Feasibility of noise-reduction reconstruction technology based on non-local-mean principle in SiPM-PET/CT.

Quantitative values of positron emission tomography (PET) images using non-local-mean in a silicon photomultiplier (SiPM)-PET/computed tomography (CT) system with phantom and clinical images. The evaluation was conducted on a National Electrical Manufacturers Association body phantom with micro-spheres (4, 5, 6, 8, 10, 13 mm) and clinical images using the SiPM-PET/CT system. The signal-to-background ratio of the phantom was set to 4, and all PET image data was obtained and reconstructed using three-dimensional ordered subset expectation maximization, time-of-flight, point-spread function, and a 4-mm Gaussian filter (GF) and clear adaptive low-noise method (CaLM) in mild, standard, and strong intensities. The evaluation included the standardized uptake value (SUV), percent contrast (QH), coefficient of variation of the background area (CVbackground) clinical imaging for SUV of lung nodules, liver signal-to-noise ratio (SNR), and visual evaluation. SUVmax for 8-mm sphere in phantom images at 2 min for GF and CaLM (mild, standard, strong) were 2.11, 2.32, 2.02, and 1.72; the QH, 8 mm was 27.33 %, 27.47 %, 21.81 %, and 16.09 %; and CVbackground was 12.78, 11.35, 7.86, and 4.71, respectively. CaLM demonstrated higher SUVmax in clinical images than GF for all lung nodule sizes. The average SUVmax for nodules with a diameter of ≤ 1 cm were 5.9 ± 2.4, 9.9 ± 4.9, 9.9 ± 5.0, and 9.9 ± 5.0 for GF and CaLM-mild, standard, and strong intensities, respectively. Liver SNRs were higher for CaLM (mild, standard, strong) compared to GF, with increasing CaLM intensity causing higher liver SNR. CaLM-mild and standard demonstrated suitability for diagnosis in visual evaluation.

Dataset of calcified plaque condition in the stenotic coronary artery lesion obtained using multidetector computed tomography to indicate the addition of rotational atherectomy during percutaneous coronary intervention.

Our data shows the regional coronary artery calcium scores (lesion CAC) on multidetector computed tomography (MDCT) and the cross-section imaging on MDCT angiography (CTA) in the target lesion of the patients with stable angina pectoris who were scheduled for percutaneous coronary intervention (PCI). CAC and CTA data were measured using a 128-slice scanner (Somatom Definition AS+; Siemens Medical Solutions, Forchheim, Germany) before PCI. CAC was measured in a non-contrast-enhanced scan and was quantified using the Calcium Score module of SYNAPSE VINCENT software (Fujifilm Co. Tokyo, Japan) and expressed in Agatston units. CTA were then continued with a contrast-enhanced ECG gating to measure the severity of the calcified plaque condition. We present that both CAC and CTA data are used as a benchmark to consider the addition of rotational atherectomy during PCI to severely calcified plaque lesions.

Preoperative T staging of urinary bladder cancer: efficacy of stalk detection and diagnostic performance of diffusion-weighted imaging at 3T.

PURPOSE: We evaluated the ability of diffusion-weighted imaging (DWI) at 3 tesla for diagnosing T stage and detecting stalks in bladder cancer. METHODS: In total, 39 consecutive patients with bladder tumors underwent magnetic resonance (MR) imaging that included T2-weighted imaging (T2WI) and DWI using a 3T MR scanner. Two radiologists interpreted T2WI plus DWI and T2WI for diagnosis of T stage and for detection of stalks. We used McNemar's test to examine differences in diagnostic performance and Fisher's exact test to evaluate differences in stalk detection frequency. RESULTS: Specificity and accuracy in differentiating T1 tumors from T2 to T4 tumors were significantly better with T2WI plus DWI (83% [20/24] and 85% [33/39]) than T2WI (50% [12/24] and 67% [26/39]; P = 0.02), and accuracy for diagnosing tumor stage was significantly better with T2WI plus DWI (82% [32/39]) than T2WI alone (59% [23/39]; P = 0.03). The observers identified stalks in 11 tumors by T2WI (48% [11/23]) and 17 by DWI (74% [17/23]) (P < 0.03). CONCLUSION: DWI at 3T was superior to T2WI for evaluating the T stage of bladder cancer, particularly in differentiating T1 tumors from those T2 or higher, and in detecting stalks of papillary bladder tumors.

Utility of apparent diffusion coefficients in the evaluation of solid renal tumors at 3T.

PURPOSE: We assessed the usefulness of apparent diffusion coefficients (ADCs) for solid renal tumor imaging using diffusion-weighted magnetic resonance imaging (DWI) at 3T. METHODS: This retrospective study assessed ADCs of 31 patients with renal tumors that were imaged using preoperative DWI. DWI was performed with the b values of 50, 500, and 1000 s/mm(2), using a 3T magnetic resonance imaging (MRI) system (MAGNETOM Trio, 3T, Siemens Healthcare, Erlangen, Germany). The ADC map was calculated using the b values of 50 and 1000 s/mm(2). ADCs of the different tumors were compared according to the Tukey-Kramer test. RESULTS: The tumors were diagnosed as clear cell renal cell carcinoma (RCC; n = 20), papillary RCC (n = 1), infiltrating urothelial carcinoma (UC) of the kidney (n = 4), cystic RCC (n = 1), poorly differentiated carcinoma (n = 1), and angiomyolipoma (AML; n = 4). The mean ADC of clear cell RCC was significantly higher than that of infiltrating UC of the kidney (1.423 vs. 0.931 × 10(-3) mm(2)/s; P < 0.05), and the mean ADC of AML was significantly lower than that of clear cell RCC (0.674 vs. 1.423 × 10(-3) mm(2)/s; P < 0.01). CONCLUSION: ADCs used in DWI at 3T may be useful for differentiation of different types of solid renal tumors.

Reversible T-wave inversions and neurogenic myocardial stunning in a patient with recurrent stress-induced cardiomyopathy.

A 72-year-old female was diagnosed as a stress-induced cardiomyopathy from apical ballooning pattern of left ventricular dysfunction without coronary artery stenosis after the mental stress. ECG showed the transient T-wave inversions after the ST-segment elevations. By the mental stress after 1 year, she showed a transient dysfunction with similar ECG changes again. T-wave inversions recovered earlier, and cardiac sympathetic dysfunction showed a lighter response corresponding to the less severe dysfunction than those after the first onset. Wellens' ECG pattern was associated with the degree of neurogenic myocardial stunning with sympathetic hyperinnervation caused by mental stress.

A combination of P wave electrocardiography and plasma brain natriuretic peptide level for predicting the progression to persistent atrial fibrillation: comparisons of sympathetic activity and left atrial size.

PURPOSE: Development of atrial fibrillation (AF) is complexly associated with electrical and structural remodeling and other factors every stage of AF development. We hypothesized that P wave electrocardiography with an elevated brain natriuretic peptide (BNP) level would be associated with the progression to persistence from paroxysmal AF. METHODS: P wave electrocardiography such as a maximum P wave duration (MPWD) and dispersion by 12-leads ECG, heart/mediastinum (H/M) ratio by delayed iodine-123 metaiodobenzylguanidine scintigraphic imaging, left ventricular ejection fraction (LVEF), and left atrial dimension (LAD) by echocardiography, and plasma BNP level were measured to evaluate the electrical and structural properties and sympathetic activity in 71 patients (mean ± standard deviation, age: 67 ± 13 years, 63.4 % males) with idiopathic paroxysmal AF. RESULTS: Over a 12.9-year follow-up period, AF developed into persistent AF in 30 patients. A wider MPWD (>129 ms) (p = 0.001), wider P wave dispersion (>60 ms) (p = 0.001), LAD enlargement (>40 mm) (p = 0.001), higher BNP level (>72 pg/mL) (p = 0.002), lower H/M ratio (≤2.7) (p = 0.025), and lower LVEF (≤60 %) (p = 0.035) were associated with the progression to persistent AF, and the wide MPWD was an independently powerful predictor of the progression to persistent AF with a hazard ratio (HR) of 5.49 [95 % confidence interval (CI) 2.38-12.7, p < 0.0001] after adjusting for potential confounding variables, such as age and sex. The combination of wide MPWD and elevated BNP level was additive and incremental prognostic power with 13.3 [2.16-13, p < 0.0001]. CONCLUSION: The wide MPWD with elevated BNP level was associated with the progression to persistent AF.

Usefulness of severe cardiac sympathetic dysfunction to predict the occurrence of rapid atrial fibrillation in patients with Wolff-Parkinson-White syndrome.

Atrial fibrillation (AF) can be a potentially life-threatening arrhythmia when it conducts rapidly through the accessory pathway, which was not predicted by the noninvasive method. We evaluated the cardiac sympathetic activity for predicting the occurrence of AF in patients with Wolff-Parkinson-White (WPW) syndrome. Iodine-123 metaiodobenzylguanidine scintigraphy was performed under stable sinus rhythm conditions at rest <1 week before an electrophysiologic study (EPS) to assess the sympathetic activity using the heart/mediastinum (H/M) ratio in 45 consecutive patients with WPW who had a history of supraventricular tachycardia (mean ± SD, age: 47 ± 17 years, 42.2% women). The study also included 15 normal healthy volunteers (56 ± 17 years, 40% women). The H/M ratio was lower in patients with WPW syndrome than in the normal control group, and in the 15 patients with AF induced during EPS than in the 30 patients without AF (p <0.0001). The sensitivity of H/M ratio ≤2.8 for predicting the AF induced during EPS was 75% in 12 of 16 patients, and the specificity was 89.7% in 26 of 29 patients. The H/M ratio was positively correlated with anterograde effective refractory period (r = 0.514, p <0.0001). The sensitivity of H/M ratio ≤2.75 for predicting the AF with a short anterograde effective refractory period (≤250 ms) was 91.7% in 11 of 12 patients, and the specificity was 90.9% in 30 of 33 patients. In conclusion, the severe cardiac sympathetic dysfunction was associated with the occurrence of AF, particularly in those with rapid AF and in patients with WPW syndrome.

Diagnostic accuracy of ultra-high-b-value 3.0-T diffusion-weighted MR imaging for detection of prostate cancer.

PURPOSE: To investigate the diagnostic accuracy of 3.0-T diffusion-weighted imaging (DWI) for detection of prostate cancer by using different b-values. METHODS: Seventy-three patients underwent magnetic resonance imaging (MRI) at 3.0 T. Three MRI sets were reviewed by two radiologists: MRI and DWI (b = 500 s/mm(2)) (protocol A), MRI and DWI (b = 1000 s/mm(2)) (protocol B), and MRI and DWI (b = 2000s/mm(2)) (protocol C). Areas under the receiver operating characteristic curve (AUCs) were calculated. RESULTS: The mean of the AUCs in protocol C was larger than those in protocol A and in protocol B (P<.05). CONCLUSION: DWI (b = 2000s/mm(2)) at 3.0 T can improve the diagnostic accuracy for detection of prostate cancer.

Association between left and right atrial remodeling with atrial fibrillation recurrence after pulmonary vein catheter ablation in patients with paroxysmal atrial fibrillation: a pilot study.

BACKGROUND: Left atrial (LA) remodeling is a factor in atrial fibrillation (AF) recurrence after pulmonary vein catheter ablation (CA), but right atrium (RA) remodeling has not been investigated for possible associations to AF recurrence. METHODS AND RESULTS: Using 64-slice multidetector computed tomography, RA and LA volumes were measured 3-dimensionally before CA in 65 patients with initially proven idiopathic paroxysmal AF (mean age, 60±10 years, 81.5% men). The CA procedure was guided by CARTO Merge atrial electroanatomic mapping. Sixteen patients (24.6%) had AF recurrence within the 6-month period after the CA. The recurrence was associated with a large RA volume [odds ratio, 1.04; 95% confidence interval (CI), 1.02 to 1.07, P<0.0001], a large LA volume with 1.04 [95% CI, 1.01 to 1.06, P=0.002], and low LA mean voltage with 1.03 [95% CI, 1.01 to 1.05, P=0.002]. After adjustment for potential confounding variables, RA and LA volumes remained predictive of AF recurrence. Large atrial volumes (mL) (RA ≥87 or LA ≥99) predicted AF recurrence (sensitivity of RA volume: 81.3% in 13 of 16 patients with AF recurrence; specificity: 75.5% in 37 of 49 patients without AF recurrence; sensitivity of LA volume: 81.3% in 13 of 16 patients with AF recurrence; specificity: 69.4% in 34 of 49 patients without AF recurrence), and the combined estimate of both atrial volumes was incremental and additive prognostic power (sensitivity: 75% in 12 of 16 patients with AF recurrence; specificity: 93.9% in 46 of 49 patients without AF recurrence). CONCLUSIONS: Both LA and RA remodeling are equally associated with post-CA AF recurrence.

Iodine-123 mIBG Imaging for Predicting the Development of Atrial Fibrillation.

OBJECTIVES: we investigated whether cardiac sympathetic nervous system (SNS) activity measured by iodine-123 meta-iodobenzylguanidine ((123)I-mIBG) imaging would be associated with both the occurrence of heart failure (HF) and the transit to permanent atrial fibrillation (AF) in patients with paroxysmal AF. BACKGROUND: atrial fibrillation occurs suddenly and transiently and can persist, and results in the occurrence of HF. An important feature of AF and HF is their propensity to coexist not only because they share antecedent risk factors, but also because the one may directly predispose the heart to the other. However, a useful modality for predicting the occurrences of both those has not been established in patients with paroxysmal AF. METHODS: the (123)I-mIBG scintigraphy was performed to evaluate cardiac SNS activity presented as the heart/mediastinum ratio in 98 consecutive patients (age 66 ± 13 years, 63.3% male) with idiopathic paroxysmal AF and preserved left ventricular ejection fraction (≥ 50%). RESULTS: during 4 ± 3.6 years of follow-up, the transit to permanent AF was associated with the occurrence of HF (34.3% in 12 of 35 patients with permanent AF vs. 6.3% in 4 of 63 patients without, p < 0.0001). Lower heart/mediastinum ratio and lower left ventricular ejection fraction were the independent predictors of the transit to permanent AF with adjusted hazard ratios of 3.44 (95% confidence interval [CI]: 1.9 to 6.2, p < 0.0001) and 1.04 (95% CI: 1.01 to 1.08, p = 0.014). Further, these factors and higher plasma brain natriuretic peptide concentration were the independent predictors of the occurrence of HF with permanent AF, with adjusted hazard ratios of 5.08 (95% CI: 1.5 to 17.5, p = 0.011), 1.11 (95% CI: 1.03 to 1.19, p = 0.004), and 1.004 (95% CI: 1.001 to 1.008, p = 0.014). CONCLUSIONS: cardiac SNS abnormality was associated with the occurrence of both HF and permanent AF in paroxysmal AF patients, and (123)I-mIBG imaging may be a useful modality for predicting the development of AF.

MRI of the neck at 3 Tesla using the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) (BLADE) sequence compared with T2-weighted fast spin-echo sequence.

PURPOSE: To evaluate motion artifacts, tissue contrasts, and lesion detectability in the neck with the periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) (BLADE) technique. MATERIALS AND METHODS: A total of 46 patients referred for MRI of the neck were included in a comparison of T2-weighted BLADE (T2W-BLADE) sequence and T2W fast spin-echo (T2W-FSE) sequence. All examinations were performed at 3T using the same parameters. Two observers evaluated unlabelled images for motion artifacts, the preferred image quality, and lesion detectability. Region of interest (ROI)-based quantitative measurements were performed to assess tissue contrasts. The frequency of occurrence of the different assessed artifacts and the lesion detectability was tested using McNemar's test. Tissue contrasts were compared using the Wilcoxon paired test. Reader agreement was assessed using kappa test. RESULTS: T2W-BLADE showed less ghosting and pulsation artifacts than T2W-FSE (P < 0.01). T2W-BLADE images were rated as better than or equal to T2W-FSE images in majority cases (93.5%; kappa = 0.64). There was not significant difference in tissue contrasts between T2W-BLADE and T2W-FSE. A total of 32 lesions were present in 32 patients and equally well seen on T2W-BLADE and T2W-FSE. CONCLUSION: T2W-BLADE can reduce motion artifacts and provide tissue contrasts and lesion detectability equivalent to T2W-FSE.

Sympathetic dysfunction of systemic right ventricle in congenitally corrected transposition of the great arteries.

We evaluate the systemic right ventricle (SRV) failure of congenitally corrected transposition of the great arteries using the scintigraphic studies in a case with 32-year-old male who improved the heart failure by the use of beta-adrenergic blockers. The myocardial perfusion sympathetic nervous system activity mismatch with preserved coronary flow and wall thickness indicates a distinctive feature as SRV cardiomyopathy, suggesting the importance of recovery of SRV sympathetic dysfunction for improving the prognosis.

Significance of cardiac sympathetic nervous system abnormality for predicting vascular events in patients with idiopathic paroxysmal atrial fibrillation.

PURPOSE: Neuronal system activity plays an important role for the prognosis of patients with atrial fibrillation (AF). Using (123)I metaiodobenzylguanidine ((123)I-MIBG) scintigraphy, we investigated whether a cardiac sympathetic nervous system (SNS) abnormality would be associated with an increased risk of vascular events in patients with paroxysmal AF. METHODS: (123)I-MIBG scintigraphy was performed in 69 consecutive patients (67 + or - 13 years, 62% men) with paroxysmal AF who did not have structural heart disease. SNS integrity was assessed from the heart to mediastinum (H/M) ratio on delayed imaging. Serum concentration of C-reactive protein (CRP) was measured before (123)I-MIBG study. RESULTS: During a mean of 4.5 + or - 3.6 years follow-up, 19 patients had myocardial infarction, stroke or heart failure (range: 0.2-11.5 years). SNS abnormality (H/M ratio <2.7) and high CRP (> or = 0.3 mg/dl) were associated with the vascular events (58.3% in 14 of 24 patients with SNS abnormality vs 11.1% in 5 of 45 patients without SNS abnormality, p < 0.0001, 52.4% in 11 of 21 patients with high CRP vs 16.7% in 8 of 48 patients without high CRP, p < 0.0001). After adjustment for potential confounding variables such as age, left atrial dimension and left ventricular function, SNS abnormality was an independent predictor of vascular events with a hazard ratio of 4.1 [95% confidence interval (CI): 1.3-12.6, p = 0.014]. Further, SNS abnormality had an incremental and additive prognostic power in combination with high CRP with an adjusted hazard ratio of 4.1 (95% CI: 1.5-10.9, p = 0.006). CONCLUSION: SNS abnormality is predictive of vascular events in patients with idiopathic paroxysmal AF.

Thallium-201 and I-123 beta-methyl iodophenyl-pentadecanoic acid dual isotope single photon emission computed tomography for evaluating reperfusion injury after successful reperfusion therapy.

We report a reperfusion injury after rotational coronary atherectomy (RA) in a 66-year-old man with coronary artery disease. Submaximal exercise with thallium-201 single photon emission computed tomography (SPECT) imaging before reperfusion showed partially reversible perfusion defects in the apex and reversible perfusion defects in the anteroseptal area. Thallium-201 and I-123 beta-methyl iodophenyl-pentadecanoic acid (BMIPP) dual isotope SPECT was performed 5 days before and 1 hour after RA, and 1 month after RA. SPECT images at 1 hour after recovery of no reflow phenomenon after RA revealed enlargement of the defect sizes on thallium-201 and BMIPP uptakes in the anteroseptal area including the apex compared with those before RA. The defect size of thallium-201 uptake was progressively improved on 5 hour delayed redistribution imaging and 1 month after reperfusion compared with that of BMIPP uptake. In conclusion, the changes for the worse of thallium-201 uptake and fatty acid metabolism immediately after the no reflow phenomenon may indicate an injured membrane integrity with altered myocardial metabolism rather than myocardial ischemia. Thallium-201 and I-123 BMIPP dual isotope SPECT is useful for evaluating reperfusion injury after successful reperfusion therapy in a patient with acute coronary syndrome.

Technetium-99m pyrophosphate/thallium-201 dual-isotope SPECT imaging predicts reperfusion injury in patients with acute myocardial infarction after reperfusion.

PURPOSE: Microcirculatory failure after reperfusion is clinically indicated to cause reperfusion injury whereas excessive intracellular calcium ion overload is experimentally proved as a key mechanism of reperfusion injury. We hypothesized that technetium-99m ((99m)Tc) pyrophosphate (Tc-PYP) uptake in injured but viable infarct-related myocardium with preserved myocardial perfusion after reperfusion estimated by thallium-201 ((201)Tl) uptake would be associated with final functional recovery. METHODS: Dual-isotope Tc-PYP/(201)Tl single-photon emission computed tomography (SPECT) was performed 2 days after successful reperfusion therapy in patients with first acute myocardial infarction, and 50 patients (63 +/- 13 years old, female 22%) with preserved (201)Tl uptakes of > or = 50% in reperfused myocardium was followed for 1 month. Tc-PYP uptake was assessed as the heart-to-sternum (H/S) ratio. Two-dimensional echocardiography was also performed 2 days and 1 month after reperfusion to evaluate functional recovery. RESULTS: High Tc-PYP uptake, defined as the H/S ratio > or = 0.81, was predictive of chronic phase no functional recovery (73.7% in 14 of 19 patients with high uptake vs 16.1% in five of 31 patients without those, p < 0.0001). After adjustment for potential confounding variables, including electrocardiographic persistent ST segment elevation at 1 h after reperfusion, high Tc-PYP uptake remained independently predictive of no functional recovery with odds ratio of 8.7 (95% confidential interval = 2 to 38.7; p = 0.005). CONCLUSION: High Tc-PYP uptake in reperfused but viable infarct-related myocardium was a powerful predictor of no functional recovery, which may reflect excessive intracellular calcium ion overload caused by reperfusion injury. Tc-PYP/(201)Tl dual-isotope SPECT imaging can provide prognostic information after reperfusion.

[MR arthrographic findings of SLAP lesion type V].

PURPOSE: The purpose of this study was to determine the findings of MR arthrography of the shoulder and to assess the role of MR arthrography in the diagnosis of superior labrum anterior to posterior (SLAP) lesion type V. METHODS AND MATERIALS: Two radiologists retrospectively reviewed fat-suppressed T1-weighted MR arthrography images of six patients who were diagnosed with SLAP lesion type V by arthroscopy. Each imaging plane, including the transverse, oblique coronal, oblique sagittal, and oblique transverse in abductor external rotation (ABER) position were evaluated for the following three findings: tear of the superior labrum at biceps tendon insertion, Bankart lesion, and continuity of the two former findings. RESULTS: Tear of the superior labrum was shown in all patients on oblique coronal images. Bankart lesion was noted in five patients on the transverse images and in four on the oblique sagittal images. On the oblique transverse images in ABER position, Bankart lesion was shown in all patients. The continuity of the two former findings was noted in three patients on the ABER positioned images. Therefore, three patients could be diagnosed as having SLAP lesion type V by MR arthrography in our series. CONCLUSION: It is difficult to detect all three findings of SLAP lesion type V in one imaging plane, however, a combination of multi-directional images may increase the feasibility of MR arthrography in diagnosing SLAP lesion type V.