Possible usefulness of fluorodeoxyglucose positron emission tomography in diagnosing polyarteritis nodosa: A case report and literature review.

Polyarteritis nodosa (PAN) is a systemic rheumatic disease that affects medium-sized arteries. PAN is typically not associated with anti-neutrophil cytoplasmic antibodies and has no serological surrogate markers. Therefore, its diagnosis requires pathological findings. However, the positive rate of biopsy in diagnosing PAN is not high, and the biopsy area is often limited. Several investigators have reported the usefulness of imaging findings in diagnosing PAN, independent of pathological findings. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET)/CT has recently been approved for the diagnosis of large-vessel vasculitis in Japan. Several studies have also demonstrated the usefulness of FDG-PET/CT in diagnosing medium-vessel vasculitis. However, no studies have evaluated the usefulness of FDG-PET/CT for diagnosing PAN compared to other modalities, and it is not clear whether FDG-PET/CT is superior to other modalities for diagnosing PAN. Herein, we report a case of PAN and compare the usefulness of FDG-PET/CT with other modalities in diagnosing PAN.

Localized nodular pulmonary amyloidosis mimicking primary lung cancer associated with cystic airspaces: A case report.

Localized nodular pulmonary amyloidosis can form pulmonary nodules associated with cystic air spaces, but due to its rarity, it cannot be included in the differential diagnosis without appropriate knowledge. Among the differential diagnoses of nodules with cysts in the lungs is primary lung cancer, however, diagnosis based solely on imaging findings is challenging. A 59-year-old Japanese female was referred to our hospital for an abnormality noted on the chest radiograph of an annual health check. She had no history of smoking or medical issues. Chest computed tomography revealed a 1.2 cm pulmonary nodule with surrounding multilocular cystic air spaces in the superior lingular segment. We suspected it was a nodule of primary lung cancer arising in the pulmonary cyst and performed video-assisted thoracic surgery. As the intraoperative frozen examination after a wedge resection revealed fibrotic tissue without malignancy, we did not do any further resection. The histopathological examination of the permanent section revealed unstructured eosinophilic deposits positive for direct fast scarlet staining, which were consistent with amyloidosis. The surrounding pulmonary cysts contained the check valve made by amyloid deposition. Localized nodular pulmonary amyloidosis can give rise to pulmonary cysts and mimic primary lung cancer associated with cystic air spaces. It should be raised as a potential differential diagnosis for pulmonary nodules with cystic air space formation, particularly in patients without a smoking history.

Time resolved DCE-MRI of the kidneys: Evaluation of the renal vasculatures and tumors using F-DISCO with and without compressed sensing in normal and wide-bore 3T systems.

Dynamic contrast-enhanced MR imaging (DCE-MRI) has been widely used for the evaluation of renal arteries. This method is also useful for tumor and renal parenchyma characterization. The very fast MRI may provide stable and precise information regarding vasculature and soft tissues. The purpose of this study was to evaluate the ability of DCE-MRI to assess renal vasculatures and tumor perfusions using Differential subsampling with Cartesian ordering with spectrally selected inversion recovery with adiabatic pulses (F-DISCO) with and without compressed sensing (CS) in normal and wide-bore 3T systems. Fifty-one patients who underwent DCE-MRI using F-DISCO with or without CS for evaluation of renal or adrenal regions were included. Image quality, artifacts, fat saturation, and selective visual recognition of renal vasculatures were assessed by using a 5-point scale. Tumor recognition was verified by using a 5-point scale of confidence level. Signal intensities of each structure were also measured. In all cases, the temporal resolution of each phase for DCE-MRI was 1.9 to 2.0 seconds. Image quality, artifacts, fat saturation, and selective visual recognition of vasculatures were all acceptable (mean score 4.2-4.9). The selective visualization of renal arteries and veins was successfully accomplished (mean score 4.0-4.9). Contrast media perfusion for renal vasculature, renal parenchyma, and tumors was also recognized. DCE-MRI for the evaluation of renal vasculatures and tumors using F-DISCO with or without CS can be performed with high temporal and spatial resolutions in normal and wide-bore 3T systems. This information can be obtained in a stable fashion throughout the dynamic contrast study. CS can additionally provide benefits that the total imaging time may be shorter than without CS.

Temporal subtraction of low-dose and relatively thick-slice CT images with large deformation diffeomorphic metric mapping and adaptive voxel matching for detection of bone metastases: A STARD-compliant article.

To evaluate the improvement of radiologist performance in detecting bone metastases at follow up low-dose computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm.Twelve patients with bone metastases (males, 5; females, 7; mean age, 64.8 ±â€Š7.6 years; range 51-81 years) and 12 control patients without bone metastases (males, 5; females, 7; mean age, 64.8 ±â€Š7.6 years; 51-81 years) were included, who underwent initial and follow-up CT examinations between December 2005 and July 2016. Initial CT images were registered to follow-up CT images by the algorithm, and TS images were created. Three radiologists independently assessed the bone metastases with and without the TS images. The reader averaged jackknife alternative free-response receiver operating characteristics figure of merit was used to compare the diagnostic accuracy.The reader-averaged values of the jackknife alternative free-response receiver operating characteristics figures of merit (θ) significantly improved from 0.687 for the readout without TS and 0.803 for the readout with TS (P value = .031. F statistic = 5.24). The changes in the absolute value of CT attenuations in true-positive lesions were significantly larger than those in false-negative lesions (P < .001). Using TS, segment-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the readout with TS were 66.7%, 98.9%, 94.4%, 90.9%, and 94.8%, respectively.The TS images can significantly improve the radiologist's performance in the detection of bone metastases on low-dose and relatively thick-slice CT.

T2-weighted MRI of rectosigmoid carcinoma: comparison of respiratory-triggered fast spin-echo, breathhold fast-recovery fast spin-echo, and breathhold single-shot fast spin-echo sequences.

PURPOSE: To compare the abilities of T2-weighted (T2W) imaging using respiratory-triggered fast spin-echo (RT-FSE), breathhold fast-recovery FSE (BH-FRFSE), and BH single-shot FSE (BH-SSFSE) sequences without an endorectal coil to detect rectosigmoid carcinomas. MATERIALS AND METHODS: Forty patients (stage: pT0, 1; pTis-2, 15; pT3-4, 24) were included in the study. All examinations were performed on a 1.5T magnet with a phased-array coil and the patients were studied in the prone position with per-anal air injection. Qualitative and quantitative evaluations were performed. RESULTS: Motion artifact was the most prominent with the RT-FSE sequence, and the least prominent with the BH-SSFSE sequence. Scores for depiction of the rectal wall layer, tumor recognition, and overall image quality were the highest with the BH-FRFSE sequence. On the basis of a receiver operating characteristic (ROC) analysis, the detection rate of tumor invasion through the rectal wall was higher with the BH-FRFSE sequence (Az = 0.9077) than with the RT-FSE (Az = 0.7762, p < 0.05) or BH-SSFSE (Az = 0.8602) sequence. Tumor-to-fat contrast was highest with the BH-FRFSE sequence (P < 0.017). CONCLUSION: The BH-FRFSE sequence may be the first choice for rectosigmoid T2W imaging in the prone position with per-anal air injection for patients who can hold their breath stably.

Magnetic resonance cholangiopancreatography: comparison of respiratory-triggered three-dimensional fast-recovery fast spin-echo with parallel imaging technique and breath-hold half-Fourier two-dimensional single-shot fast spin-echo technique.

PURPOSE: The aim of this study was to compare magnetic resonance cholangiopancreatography (MRCP) using respiratory-triggered (resp) three-dimensional Fourier transformation (3D) fast-recovery fast spin echo (FR-FSE) sequence with array spatial sensitivity technique (ASSET) for visualization of the pancreatobiliary system with breath-hold single thick-section and multiple thin-section MRCP using 2D single shot FSE (SSFSE) sequences. MATERIALS AND METHODS: Forty patients underwent MRCP for evaluation of pancreatobiliary abnormalities in a 1.5-T magnet. Imaging time for resp 3D FR-FSE was recorded. The ghosting and blurring artifacts, overall image quality, and delineation of the pancreatobiliary ducts were evaluated using a five-point scale. RESULTS: On multisection 2D SSFSE source images, there were the least ghosting artifacts (4.9 +/- 0.3, P < 0.05). Ghosting (3.4 +/- 0.6, P < 0.05) and blurring (4.4 +/- 0.8; P < 0.05) artifacts were the most prominent on resp 3D FR-FSE. 3D FR-FSE MRCP provided the highest rating of overall image quality (4.3 +/- 0.8, P < 0.05) and delineation of third- and second-order branches of the hepatic ducts (2.9 +/- 1.6 for third-order branches and 3.9 +/- 1.3 for second-order branches, P < 0.05). Extrahepatic bile ducts, including upper and middle portions and cystic and pancreatic ducts, were also better seen with resp 3D FR-FSE MRCP than others. CONCLUSION: MRCP with resp 3D FR-FSE using ASSET can be routinely used for acquiring information from the pancreatobiliary system.

Intravenous injection of high and medium concentrations of computed tomography contrast media and related heat sensation, local pain, and adverse reactions.

OBJECTIVES: To evaluate the incidence of acute adverse reactions and degrees of heat sensation and local pain after intravenous injection of high and medium concentrations of iodinated contrast medium for computed tomography (CT). METHODS: A prospective study was performed involving 729 patients who underwent contrast CT scans. High-concentration (370 mgI/mL) and medium-concentration (300 mgI/mL) iodinated contrast medium was assigned to 342 patients (group H, aged 20-90 years, mean = 59.8 years) and to 387 patients (group M, aged 20-95 years, mean = 61.7 years), respectively. An injection rate of contrast medium (1, 2, or 4 mL/s) at a base volume of 2 mL/kg of body weight was selected according to the protocols for the evaluated diseases and regions. Each patient was assessed for heat sensation and local pain at the injection site using a visual analog scale (ranging from none for 0 to severe for 10). Acute adverse reactions were recorded when they occurred. RESULTS: There were no significant differences in patient background factors, including age, sex, history of prior adverse reactions, and allergies, between the 2 groups. The score for heat sensation was significantly higher in group H than in group M (4.46 +/- 2.44 vs. 3.44 +/- 2.45; P < 0.0001 for heat sensation). The data did not show a higher incidence of adverse reactions in group H than in group M (5 [1.46%] of 342 patients vs. 2 [0.52%] of 387 patients; P = 0.26) or a higher score for local pain in group H than in group M (0.98 +/- 1.70 vs. 0.88 +/- 1.49; P = 0.66), respectively. CONCLUSIONS: High and medium concentrations of iodinated contrast medium can be used for CT study with comparable safety profiles even though heat sensation produced by the high-concentration CM is greater than that produced by the medium-concentration CM.

MR imaging of primary malignant lymphoma of the pancreas.

Pancreatic lymphoma is rare and is usually found as a large pancreatic mass. We report the case of a small 2-cm pancreatic lymphoma in a 54-year-old woman that had its histological origin in the pancreatic parenchyma. The mass showed homogeneously high signal-intensity on T2-weighted images and low signal-intensity on T1-weighted images. The infiltrative nature and hypovascularity in early-phase dynamic contrast study without encasement of arteries and veins were well demonstrated by MR imaging and were consistent with malignant lymphoma.

Exophytic giant cavernous hemangioma of the liver with growing tendency.

Hepatic hemangioma is a common benign tumor, but its exophytic and expansile forms may be atypical. We report a case of exophytic hemangioma of the liver with a growing tendency, demonstrated using magnetic resonance imaging (MRI) and computed tomography (CT) combined with angiography.

Pseudolesions related to uterine contraction: characterization with multiphase-multisection T2-weighted MR imaging.

PURPOSE: To evaluate whether multiphase-multisection T2-weighted magnetic resonance (MR) images help exclude pseudolesions mimicking leiomyoma and adenomyosis on static T2-weighted fast spin-echo (FSE) MR images and to characterize temporal changes in uterine signal intensity related to uterine contraction. MATERIALS AND METHODS: T2-weighted FSE and multiphase-multisection single-shot FSE (SSFSE) MR imaging were performed in 43 patients who underwent hysterectomy. Each imaging set was evaluated separately by two independent readers, and receiver operating characteristic analysis was performed. In the 43 patients and in 49 other patients suspected of having pelvic abnormality, a combination of signal intensity changes on FSE and SSFSE MR images was classified into five patterns, and temporal low-signal-intensity changes on SSFSE MR images were characterized. RESULTS: For detection of leiomyoma on FSE and SSFSE MR images, the respective values of the area under the receiver operating characteristic curve were 0.98 and 0.97 for reader 1 and 0.96 and 0.96 for reader 2; for detection of adenomyosis on FSE and SSFSE MR images, the respective values were 0.82 and 0.84 for reader 1 and 0.80 and 0.89 for reader 2 (P >.05). SSFSE MR images helped exclude pseudolesions in 1%-3% cases of leiomyoma and in 3%-4% cases of adenomyosis. Temporal signal intensity changes were observed in 53% of 368 segments. The most frequent shape of temporal low signal intensity was diffuse followed by ill-defined focal type. Characteristic shape of temporal low signal intensities was band- or sticklike, which was observed in as many as 19% of 368 segments. CONCLUSION: Multiphase-multisection T2-weighted SSFSE MR images do not improve accuracy in detection of leiomyoma and adenomyosis compared with FSE MR images; however, they helped characterize features of temporal low signal intensities in the uterus, which are related to uterine contractions.

Diffusion-weighted echo planar imaging of ovarian tumors: is it useful to measure apparent diffusion coefficients?

PURPOSE: Our goal was to test the hypothesis, as previously reported in other studies, that apparent diffusion coefficients (ADCs) provide specific information to diagnose ovarian tumors, especially to discriminate between benign and malignant lesions. METHOD: T1-and T2-weighted spin echo imaging and diffusion-weighted echo planar imaging were performed in 31 women with 61 cystic components of ovarian tumors. RESULTS: The lesions that showed typical watery intensity, hypointensity in T1-weighted imaging, and hyperintensity in T2-weighted imaging had similar ADCs, ranging from 1.54 to 1.84 x 10(-3) mm2 /s. The lesions that showed signal intensity different from typical watery intensity in conventional MRI tended to have low ADCs. In endometrial cysts, the mean ADC of the subgroup that showed typical watery intensity was higher than that of other subgroups. CONCLUSION: With conventional MRI, a tendency of ADCs could be predicted. ADCs may not provide additional information, especially to discriminate benign from malignant lesions.