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Background: 99mTc-sestamibi myocardial perfusion imaging (MIBI) washout is associated with myocardial mitochondrial damage in patients with a successful percutaneous coronary intervention (PCI) following acute myocardial infarction (AMI) and may predict the functional improvement of the left ventricle in follow-ups. Objectives: This study aimed to investigate the clinical efficacy of 99mTc-MIBI washout in patients with AMI by measuring the mean defect area based on 99mTc-MIBI myocardial perfusion-single photon emission computed tomography (MP-SPECT) rest imaging in early and delayed phases and comparing it with the defect area based on 99mTc-MIBI MP-SPECT adenosine stress imaging based on a two-day rest/stress protocol. Patients and Methods: This study was conducted on 29 consecutive patients with AMI (23 males and 6 females; mean age, 71 ± 8.4 years), who underwent MP-SPECT using a standard two-day rest/stress protocol. The rest 99mTc-MIBI MP-SPECT images were acquired in the early phase at one hour after the injection of 99mTc-MIBI and in the delayed phase at three hours after the early phase. The total perfusion deficit (TPD) score for SPECT was measured to compare the defect area between the rest-early phase, rest-delayed phase, and post-stress imaging conditions. Results: Based on the results, the post-stress TPD score was significantly lower than the rest-delayed phase score (TPD: 22.2% ± 14.3% vs. 27.8% ± 14.0%; P < 0.001). Also, the rest-early phase score was significantly lower than the rest-delayed phase score (TPD: 21.5% ± 14.9% vs. 27.8% ± 14.0%; P < 0.001). However, no significant difference was observed between the post-stress score and the rest-early phase score. Conclusion: The combination of rest-early phase, delayed phase, and post-stress 99mTc-MIBI imaging using a two-day protocol after AMI reperfusion was a clinically useful method, which could identify residual ischemia and predict the left ventricular function improvement in the chronic phase of disease while reducing the exposure dose.

Purpose: To compare the diagnostic value of mono-exponential, bi-exponential, and stretched exponential diffusion-weighted imaging (DWI) for differentiating benign and malignant hepatic lesions. Methods: This prospective study was approved by our Institutional Review Board and the patients provided written informed consent. Magnetic resonance imaging was acquired for 56 patients with suspected liver disease. This identified 90 focal liver lesions with a maximum diameter >10 mm, of which 47 were benign and 43 were malignant. Using home-built software, two radiologists measured the DWI parameters of hepatic lesions for three models: the apparent diffusion coefficient (ADC) from a mono-exponential model; the true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) from a bi-exponential model; and the distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) from a stretched exponential model. The parameters were compared between benign and malignant hepatic lesions. Results: ADC, D, D*, f, and DDC values were significantly lower for malignant hepatic lesions than for benign lesions (P < 0.0001–0.03). Although logistic regression analysis demonstrated that DDC was the only statistically significant parameter for differentiating benign and malignant lesions (P = 0.039), however, the areas under the receiver operating characteristic curve for differentiating benign and malignant lesions were comparable between ADC (0.98) and DDC (0.98) values. Conclusion: DDC values obtained from the stretched exponential model could be also used as a quantitative imaging biomarker for differentiating benign and malignant hepatic lesions, however, the diagnostic performance was comparable with ADC values.

Velocity and angular distributions of photofragment CO2+ ions produced from mass-selected (CO2)2+ at 532 nm excitation were observed in an ion imaging experiment. The velocity distribution was assigned to two components, fast and slow velocity components, which was consistent with the previous study by Bowers et al. The anisotropy parameters of the angular distributions for the fast and slow velocity components were experimentally determined to be βfast = 1.52 ± 0.14 and βslow = 0.46 ± 0.10, respectively. In the theoretical approach, potential energy surfaces (PESs) of (CO2)2+ were calculated along two coordinates, the intermolecular distance and mutual orientations of the CO2 monomers. In addition, molecular dynamics simulations were performed. The visible transition of the most stable staggered structure of (CO2)2+ was attributed to 2Ag ← 2Bu by an excited state calculation. On the PES of the state, a potential well was found in which the two CO2 monomers lay side by side to each other, in addition to a repulsive slope along the intermolecular distance. The results of the simulations confirmed that the fragment CO2+ ions with fast velocity and large anisotropy originated from the rapid dissociation of (CO2)2+ on the repulsive slope. Meanwhile, the fragment CO2+ ions with slow velocity and small anisotropy were expected to emerge from statistical dissociation after large amplitude libration of CO2 molecules which was caused by the potential well in the excited state PES.

To evaluate the use of deep-learning-based image reconstruction (DLIR) algorithms in dynamic contrast-enhanced computed tomography (CT) of the abdomen, and to compare the image quality and lesion conspicuity among the reconstruction strength levels.This prospective study included 59 patients with 373 hepatic lesions who underwent dynamic contrast-enhanced CT of the abdomen. All images were reconstructed using four reconstruction algorithms, including 40% adaptive statistical iterative reconstruction-Veo (ASiR-V) and DLIR at low, medium, and high-strength levels (DLIR-L, DLIR-M, and DLIR-H, respectively). The signal-to-noise ratio (SNR) of the abdominal aorta, portal vein, liver, pancreas, and spleen and the lesion-to-liver contrast-to-noise ratio (CNR) were calculated and compared among the four reconstruction algorithms. The diagnostic acceptability was qualitatively assessed and compared among the four reconstruction algorithms and the conspicuity of hepatic lesions was compared between5 and ≥5 mm lesions.The SNR of each anatomical structure (p0.0001) and CNR (p0.0001) were significantly higher in DLIR-H than the other reconstruction algorithms. Diagnostic acceptability was significantly better in DLIR-M than the other reconstruction algorithms (p0.0001). The conspicuity of hepatic lesions was highest when using 40% ASiR-V and tended to lessen as the reconstruction strength level was getting higher in DLIR, especially in5 mm lesions; however, all hepatic lesions could be detected.DLIR improved the SNR, CNR, and image quality compared with 40% ASiR-V, while making it possible to decrease lesion conspicuity using higher reconstruction strength.

This study aims to compare the diagnostic values of mono-exponential, bi-exponential, and stretched exponential diffusion-weighted imaging (DWI) in differentiating hepatic hemangiomas and liver metastases.This prospective study was approved by our institutional review board, and written informed consent was obtained from all patients. In this study, 244 patients with known or suspected liver disease underwent magnetic resonance imaging. Among them, 37 patients who had focal hepatic lesions with a maximum diameter of ≥10 mm were evaluated. Using home-built software, two radiologists measured the DWI parameters of hepatic lesions for the three models: the apparent diffusion coefficient (ADC) from a mono-exponential model; the true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f) from a bi-exponential model; and the distributed diffusion coefficient (DDC) and water molecular diffusion heterogeneity index (α) from a stretched exponential model. The parameters were compared between hepatic hemangiomas and liver metastases.In total, 64 focal hepatic lesions were evaluated, of which 22 were identified to be hepatic hemangiomas and 42 were liver metastases. ADC, D, f, and DDC values were significantly lower in liver metastases than in hepatic hemangiomas (P 0.0001, 0.0001, 0.015, and 0.0001, respectively); whereas, the α value was significantly higher in liver metastases than in hepatic hemangiomas (P = 0.028). The areas under the ROC curve (AUCs) for differentiating hepatic hemangiomas and liver metastases in ADC, D, D*, f, DDC, and α were 0.940, 0.908, 0.608, 0.686, 0.952, and 0.667, respectively. The AUC values of ADC and DDC were significantly greater than those of D* (P 0.0001), f (P = 0.0001), and α values (P = 0.0001).ADC and DDC values from the mono-exponential and stretched exponential models could be considered as quantitative imaging biomarkers for differentiating hepatic hemangiomas and liver metastases.

To assess the efficacy of diffusion-weighted (DW) MR imaging for differentiating between Warthin’s tumor and oncocytoma of the parotid gland. Forty-five histopathologically confirmed parotid gland tumors (41 Warthin’s tumors and 4 oncocytomas) were examined by MR imaging including DW imaging. 18F-fluorodeoxyglucose PET/CT was also performed in 9 Warthin’s tumors and 3 oncocytomas. We retrospectively reviewed the images and compared the MR signal intensities, apparent diffusion coefficients (ADCs), and maximum standardized uptake values (SUVmax) of the solid components between the two pathologies. The signal intensity ratios (SIRs) on both T2-weighted images (0.92 ± 0.18 vs 0.65 ± 0.13, p

Objective:This study aimed to assess the imaging features and natural course of clavicle fracture following neck dissection (ND).Methods and materials:Eight patients with clavicle fracture following ND were included. Because bilateral clavicle fractures occurred in one patient, a total of nine clavicle fractures following ND were assessed using CT images. Pathological fracture due to bone metastasis or local recurrence was carefully ruled out.Results:The time interval from ND to clavicle fracture ranged from 2 to 8 months (median, 4 months). On CT images, all the nine fractures occurred in the proximal clavicles and displayed increased bone marrow density with extraosseous soft-tissue mass formation. Osteolysis of the clavicle was not observed. Intra articular fractures were observed in three (33%), displaced fractures in two (22%), and free bone fragments in three (33%) cases. Further follow-up using CT showed that six (67%) fractures resulted in pseudoarthrosis. For the remaining three (33%) fractures with bone union during follow-up, the time interval between clavicle fracture and bone union ranged from 4 to 16 months (median, 6 months).Conclusion:Proximal clavicle fractures, which are rarely observed following ND, always display extraosseous soft-tissue mass formation without osteolysis. They frequently result in pseudoarthrosis; however, occasionally, they also result in bone union within 24 weeks.Advances in knowledge:The location of proximal clavicle, the lack of osteolysis, and the presence of free bone fragments may be the key to diagnosis of clavicle fracture following ND.

Velocity and angular distributions of photofragment CO2+ ions produced from mass-selected (CO2)2+ at 532 nm excitation were observed in an ion imaging experiment. The velocity distribution was assigned to two components, fast and slow velocity components, which was consistent with the previous study by Bowers et al. The anisotropy parameters of the angular distributions for the fast and slow velocity components were experimentally determined to be βfast = 1.52 ± 0.14 and βslow = 0.46 ± 0.10, respectively. In the theoretical approach, potential energy surfaces (PESs) of (CO2)2+ were calculated along two coordinates, the intermolecular distance and mutual orientations of the CO2 monomers. In addition, molecular dynamics simulations were performed. The visible transition of the most stable staggered structure of (CO2)2+ was attributed to C[combining tilde]2Ag ← X[combining tilde]2Bu by an excited state calculation. On the PES of the C[combining tilde] state, a potential well was found in which the two CO2 monomers lay side by side to each other, in addition to a repulsive slope along the intermolecular distance. The results of the simulations confirmed that the fragment CO2+ ions with fast velocity and large anisotropy originated from the rapid dissociation of (CO2)2+ on the repulsive slope. Meanwhile, the fragment CO2+ ions with slow velocity and small anisotropy were expected to emerge from statistical dissociation after large amplitude libration of CO2 molecules which was caused by the potential well in the excited state PES.

Purpose To determine the optimal window settings for monochromatic images with various energy levels in single-source dual-energy computed tomography (DECT) of the abdomen. Materials and methods Two hundred consecutive patients underwent contrast-enhanced DECT to screen tumor metastases and/or recurrences after surgery for malignant tumors. Two independent radiologists reviewed eight energy levels (40, 45, 50, 55, 60, 65, 70, and 75 kilo-electron volts [keV]) of the portal venous phase monochromatic images. For each keV image, the radiologists adjusted the window level (WL) and width (WW) using settings of 40 HU of WL and 350 HU of WW on 65 keV images as a reference and recorded these values. After removing the top and bottom 5% of the data, the optimal WL and WW in each energy levels were obtained by rounding the median values. In 7 of 200 patients with a total of 23 liver metastases, the tumor-to-liver contrast-to-noise ratio (CNR) was calculated and compared among the energy levels. Results The optimal WLs and WWs at each energy level were as follows: 40 keV, 140 and 680 HU; 45 keV, 110 and 570 HU; 50 keV, 90 and 490 HU; 55 keV, 70 and 440 HU; 60 keV, 60 and 390 HU; 65 keV, 40 and 350 HU; 70 keV, 30 and 320 HU; and 75 keV, and 20 and 300 HU. The best CNR was obtained using 65 keV images (P Conclusion We clarified the optimal WL and WW available for the preset window settings in abdominal DECT.

An ion imaging apparatus with a double linear reflectron mass spectrometer has been developed, in order to measure velocity and angular distributions of mass-analyzed fragment ions produced by photodissociation of mass-selected gas phase complex ions. The 1st and the 2nd linear reflectrons were placed facing each other and controlled by high-voltage pulses in order to perform the mass-separation of precursor ions in the 1st reflectron and to observe the focused image of the photofragment ions in the 2nd reflectron. For this purpose, metal meshes were attached on all electrodes in the 1st reflectron, whereas the mesh was attached only on the last electrode in the 2nd reflectron. The performance of this apparatus was evaluated using imaging measurement of Ca+ photofragment ions from photodissociation reaction of Ca+Ar complex ions at 355 nm photoexcitation. The focused ion images were obtained experimentally with the double linear reflectron at the voltages of the reflection electrodes close to the predictions by ion trajectory simulations. The velocity and angular distributions of the produced Ca+ ([Ar] 4p1, 2P3/2) ion were analyzed from the observed images. The binding energy D0 of Ca+Ar in the ground state deduced in the present measurement was consistent with those determined theoretically and by spectroscopic measurements. The anisotropy parameter β of the transition was evaluated for the first time by this instrument.