements in predicting cough-associated headache in Chiari I malformation

Cough-associated headache (CAH) is the most distinctive symptom of patients with Chiari I malformation (CMI) and indicates clinically significant disease. We determined the clinical utility of simple 2D anatomic measurements performed on a PACS workstation by assessing their diagnostic accuracy in predicting CAH in CMI patients. Seventy-two consecutive CMI patients (cerebellar tonsillar herniation > 5 mm) with headache seen by neurosurgeons over 6 years were included. Sagittal T1 images were used by two readers to measure: extent of tonsillar herniation, lengths of the clivus and supra-occiput, McRae and pB-C2 lines, as well as clivus-canal, odontoid retroversion, and skull base angles. Neurosurgery notes were reviewed to determine presence of CAH. Mann-Whitney test was used to compare measurements between patients with and without CAH. Predictive accuracy was assessed by receiver operating characteristic (ROC) curve. 47/72 (65.3%) CMI patients reported CAH. Tonsillar herniation with CAH (10.2 mm, 7–14 mm; median, interquartile range) was significantly greater than those without CAH (7.9 mm, 6.3–10.9 mm; p = 0.02). Tonsillar herniation ≥ 10 mm showed sensitivity and specificity of 51% and 68%, and tonsillar herniation > 14 mm showed sensitivity and specificity of 30% and 100%, respectively, for predicting CAH. Other 2D measurements showed no statistically significant differences. Among the 2D measurements used, only the extent of tonsillar herniation is different between CMI patients with and without CAH. Although CMI is diagnosed with tonsillar herniation of only 5 mm, we found that a much higher extent of herniation is needed to be predictive of CAH.     

Comparison of the prognostic value of SPECT after nitrate administration and metabolic imaging by PET in patients with ischaemic left ventricular dysfunction

Purpose We compared the prognostic value of ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT) after nitrate administration and positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG) in patients with ischaemic left ventricular (LV) dysfunction. Methods Eighty-nine patients with previous myocardial infarction and LV dysfunction (LV ejection fraction 33 ± 10%) underwent ^99mTc-tetrofosmin SPECT under control conditions (baseline) and after sublingual administration of 10 mg of isosorbide dinitrate (nitrate). Within 1 week, all patients underwent PET imaging with ¹⁸F-FDG. Four patients were excluded because of inadequate FDG uptake caused by severe diabetes. Follow-up data were obtained by phone contact with patients and by review of hospital or physicians’ records. Cardiac death, myocardial infarction and late revascularisation for unstable angina were considered as events. Follow-up data were not available in three patients. Follow-up was 96% complete at a mean period of 29 ± 19 months. Results At baseline SPECT, 59 (72%) patients had evidence of viable myocardium, while 23 did not. Of these latter patients, 12 (52%) demonstrated viable myocardium after nitrate and 13 (56%) had preserved metabolic activity. Cardiac events (cardiac death, myocardial infarction and late revascularisation for unstable angina) occurred in 24 (29%) patients. Event-free survival was similar in patients with and patients without viable myocardium at baseline SPECT (p = 0.8). In contrast, event-free survival was lower in patients with viable myocardium at nitrate SPECT and PET compared to those without viable myocardium (both p<0.05). Conclusion In patients with ischaemic LV dysfunction, the prognostic value of SPECT imaging after nitrate is comparable to that of PET metabolic imaging.     

Estimate of myocardial salvage in late presentation acute myocardial infarction by comparing functional and perfusion abnormalities in predischarge gated SPECT

Purpose We hypothesized that, because of persistent stunning, the extent of post-treatment functional abnormalities detected using gated single-photon emission computed tomography (SPECT) could be representative of the initial risk area in acute myocardial infarction (AMI) treated by reperfusion therapy. Materials and methods In 48 AMI patients, we acquired two ^99mTc-sestamibi gated SPECT studies (at admission with tracer injection before treatment and at discharge 5 to 10 days later). We assessed the myocardial salvage defined by the admission minus predischarge summed rest score, and we compared it with the value obtained by subtracting the extent of perfusion defect from the extent of wall motion or wall thickening abnormalities in predischarge gated SPECT. Myocardial salvage was expressed as salvage index (salvaged myocardium divided by initial risk area). Results There was a good correlation between summed rest score salvage index and wall motion (Spearman’s ρ = 0.754, p < 0.0001) or wall thickening salvage index (Spearman’s ρ = 0.798, p < 0.0001). The wall thickening salvage index was able to classify correctly the patients that had a summed rest score salvage index ≥ 0.10 with 73% sensitivity, 88% specificity, and 83% accuracy. The wall motion salvage index was highly sensitive (91%) but poorly specific (13%, p < 0.002 vs wall thickening salvage index) and less accurate (69%, p < 0.05 vs wall thickening salvage index). Conclusions ^99mTc-sestamibi gated SPECT allows assessing myocardial salvage using only post-treatment data. The salvage index derived using wall thickening as surrogate of admission perfusion defect correlates well with the salvage index measured by comparing pre- and post-treatment perfusion defects.     

Diagnostic utility and clinical implication of late gadolinium enhancement cardiac magnetic resonance for detection of catheter associated right atrial thrombus

PurposeTo use delayed enhancement cardiac magnetic resonance (DE-CMR) as a reference standard to evaluate the prevalence and predictors of right atrial (RA) thrombus.MethodsIn this retrospective study, 130 cancer patients with central venous catheters undergoing CMR from August 2012–January 2018 were included. CMR (cine-CMR and DE-CMR) and echocardiography were interpreted for RA thrombus blinded to other imaging results and clinical data. RA thrombus properties including the number of discrete masses, size, total thrombus area, and perimeter were also assessed. Cine-CMR was also used to quantify cardiac structure and function as markers of RA thrombus. Student's t-test was used to assess continuous variables; chi-square or Fisher's exact test were used to assess categorical variables.Results31/130 (24%) patients had RA thrombus on DE-CMR. Echocardiography (attained in 64% of the study population) demonstrated moderate sensitivity and specificity (75%, 90% respectively) in relation to DE-CMR; cine-CMR performance was higher (sensitivity 90%, specificity 98%). Patients with and without RA thrombus had similar right-sided structure/function and cancer diagnosis. Catheter depth approached significance in patients with RA thrombus (p = 0.05). 13% of patients with RA thrombus had concomitant pulmonary embolism within 60 days of CMR vs. 2% of patients without RA thrombus (p = 0.03). Embolic events were independent of RA thrombus size (p = 0.66).ConclusionMorphologic imaging by cine-CMR and echocardiography provide limited diagnostic utility for RA thrombus as established by DE-CMR tissue characterization. Catheter-associated RA thrombus occurs independently of right-sided structure or function and is associated with clinical embolic events and catheter depth.     

Prognostic significance of stress myocardial ECG-gated perfusion imaging in asymptomatic patients with diabetic chronic kidney disease on initiation of haemodialysis

Purpose  Diabetic patients with chronic kidney disease (CKD) frequently develop cardiac events within several years of the initiation of haemodialysis. The present study assesses the prognostic significance of stress myocardial ECG-gated perfusion imaging (MPI) in patients with diabetic CKD requiring haemodialysis. Methods  Fifty-five asymptomatic patients with diabetic stage V CKD and no history of heart disease scheduled to start haemodialysis were enrolled in this study (56 ± 11 years old; 49 with type 2 diabetes mellitus). All patients underwent ²⁰¹Tl stress ECG-gated MPI 1 month before or after the initiation of haemodialysis to assess myocardial involvement. We evaluated SPECT images using 17-segment defect scores graded on a 5-point scale, summed stress score (SSS) and summed difference scores (SDS). The patients were followed up for at least 2 years (42 ± 15 months) to determine coronary intervention (CI) and heart failure (HF) as soft events and acute myocardial infarction (AMI) and all causes of deaths as hard events. Results  The frequencies of myocardial ischaemia, resting perfusion defects, low ejection fraction and left ventricular (LV) dilatation were 24, 20, 29 and 49%, respectively. Ten events (18%) developed during the follow-up period including four CI, one HF, one AMI and four sudden deaths. Multivariate Cox analysis selected SDS (p = 0.0011) and haemoglobin A_1c (HbA_1c) (p = 0.0076) as independent prognostic indicators for all events. Conclusion  Myocardial ischaemia, in addition to glycaemic control, is a strong prognostic marker for asymptomatic patients with diabetic CKD who are scheduled to start haemodialysis. Stress MPI is highly recommended for the management and therapeutic stratification of such patients.     

Prognostic value of high-field proton magnetic resonance spectroscopy in patients presenting with clinically isolated syndromes suggestive of multiple sclerosis

Introduction The aim of this study was to determine the prognostic value of metabolic alterations in the normal-appearing white matter (NAWM) of patients presenting with clinically isolated syndromes (CIS) suggestive of multiple sclerosis (MS) with special regard to the prediction of conversion to definite MS. Methods Using a 3T whole-body MR system, a multisequence conventional MRI protocol and single-voxel proton MR spectroscopy (PRESS, repetition time 2000 ms, echo times 38 ms and 140 ms) of the parietal NAWM were performed in 25 patients presenting with CIS at baseline and in 20 controls. Absolute concentrations of N-acetyl-aspartate (tNAA), myo-inositol (Ins), choline (Cho) and creatine (tCr) as well as metabolite ratios were determined. Follow-up including neurological assessment and conventional MRI was performed 3–4 and 6–7 months after the initial event. Results Nine patients converted to definite MS during the follow-up period. Compared to controls, those patients who converted to MS also showed significantly lower tNAA concentrations in the NAWM (−13.4%, P = 0.002) whereas nonconverters (−6.5%, P = 0.052) did not. The Ins concentration was 20.2% higher in the converter group and 1.9% higher in the nonconverter group, but these differences did not reach significance. No significant differences could be observed for tCr and Cho in either patient group. Conclusion Axonal damage at baseline in patients presenting with CIS was more prominent in those who subsequently converted to definite MS in the short term follow-up, indicating that tNAA might be a sufficient prognostic marker for patients with a higher risk of conversion to early definite MS.     

Nitrate-enhanced gated SPECT in patients with primary angioplasty for acute myocardial infarction: evidence of a reversible and nitrate-sensitive impairment of myocardial perfusion

Purpose Reperfusion of myocardial infarction (MI) leads to a reversible dysfunction of coronary vessels. We hypothesised that vasodilating drugs such as nitrates might improve sestamibi uptake within viable areas of recently reperfused MI, thereby enhancing prediction of subsequent improvements in perfusion and contractility. This study was aimed at assessing nitrate-enhanced sestamibi gated SPECT after MI reperfusion. Methods Twenty-nine patients underwent rest followed by nitrate sestamibi gated SPECT at 9 ± 3 days after primary angioplasty for acute MI and at follow-up, 4–10 months later. Four MBq/kg of ^99mTc-sestamibi was injected at rest, and 12 MBq/kg after nitroglycerin spray. Results Follow-up improvements were documented for both perfusion (P+) and contractility (C+) in 18% of the 180 initially abnormal segments, in neither perfusion (P−) nor contractility (C−) in 44%, in contractility only (C+P−) in 16% and in perfusion only (C−P+) in 22%. Perfusion improvement was related to lower sestamibi uptake on baseline rest SPECT (P+: 42 ± 15% vs P−: 50 ± 15%, p = 0.001) and, moreover, to a higher increase between rest and nitrate uptake (P+: +9.5 ± 6.5% vs P−: +2.0 ± 5.9%, p < 0.001). Contractility improvement was related to sestamibi uptake on baseline nitrate SPECT (C+: 58 ± 15% vs C−: 38 ± 16%, p < 0.001), a variable enhancing the prediction provided by sestamibi uptake at rest (p < 0.05). Conclusion The improvement in perfusion which is documented in the months following MI reperfusion is predicted by initial nitrate enhancement of sestamibi uptake, suggesting a mechanism of reversible vascular injury. In this particular setting, sestamibi uptake is a better predictor of contractility recovery when determined after nitrate administration rather than under conventional resting conditions.     

Diagnostic value of late gadolinium-enhanced MRI and first-pass dynamic MRI for predicting functional recovery in patients after acute myocardial infarction

Purpose The aim of this study was to determine the comparative diagnostic values of late gadolinium-enhanced magnetic resonance imaging (MRI) and first-pass dynamic MRI for predicting functional recovery of regional myocardial contraction in patients early after acute myocardial infarction. Materials and methods First-pass and late-enhanced MRI were performed in 18 patients 5.5 ± 2.5 days after the onset of myocardial infarction. Images analysis was performed using a 12-segment model. Regional systolic wall thickening (SWT) was measured on cine-MRI obtained 273 ± 130 days later. Results Late-enhanced MRI revealed hyperenhancement in all patients, whereas hypoenhancement on first-pass MRI was observed in 67% (12/18) of the patients. The area under the receiver operating characteristics curve was 0.86 for late-enhanced MRI and 0.74 for first-pass MRI (P = 0.27). First-pass MRI was useful for predicting functional recovery of the segments that showed hyperenhancement of >50% of tissue on late-enhanced MRI. In these segments, preserved SWT was observed in 15 of 33 segments (45%) with first-pass hypoenhancement of ≤50% of tissue, but in only 2 of 22 segments (9%) with first-pass hypoenhancement of >50% of tissue. Conclusion Whereas the diagnostic capability of first-pass MRI alone is limited, complementary use of first-pass MRI can enhance the diagnostic performance of late-enhanced MRI because hypoenhancement during first-pass imaging is more specific to nonviable myocardium. An abstract of this article was presented at the Japan Radiological Society spring meeting in 2002     

Prognostic study of risk stratification among Japanese patients with ischemic heart disease using gated myocardial perfusion SPECT: J-ACCESS study

Background Although the prognostic value of myocardial perfusion imaging using gated single photon emission computed tomography (SPECT) for predicting major cardiac events has been evaluated, little is known about the relevance of this procedure to the Japanese population. Methods A total of 4,031 consecutive Japanese patients with suspected or confirmed ischemic heart diseases were registered at 117 hospitals in the Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT investigation. Gated stress/rest myocardial perfusion SPECT was performed and the patients were followed up for 3 years. Segmental perfusion scores and quantitative gated SPECT results were calculated. Major cardiac events were defined as cardiac death, nonfatal myocardial infarction, and severe heart failure. Results During the 3-year follow-up, cardiac death (n = 57) and nonfatal myocardial infarction (n = 39) occurred in 96 patients (2.4%/3 years) when hard events were the endpoints. When severe heart failure was included as an endpoint, major cardiac events that developed in 175 patients (4.3%/3 years) comprised cardiac death (n = 45), nonfatal myocardial infarction (n = 37), and severe heart failure (n = 93). Normal and severely abnormal summed stress score values were associated with low (2.31%/3 years) and high (9.21%/3 years) rates of major cardiac events, respectively. Rates of major cardiac events were significantly higher in patients with ejection fraction (EF) <45% than in those with EF 45% or higher (16.55 vs 2.94%/3 years; P < 0.001). The incidence of major cardiac events within 3 years was also significantly higher among patients with high end-systolic volumes. The major event rates were similar among nondiabetic patients with and diabetic patients without prior myocardial infarction at 5.06% and 5.73%/3 years, respectively. Conclusion Cardiac event rates were significantly lower in the Japanese than in the USA and European populations. However, large myocardial perfusion defects and decreased cardiac function, as well as diabetes mellitus, could be predictors of high event rates and, thus, beneficial for risk stratification of Japanese patients with ischemic heart diseases. Financial support: Japan Cardiovascular Research Foundation     

Whole-body MRI at 1.5 T and 3 T compared with FDG-PET-CT for the detection of tumour recurrence in patients with colorectal cancer

The purpose of this study was to assess the diagnostic accuracy of whole-body MRI (WB-MRI) at 1.5 T or 3 T compared with FDG-PET-CT in the follow-up of patients suffering from colorectal cancer. In a retrospective study, 24 patients with a history of colorectal cancer and suspected tumour recurrence underwent FDG-PET-CT and WB-MRI with the use of parallel imaging (PAT) for follow-up. High resolution coronal T1w-TSE and STIR sequences at four body levels, HASTE imaging of the lungs, contrast-enhanced T1w- and T2w-TSE sequences of the liver, brain, abdomen and pelvis were performed, using WB-MRI at either 1.5 T (n = 14) or 3 T (n = 10). Presence of local recurrent tumour, lymph node involvement and distant metastatic disease was confirmed using radiological follow-up within at least 5 months as a standard of reference. Seventy seven malignant foci in 17 of 24 patients (71%) were detected with both WB-MRI and PET-CT. Both investigations concordantly revealed two local recurrent tumours. PET-CT detected significantly more lymph node metastases (sensitivity 93%, n = 27/29) than WB-MRI (sensitivity 63%, n = 18/29). PET-CT and WB-MRI achieved a similar sensitivity for the detection of organ metastases with 80% and 78%, respectively (37/46 and 36/46). WB-MRI detected brain metastases in one patient. One false-positive local tumour recurrence was indicated by PET-CT. Overall diagnostic accuracy for PET-CT was 91% (sensitivity 86%, specificity 96%) and 83% for WB-MRI (sensitivity 72%, specificity 93%), respectively. Examination time for WB-MRI at 1.5 T and 3 T was 52 min and 43 min, respectively; examination time for PET-CT was 103 min. Initial results suggest that differences in accuracy for local and distant metastases detection using FDG-PET-CT and WB-MRI for integrated screening of tumour recurrence in colorectal cancer depend on the location of the malignant focus. Our results show that nodal disease is better detected using PET-CT, whereas organ disease is depicted equally well by both investigations.     

Effects of percutaneous transluminal angioplasty on muscle BOLD-MRI in patients with peripheral arterial occlusive disease: preliminary results

The purpose was to evaluate the effect of percutaneous transluminal angioplasty (PTA) of the superficial femoral artery (SFA) on the blood oxygenation level-dependent (BOLD) signal change in the calf musculature of patients with intermittent claudication. Ten patients (mean age, 63.4 ± 11.6 years) with symptomatic peripheral arterial occlusive disease (PAOD) caused by SFA stenoses were investigated before and after PTA. Patients underwent BOLD-MRI 1 day before and 6 weeks after PTA. A T2*-weighted single-shot multi-echo echo-planar MR-imaging technique was applied. The BOLD measurements were acquired at mid-calf level during reactive hyperaemia at 1.5 T. This transient hyperperfusion of the muscle tissue was provoked by suprasystolic cuff compression. Key parameters describing the BOLD signal curve included maximum T2* (T2*_max), time-to-peak to reach T2*_max (TTP) and T2* end value (EV) after 600 s of hyperemia. Paired t-tests were applied for statistic comparison. Between baseline and post-PTA, T2*_max increased from 11.1 ± 3.6% to 12.3 ± 3.8% (p = 0.51), TTP decreased from 48.5 ± 20.8 s to 35.3 ± 11.6 s (p = 0.11) and EV decreased from 6.1 ± 6.4% to 5.0 ± 4.2% (p = 0.69). In conclusion, BOLD-MRI reveals changes of the key parameters T2*_max, TTP, and EV after successful PTA of the calf muscles during reactive hyperaemia.     

Prediction of functional recovery after revascularization using quantitative gated myocardial perfusion SPECT: a multi-center cohort study in Japan

Backgrounds  Prediction of left ventricular functional recovery is important after myocardial infarction. The impact of quantitative perfusion and motion analyses with gated single-photon emission computed tomography (SPECT) on predictive ability has not been clearly defined in multi-center studies. Methods  A total of 252 patients with recent myocardial infarction (n = 74) and old myocardial infarction (n = 175) were registered from 25 institutions. All patients underwent resting gated SPECT using ^99mTc-hexakis-2-methoxy-isobutyl isonitrile (MIBI) and repeated the study after revascularization after an average follow-up period of 132 ± 81 days. Visual and quantitative assessment of perfusion and wall motion were performed in 5,040 segments. Results  Non-gated segmental percent uptake and end-systolic (ES) percent uptake were good predictors of wall motion recovery and significantly differed between improved and non-improved groups (66 ± 17% and 55 ± 18%, p < 0.0001 for non-gated; 64 ± 16% and 51 ± 17% for ES percent uptake, p < 0.0001). The area under the curve of receiver operating characteristics curve for non-gated percent uptake, ES percent uptake, end-diastolic percent uptake and visual perfusion defect score was 0.70, 0.71, 0.61, and 0.56, respectively. Sensitivity and specificity of percent uptake were 68% and 64% for non-gated map and 80% and 52% for ES percent uptake map. An optimal threshold for predicting segmental improvement was 63% for non-gated and 52% for ES percent uptake values. Conclusion  Segmental ^99mTc-MIBI uptake provided a useful predictor of wall motion improvement. Application of quantitative approach with non-gated and ES percent uptake enhanced predictive accuracy over visual analysis particularly in a multi-center study.     

Acute myocarditis in a rat model: late gadolinium enhancement with histopathological correlation

The aim of the current study was to use an established animal model of autoimmune myocarditis and to judge the ability of cardiovascular MRI (CMR) in quantitatively measuring the extent of myocardial involvement compared with histopathological measurement of severity and extent. Experimental autoimmune myocarditis (EAM) was induced in 10 male Lewis rats. On day 21, all animals were investigated by CMR to measure the extent of late gadolinium enhancement (LGE). Subsequently, histopathological evaluation of the entire heart was performed. All animals of the experimental group fulfilled histopathological criteria of myocarditis, revealing necrosis in seven of eight cases. At reduced heart rate, area of LGE correlated highly with histologically proven area of myocarditis (r = 0.80–0.87, p < 0.05). LGE was mainly located in the anterior (range 50–62.5%) and lateral (range 62.5–75%) left ventricular wall and septum (range 25–50%) with a midwall to subepicardial accentuation. The LGE pattern found by CMR can be regarded as suggestive of EAM. With cellular necrosis being the main mechanism for LGE we were able to show high correlations between CMR examination results and histopathologically proven areas of myocarditis. Thus we think the current animal model can provide the opportunity for further fundamental research into myocarditis.     

Determinants and impact of microvascular obstruction in successfully reperfused ST-segment elevation myocardial infarction. Assessment by magnetic resonance imaging

Microvascular obstruction (MVO) is an important and independent determinant of post-infarct remodeling. Fifty-two patients with a successfully reperfused ST-segment elevation acute myocardial infarction (MI) were studied with MRI in the first week and at 4 months post-infarction. On early (i.e., 2–5 min) post-contrast MRI, MVO was detected in 32 patients with an MVO to infarct ratio of 36.3 ± 24.9%. On late (i.e., 10–25 min) post-contrast MRI, MVO was detected in only 27 patients, with an MVO to infarct ratio of 15.9 ± 13.9%. MVO infarcts (n = 32) were associated with higher cardiac enzymes (troponin I, P = 0.016), and lower pre-revascularization thrombolysis in myocardial infarction (TIMI) flow (P = 0.018) than non-MVO infarcts (n = 20). Infarct size was larger in MVO infarcts (25.0 ± 14.3 g) than non-MVO infarcts (12.5 ± 7.9 g), P = 0.0007. Systolic wall thickening in the infarct and peri-infarct area, and left ventricular (LV) ejection fraction (EF) were worse in MVO (46.1 ± 7.2%) than non-MVO infarcts (50.5 ± 6.6%, P = 0.038). At 4 months, MVO infarcts showed more adverse remodeling and lack of functional improvement, whereas non-MVO infarcts improved significantly (LV EF at 4 months, MVO, 47.5 ± 7.8%, P = 0.31; non-MVO, 55.2 ± 10.3%, P = 0.0028). In the majority of patients with successfully reperfused ST-segment elevation MI, MVO is observed, whose present and maximal extent can be best evaluated on early post-contrast MRI. Presence of MVO is associated with more extensive infarctions, and characterized by greater adverse LV remodeling and lack of functional recovery.     

Intraindividual comparison of myocardial delayed enhancement MR imaging using gadobenate dimeglumine at 1.5 T and 3 T

For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at 1.5 T and 3 T. Fifteen minutes after injection of contrast agent (0.1 mmol gadobenate dimeglumine per kg body weight), inversion recovery gradient recalled echo (IR-GRE) sequences were acquired (1.5 T/3 T: TR 11.0/9.9 ms, TE 4.4/4.9 ms, flip 30°/30°, slice thickness 6/6 mm) to assess myocardial viability. Two observers rated image quality (Wilcoxon signed rank test). Quantification of hyperenhanced myocardium and standardized SNR/CNR measurements were performed (Student’s t test). There was no significant difference with respect to image quality (1.5 T/3 T: 3.5/3.3, p = 0.34, reader 1; 2.4/2.7, p = 0.12, reader 2) and infarction size (760 ± 566/828 ± 677 mm² at 1.5 T, 808 ± 639/826 ± 726 mm² at 3 T, reader 1/reader 2, p > 0.05). Mean SNR in hyperenhanced/normal myocardium was 19.2/6.2 at 1.5 T and 29.5/8.8 at 3 T (p < 0.05). Mean CNR was 14.3 at 1.5 T and 26.0 at 3 T (p < 0.05). Delayed enhancement MR imaging at 3 T is a robust procedure yielding superior tissue contrast at 3 T compared with 1.5 T which is, however, not reflected by increased image quality.