Left atrial vortex flow and its relationship with left atrial functions in patients with congenital heart disease.

BACKGROUND: Four-dimensional flow magnetic resonance imaging (MRI) enables blood flow visualization. The absence of left atrial vortex flow (LAVF) has been implicated in the development of thrombus formation and arrhythmias. However, the clinical relevance of this phenomenon in patients with congenital heart disease (CHD) remains unclear. This study aimed to unravel the relationship of LAVF with left atrial functions in patients with CHD. RESULTS: Twenty-five participants who underwent cardiac MRI examinations were included (8 postoperative patients with CHD aged 17-41 years and 17 volunteers aged 21-31 years). All participants were in sinus rhythm. Four-dimensional flow MRI (velocity encoding 100 cm/s) assessed the presence of LAVF, and its relationship with left atrial function determined by transthoracic echocardiography was explored. LAVF was detected in 16 patients. Upon classification of the participants based on the presence or absence of LAVF, 94% of participants in the LAVF group were volunteers, while 78% of those in the without LAVF group were postoperative patients. Participants without LAVF had a significantly lower left atrial ejection fraction (61% vs. 70%, p = 0.019), reservoir (32% vs. 47%, p = 0.006), and conduit (22% vs. 36%, p = 0.002) function than those with LAVF. CONCLUSIONS: LAVF occurred during the late phase of ventricular systole, and left atrial reservoir function may have contributed to its occurrence. Many postoperative patients with CHD experienced a loss of LAVF. LAVF may indicate early left atrial dysfunction resulting from left atrial remodeling.

Liver T1/T2 values with cardiac MRI during respiration.

BACKGROUND: Assessing the hepatic status of children with CHD is very important in the post-operative period. This study aimed to assess the usefulness of paediatric liver T1/T2 values and to evaluate the impact of respiration on liver T1/T2 values. METHODS: Liver T1/T2 values were evaluated in 69 individuals who underwent cardiac MRI. The mean age of the participants was 16.2 ± 9.8 years. Two types of imaging with different breathing methods were possible in 34 participants for liver T1 values and 10 participants for liver T2 values. RESULTS: The normal range was set at 620-830 msec for liver T1 and 25-40 ms for liver T2 based on the data obtained from 17 healthy individuals. The liver T1/T2 values were not significantly different between breath-hold and free-breath imaging (T1: 769.4 ± 102.8 ms versus 763.2 ± 93.9 ms; p = 0.148, T2: 34.9 ± 4.0 ms versus 33.6 ± 2.4 ms; p = 0.169). Higher liver T1 values were observed in patients who had undergone Fontan operation, tetralogy of Fallot operation, or those with chronic viral hepatitis. There was a trend toward correlation between liver T1 values and liver stiffness (R = 0.65, p = 0.0004); and the liver T1 values showed a positive correlation with the shear wave velocity (R = 0.62, p = 0.0006). CONCLUSIONS: Liver T1/T2 values were not affected by breathing patterns. Because liver T1 values tend to increase with right heart overload, evaluation of liver T1 values during routine cardiac MRI may enable early detection of future complications.

Comparison of myocardial T1 mapping during breath-holding and free-breathing.

BACKGROUND: T1 mapping is a recently developed imaging analysis method that allows quantitative assessment of myocardial T1 values obtained using MRI. In children, MRI is performed under free-breathing. Thus, it is important to know the changes in T1 values between free-breathing and breath-holding. This study aimed to compare the myocardial T1 mapping during breath-holding and free-breathing. METHODS: Thirteen patients and eight healthy volunteers underwent cardiac MRI, and T1 values obtained during breath-holding and free-breathing were examined and compared. Statistical differences were determined using the paired t-test. RESULTS: The mean T1 values during breath-holding were 1211.1 ± 39.0 ms, 1209.7 ± 37.4 ms, and 1228.9 ± 52.5 ms in the basal, mid, and apical regions, respectively, while the mean T1 values during free-breathing were 1165.1 ± 69.0 ms, 1103.7 ± 55.8 ms, and 1112.0 ± 81.5 ms in the basal, mid, and apical regions, respectively. The T1 values were lower during free-breathing than during breath-holding in almost all segments (basal: p = 0.008, mid: p < 0.001, apical: p < 0.001). The mean T1 values in each cross section were 3.1, 7.8, and 7.7% lower during free-breathing than during breath-holding in the basal, mid, and apical regions, respectively. CONCLUSIONS: We found that myocardial T1 values during free-breathing were about 3-8% lower in all cross sections than those during breath-holding. In free-breathing, it may be difficult to assess myocardial T1 values, except in the basal region, because of underestimation; thus, the findings should be interpreted with caution, especially in children.

Assessment of the Efficiency of Non-Invasive Diagnostic Imaging Modalities for Detecting Myocardial Ischemia in Patients Suspected of Having Stable Angina.

This study aimed to assess and compare the efficiency of non-invasive imaging modalities in detecting myocardial ischemia in patients with suspected stable angina as easy-to-understand indices. Our study included 1000 patients with chest pain and possible stable myocardial ischemia. The modalities to be assessed were cardiac magnetic resonance imaging (CMRI), single-photon emission computed tomography, positron emission computed tomography (PET), stress echocardiography, and fractional flow reserve derived from coronary computed tomography angiography (FFRCT). As a simulation study, we assumed that all five imaging modalities were performed on these patients, and a decision tree analysis was conducted. From the results, the following efficiencies were assessed and compared: (1) number of true positive (TP), false positive (FP), false negative (FN), and true negative (TN) test results; (2) positive predictive value (PPV); (3) negative predictive value (NPV); (4) post-test probability; (5) diagnostic accuracy (DA); and (6) number needed to diagnose (NND). In the basic settings (pre-test probability: 30%), PET generated the highest TP (267) and NPV (95%, 95% confidence interval (CI): 93-96%). In contrast, CMRI produced the highest TN (616), PPV (76%, 95% CI: 71-80%), and DA (88%, 95% CI: 86-90%) and the lowest NND (1.33, 95% CI: 1.24-1.47). Although FFRCT generated the highest TP (267) and lowest FN (33), it generated the highest FP (168). In terms of detecting myocardial ischemia, compared with the other modalities, PET and CMRI were more efficient. The results of our study might be helpful for both patients and medical professionals associated with their examination.

[Optimization of External Driver Amplitude in Magnetic Resonance Elastography of the Liver: Relationship between Appropriate External Driver Amplitude and Indicators of Physical Constitution].

PURPOSE: Magnetic resonance elastography (MRE) of the liver was performed to examine the appropriate external driver amplitude according to the physique of the subject and the index useful for determining the physique. METHODS: For 60 subjects who underwent MRE examination, we measured the unmeasurable elastic modulus area in the liver based on the stiffness map obtained from MRE. The external driver amplitude with the smallest unmeasurable elastic modulus area was taken as the appropriate external driver amplitude for the subject. The receiver operating characteristic (ROC) analysis was performed on the indicators of physical constitution (abdominal depth, waist circumference, body weight and body mass index (BMI) ) and external driver amplitude of 30%, 50% and 70%. BMI was the most appropriate tool for the comparison of indicators of physical constitution. RESULT: The appropriate external driver amplitude was 30% when the cutoff value of BMI was less than 25.3 kg/m², 70% when it was 31.0 kg/m² or more, and 50% when it was between them. CONCLUSION: It is considered that an accurate elastic modulus can be obtained by setting an appropriate indicator of physical constitution and external driver amplitude according to physique in MRE.

[Evaluation of Efficiencies on the Gadoxetic Acid-enhanced MRI for Preoperative Assessment of Liver Metastases from Colorectal Carcinoma].

THE AIMS OF OUR STUDY WERE: 1) to evaluate efficiencies of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) for preoperative assessment of liver metastases from colorectal carcinoma, and 2) to compare them with other diagnostic imaging modalities. The subjects of the analysis were outpatients with advanced colorectal cancer who are at risk of developing liver metastases (initial setting: pre-test probability=20%). At initial setting, we performed a decision analysis to calculate numbers of true positive (TP), false negative (FN), false positive (FP) and true negative (TN) test results per 1000 patients of Gd-EOB-MRI and other imaging modalities (conventional contrast agent-enhanced MRI, contrast-enhanced CT and 18F-FDG PET/CT). From the result of decision analysis, we calculated the cost of detection per one patient with liver metastases (detection cost). Also, we calculated positive predictive value (PPV) and negative predictive value (NPV). Moreover, these values were defined as efficiencies in this study. In the initial setting, number of TP, FN, FP TN results and detection cost of Gd-EOB-MRI were 197, 3, 40, 760, and 224,032.8 Japanese Yen, respectively. Also, PPV and NPV were 83.1% and 99.7%, respectively. In comparison with other imaging modalities, efficiencies of Gd-EOB-MRI were superior to them, except detection cost. We consider that the efficiencies of Gd-EOB-MRI, which we had assessed are easy to understand and useful when they are used for explanation to patients.

Three-dimensional conformal arc radiotherapy using a C-arm linear accelerator with a computed tomography on-rail system for prostate cancer: clinical outcomes.

BACKGROUND: We report the feasibility and treatment outcomes of image-guided three-dimensional conformal arc radiotherapy (3D-CART) using a C-arm linear accelerator with a computed tomography (CT) on-rail system for localized prostate cancer. METHODS AND MATERIALS: Between 2006 and 2011, 282 consecutive patients with localized prostate cancer were treated with in-room CT-guided 3D-CART. Biochemical failure was defined as a rise of at least 2.0 ng/ml beyond the nadir prostate-specific antigen level. Toxicity was scored according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. RESULTS: A total of 261 patients were analyzed retrospectively (median follow-up: 61.6 months). The median prescribed 3D-CART dose was 82 Gy (2 Gy/fraction, dose range: 78-86 Gy), and 193 of the patients additionally received hormonal therapy. The 5-year overall survival rate was 93.9 %. Among low-, intermediate-, and high-risk patients, 5-year rates of freedom from biochemical failure were 100, 91.5 and 90.3 %, respectively. Rates of grade 2-3 late gastrointestinal and genitourinary toxicities were 2.3 and 11.4 %, respectively. No patient experienced late grade 4 or higher toxicity. CONCLUSIONS: In-room CT-guided 3D-CART was feasible and effective for localized prostate cancer. Treatment outcomes were comparable to those previously reported for intensity-modulated radiotherapy.

The prognostic value of normal stress cardiovascular magnetic resonance imaging.

OBJECTIVES: The purpose of our study was to determine the prognostic value of normal stress cardiovascular magnetic resonance imaging (CMR) by a systematic literature review and meta-analysis. METHODS: A comprehensive literature search of published studies through November 2011 in MEDLINE database and Cochrane Library, regarding prognostic value of stress CMR in patients with known or suspected coronary artery disease, was performed. RESULTS: Ultimately, we identified 11 studies. The summary relative risk ratio for major adverse cardiac events was 0.50 (95% confidence interval [CI], 0.44-0.58) for normal cine CMR and 0.09 (95% CI, 0.02-0.35) for normal perfusion CMR. The summary relative risk ratio for hard cardiac events was 0.36 (95% CI, 0.16-0.8) for normal cine CMR and 0.22 (95% CI, 0.07-0.66) for normal perfusion CMR. CONCLUSIONS: Normal stress CMR for patients known or suspected of having coronary artery disease has good prognostic value in predicting cardiac events.

Comparison of the cost-effectiveness of stress myocardial perfusion MRI and SPECT in patients with suspected coronary artery disease.

Our aim in this study was to perform a cost-effectiveness analysis (CEA) to compare myocardial perfusion magnetic resonance imaging (p-MRI) and single photon emission computed tomography (SPECT) in the Japanese setting. The CEA of p-MRI and SPECT was performed from the payer's perspective. The subjects were outpatients who had chest pain, had no history of myocardial infarction, and showed normal or equivocal stress electrocardiogram findings. The costs of imaging techniques and treatments were assessed with the use of reimbursements of medical fees from Japanese healthcare insurance for the year 2007. Clinical effectiveness was defined in terms of the percent correct diagnosis of coronary artery disease (CAD). Data from published studies provided probabilities for the CEA, including the sensitivity and specificity of each imaging modality. We evaluated the cost-effectiveness ratio (CER) of p-MRI and SPECT using a decision tree model and compared the two. The CERs for diagnosis of CAD by p-MRI and SPECT were 1,988.2 and 2,582.0 Japanese Yen (JPY), respectively. The CERs for diagnosis and treatment of CAD by p-MRI and SPECT were 7,066.1 and 7,172.2 JPY, respectively. At a pre-test likelihood of CAD of 20-70 %, the CERs for diagnosis of CAD by p-MRI and SPECT were 1,476.8-3,364.3 and 2,107.3-3,957.7 JPY, respectively. For outpatients with chest pain, p-MRI had good clinical effectiveness and cost-effectiveness compared with SPECT. In the management of patients with suspected CAD, p-MRI is as useful as SPECT.

[Comparsion with myocardial perfusion MRI and myocardial perfusion SPECT in the diagnostic performance of coronary artery disease: a meta-analysis].

We compared the diagnostic abilities of stress myocardial perfusion MRI (myocardial perfusion MRI) and myocardial perfusion SPECT, using a meta-analysis method. We investigated the diagnostic abilities of MRI and SPECT in similar subject groups in reports written in English or Japanese. The reports to be used for analysis were selected according to a "screening standard," which was established in advance. After consolidating the data from the selected reports, we compared (1) the integrated odds ratio, (2) the point estimation values of sensibility/specificity, and (3) the summary ROC curve. For the analysis, six reports were selected (subjects: 153, coronary-artery target sites: 447). Meta-analysis revealed that the diagnostic ability of myocardial perfusion MRI was superior to that of myocardial perfusion SPECT regarding each of the parameters (1)-(3). This is considered to be supportive evidence of the usefulness of myocardial perfusion MRI.

Evaluation of normal fatty replacement of the thymus with chemical-shift MR imaging for identification of the normal thymus.

PURPOSE: To clarify the influences of age and gender on normal fatty replacement of the thymus in childhood, adolescence, and early adulthood using chemical-shift MRI. MATERIALS AND METHODS: A total of 95 normal subjects (52 males and 43 females, mean age = 15.6 years, range = 7-25 years) who underwent chemical-shift MRI of the thymus were assessed prospectively. Signal intensity loss (SIL) of the thymus was determined by dividing the thymus/muscle ratio on the opposed-phase image by that on the in-phase image. We evaluated SIL for its correlation with age and gender, and assessed SIL of the thymus with uncommon morphological features. RESULTS: A significant correlation was found between SIL and age (r = 0.750, P < 0.001). There was no significant difference in SIL between the genders. No significant SIL was identified in any of the subjects aged 10 years or less. However, significant SIL was found in 70.8% of those aged 11-20 years, 100% of those aged 21 years or more, and 46.2% of subjects with uncommon morphological features of the thymus. CONCLUSION: Chemical-shift MRI can depict physiologic fatty infiltration within the normal thymus in subjects over 11 years of age. It is crucial to correlate these normal age-related findings with clinical cases in order to avoid misinterpretation.

Focus on the conditions of resection and reconstruction in gastric cancer. What extent of resection and what kind of reconstruction provide the best outcomes for gastric cancer patients?

To assess the roles of the extent of gastric resection and duodenal food passage reconstruction in gastric cancer, we examined a consecutive series of 1,061 patients who underwent total or partial (proximal and distal) gastrectomies with or without duodenal food passage reconstruction between August of 1974 and January of 2002, and received gastrectomies with D2-3 lymph node dissection. Patients who underwent distal or proximal gastrectomy were found to have significantly better survival rates than those who underwent total gastrectomy in stages 1A (10-year survival: 86.6 and 78.9 vs. 61.6%), 2 (56.5 and 65.6 vs. 34.4%), 3A (45.9 and 33.3 vs. 15.2%), and 4 (5-year survival rates: 23.7 and 50.0 vs. 7.1%). Additionally, patients with duodenal food passage reconstruction or double tract reconstruction also showed significantly better survival rates than those without duodenal food reconstruction in stages 1A (10-year survival: 86.4 and 82.5 vs. 61.7%), 1B (69.9 and 90.6 vs. 54.1%), 2 (60.5 and 63.3 vs. 16.5%), and 3A (39.9 and 47.4 vs. 23.1%). In multivariate analysis, the independent prognostic factors were age at operation, depth of tumor, duodenal food passage reconstruction, and lymph node metastasis. Our results indicate that both the extent of gastric resection and duodenal food passage reconstruction were important factors in the outcome of gastric cancer patients, and that surgeons should perform minimal gastric resection with preservation of the duodenal food passage when the gastric stump is tumor-free.

Characterization of the normal and hyperplastic thymus on chemical-shift MR imaging.

OBJECTIVE: We designed our study to prospectively assess a potential role for chemical-shift MR imaging in identifying a thymus that has not been completely replaced by fat tissue. CONCLUSION: The thymic tissue revealed homogeneous decrease in intensity on opposed-phase MR images relative to that seen on in-phase images in 15 healthy volunteers and two patients with hyperplastic thymus. Chemical-shift MR imaging may be useful in identifying normal thymic tissue and the hyperplastic thymus in early adulthood.