Assessment for Carotid Atherosclerotic Plaque Using Vessel Wall Magnetic Resonance Imaging: A Multireader ROC Study to Determine Optimal Sequence for Detecting Vessel Wall Calcification.

INTRODUCTION: We aimed to compare conventional vessel wall MR imaging techniques and quantitative susceptibility mapping (QSM) to determine the optimal sequence for detecting carotid artery calcification. METHODS: Twenty-two patients who underwent carotid vessel wall MR imaging and neck CT were enrolled. Four slices of 6-mm sections from the bilateral internal carotid bifurcation were subdivided into 4 segments according to clock position (0-3, 3-6, 6-9, and 9-12) and assessed for calcification. Two blinded radiologists independently reviewed a total of 704 segments and scored the likelihood of calcification using a 5-point scale on spin-echo imaging, FLASH, and QSM. The observer performance for detecting calcification was evaluated by a multireader, multiple-case receiver operating characteristic study. Weighted κ statistics were calculated to assess interobserver agreement. RESULTS: QSM had a mean area under the receiver operating characteristic curve of 0.85, which was significantly higher than that of any other sequence (p < 0.01) and showed substantial interreader agreement (κ = 0.68). A segment with a score of 3-5 was defined as positive, and a segment with a score of 1-2 was defined as negative; the sensitivity and specificity of QSM were 0.75 and 0.87, respectively. CONCLUSION: QSM was the most reliable MR sequence for the detection of plaque calcification.

Significance of Low Signal in Intracranial Vertebral Artery Wall Observed on Susceptibility-Weighted Angiography.

PURPOSE: We aimed to investigate the clinical significance of the low signal in the intracranial vertebral artery wall observed on susceptibility-weighted angiography. MATERIALS AND METHODS: We retrospectively reviewed susceptibility-weighted angiographies from 200 consecutive patients with acute ischemic stroke in the posterior circulation territory. The presence of eccentric or concentric low signals in the vertebral artery wall was examined and evaluated. The etiology of the low signal was also investigated as much as possible by referring to computed tomography and T1-weighted imaging (T1WI). We also compared its frequency in each stroke subtype. RESULTS: A low signal was observed in 128/200 patients (64%). The low signals (58%) corresponded to vessel wall calcification in 74 of 128 patients and to vessel wall thickening showing intermediate to low (n = 8) or high (n = 16) signals on T1WI in 24 (19%) patients. The low signal did not have vessel wall thickening or calcification in 1 patient, and the cause of the low signal could not be verified in 29 patients. According to stroke subtypes, a low signal was observed in 14/14 (100%) vertebral artery dissections, all of which corresponded to intramural hematoma. A low signal was observed in 51/65 (78%) atherothromboses, which were significantly more frequent than cardioembolism (34/66; 52%) and small-artery disease (18/39; 46%) (p < 0.01). In atherothrombosis, calcification was the most common cause of low signal (n = 32; 63%). CONCLUSION: Low signals on susceptibility-weighted angiography were frequently observed in vertebral artery dissection and atherothrombosis, reflecting intramural hematoma in all of the former and predominantly calcification in the latter.

A case of Lemierre's syndrome with double vision as the first symptom.

Lemierre's syndrome is a serious disease that typically causes oropharyngeal infection with internal jugular vein thrombosis, followed by distant infection focus, such as septic pulmonary embolism. The main causative organisms are anaerobic bacteria in the oral cavity, namely Fusobacterium necrophorum. We encountered an extremely rare case of Lemierre's syndrome, where double vision was found to be the first symptom. The patient's blood culture results showed the presence of F. nucleatum, which spread from the sphenoid sinus to the skull base because of chronic sinusitis; the patient presented with longus colli abscess, clivus osteomyelitis, venous thrombosis, and hematogenous infection. Antibiotic treatment with sulbactam/ampicillin was continued for 14 weeks, and no recurrence has been observed so far. Lemierre's syndrome can be complicated with atypical symptoms such as double vision if the cranial nerves are involved. It might be important to consider this disease in the differential diagnosis in the presence of cranial nerve symptoms of unknown origin with fever or inflammatory findings.

Amide proton transfer MRI differentiates between progressive multifocal leukoencephalopathy and malignant brain tumors: a pilot study.

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nerve system caused by the John Cunningham virus. On MRI, PML may sometimes appear similar to primary central nervous system lymphoma (PCNSL) and glioblastoma multiforme (GBM). The purpose of this pilot study was to evaluate the potential of amide proton transfer (APT) imaging for differentiating PML from PCNSL and GBM. METHODS: Patients with PML (n = 4; two men; mean age 52.3 ± 6.1 years), PCNSL (n = 7; four women; mean age 74.4 ± 5.8 years), or GBM (n = 11; 6 men; mean age 65.0 ± 15.2 years) who underwent APT-CEST MRI between January 2021 and September 2022 were retrospectively evaluated. Magnetization transfer ratio asymmetry (MTRasym) values were measured on APT imaging using a region of interest within the lesion. Receiver operating characteristics curve analysis was used to determine diagnostic cutoffs for MTRasym. RESULTS: The mean MTRasym values were 0.005 ± 0.005 in the PML group, 0.025 ± 0.005 in the PCNSL group, and 0.025 ± 0.009 in the GBM group. There were significant differences in MTRasym between PML and PCNSL (P = 0.023), and between PML and GBM (P = 0.015). For differentiating PML from PCNSL, an MTRasym threshold of 0.0165 gave diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of 100% (all). For differentiating PML from GBM, an MTRasym threshold of 0.015 gave diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 90.9%, 80.0%, and 100%, respectively. CONCLUSION: MTRasym values obtained from APT imaging allowed patients with PML to be clearly discriminated from patients with PCNSL or GBM.

Quantitative Chemical Exchange Saturation Transfer Imaging of Amide Proton Transfer Differentiates between Cerebellopontine Angle Schwannoma and Meningioma: Preliminary Results.

Vestibular schwannomas are the most common tumor at the common cerebellopontine angle, followed by meningiomas. Differentiation of these tumors is critical because of the different surgical approaches required for treatment. Recent studies have demonstrated the utility of amide proton transfer (APT)-chemical exchange saturation transfer (CEST) imaging in evaluating malignant brain tumors. However, APT imaging has not been applied in benign tumors. Here, we explored the potential of APT in differentiating between schwannomas and meningiomas at the cerebellopontine angle. We retrospectively evaluated nine patients with schwannoma and nine patients with meningioma who underwent APT-CEST MRI from November 2020 to April 2022 pre-operation. All 18 tumors were histologically diagnosed. There was a significant difference in magnetization transfer ratio asymmetry (MTRasym) values (0.033 ± 0.012 vs. 0.021 ± 0.004; p = 0.007) between the schwannoma and meningioma groups. Receiver operative curve analysis showed that MTRasym values clearly differentiated between the schwannoma and meningioma groups. At an MTRasym value threshold of 0.024, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTRasym were 88.9%, 77.8%, 80.0%, and 87.5%, respectively. Our results demonstrated the ability of MTRasym values on APT-CEST imaging to discriminate patients with schwannomas from patients with meningiomas.

Comparison of the quantitative measurement of 18F-FDG PET/CT and histopathological findings in IgG4-related disease.

OBJECTIVES: To investigate the utility of 18F-FDG PET/CT in the diagnostic procedure of IgG4-related disease (IgG4-RD), we analysed the association between quantitative method of 18F-FDG PET/CT and histological findings. METHODS: Twenty-one patients with IgG4-RD in whom 18F-FDG PET/CT was performed at the time of diagnosis were enrolled. Tissue biopsy was performed at 24 sites in 21 patients. To perform quantitative analysis of 18F-FDG PET/CT imaging, the highest standardised uptake value (SUV) of the pixels (SUVmax) and the average SUV (SUVmean) within the biopsied lesion were measured. The SUVmean of the liver was also measured as a reference. RESULTS: The mean age at diagnosis was 64.6±11.9 years, and the median serum IgG4 level was 650 mg/dl. Histological findings were consistent with IgG4-RD (histopathology-positive) at 19 out of 24 sites. Although there was no significant difference in the values of SUVmax between histopathology-positive and histopathology-negative tissues, the values of SUVmean were significantly higher in the histopathology-positive tissue (4.98 and 3.54, respectively p<0.05). The values of SUVmean/liver were also higher in the histopathology-positive tissue (2.17 and 1.52, respectively p<0.05). To establish a cut-off value of SUVmean to determine which of multiple lesions should be biopsied, a ROC curve was constructed. ROC curve analysis indicated SUVmean=4.07 or SUVmean/liver=1.66 as a cut-off value. CONCLUSIONS: Our present study suggested that quantitative analysis of 18F-FDG-PET/CT imaging might be useful for selecting the biopsy site in IgG4-RD. The calculation of SUVmean, not of SUVmax, is important for evaluating IgG4-RD-related lesions in 18F-FDG PET/CT imaging.

Traumatic myositis ossificans: multifocal lesions suggesting malignancy on FDG-PET/CT-a case report.

Myositis ossificans (MO) is a benign soft-tissue lesion characterized by the heterotopic formation of the bone in skeletal muscles, usually due to trauma. MO is occasionally difficult to diagnose because of its clinical and radiological similarities with malignancy. We report a case of traumatic MO (TMO) in the masseter and brachial muscles of a 37-year-old man who presented with painless swelling in the left cheek and severe trismus. Due to the absence of a traumatic history at the first consultation and identification of a tumorous lesion in the left masseter muscle by magnetic resonance imaging (MRI), the lesion was suspected to be a malignant tumor. Subsequently, 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) showed multiple regions of high FDG uptake across the whole body, suggestive of multiple metastases or other systemic diseases. However, intramuscular calcifications were also observed in the left masseter and brachial muscles, overlapping the areas with high FDG uptake. Moreover, multiple fractures were seen in the rib and lumbar spine, also overlapping the areas with high FDG uptake. Based on these imaging findings, along with a history of jet-ski trauma, TMO was suspected. The left cheek mass was surgically excised and histologically diagnosed as TMO. In this case report, FDG-PET/CT could detect multiple TMOs across the whole body. To the best of our knowledge, cases of multiple TMOs located far apart in different muscles are rare, and this may be the first report.

[Ictal arterial spin labeling MRI findings in two cases of acute confusional migraine].

Arterial spin labeling (ASL) is a magnetic resonance imaging (MRI) technique that enables visualizing of cerebral blood flow without need of a contrast medium. In recent years, there have been reports from outside Japan related to ASL use in migraine attacks. We report two cases of acute confusional migraine (ACM) in children. At time of confusion, ASL imaging showed reduced blood flow: for the first patient, in both cerebral hemispheres from the occipital lobe through the parietal lobe to the temporal lobe; for the second patient, throughout the left cerebral hemisphere. T1-, T2-, diffusion-weighted images, and fluid attenuation inversion recovery (FLAIR) images indicated normal results. Subsequent ASL re-examinations for both cases showed recovery from reduced blood flow. In our view, ACM can be characterized by a reduction in blood flow not limited to the occipital lobe but across wide regions of the cerebral hemisphere. We consider ASL to be helpful in the difficult differentiation of ACM from other disturbances of consciousness, in addition to enabling repeated examinations without the risks associated with single-photon emission computed tomography (SPECT) concerning radiation exposure or with contrast MRI concerning contrast media use.

Optimizing cardiac amyloidosis assessment: utility of 1-h and 3-h 99mTc-PYP imaging.

BACKGROUND: Transthyretin amyloid cardiomyopathy (ATTR-CM), characterized by the extracellular deposition of an insoluble amyloid protein in the heart, is one of the main causes of heart failure in elderly patients. In this study, our primary objective was to explore the diverse applications and temporal significance of 1-h and 3-h imaging using 99mTc-PYP in the context of ATTR-CM. Additionally, we compared tracer kinetics in the heart and bone to comprehensively assess the diagnostic advantages and time-related considerations associated with these two incubation periods. METHODS: Twenty-seven patients at Nagasaki University Hospital who underwent 99mTc-PYP planar, and SPECT cardiac imaging were classified into two groups (ATTR-CM-positive and -negative groups) based on the American Heart Association statement. Cardiac retention was assessed with both a semiquantitative visual score and a quantitative analysis. To assess bone accumulation, a ROI with an equal volume was drawn on the sternum and calculated as the bone-to-contralateral ratio (B/CL). We also evaluated correlation between heart-to-contralateral lung (H/CL) ratio and left ventricular wall thickness. RESULTS: Among patients who underwent 99mTc-PYP imaging, the H/CL ratio was significantly higher at 1 h than at 3 h regardless of the group (from 2.20 ± 0.36 to 1.99 ± 0.35, p < 0.01 in the positive group and from 1.35 ± 0.12 to 1.19 ± 0.21, p = 0.01 in the negative group). The gap of H/CL between highest H/CL of negative case and lowest H/CL of positive case was narrower in 3 h. On the other hand, correlation between H/CL and left ventricular posterior wall thickness tends to be clearer in 3 h (p = 0.12, r = 0.30 for 1 h, p = 0.04, r = 0.39 at 3 h). CONCLUSION: Our study suggests that both 1-h and 3-h incubation times for 99mTc-PYP imaging have different benefits for ATTR cardiac amyloidosis. A one-hour incubation may be preferable for differential diagnostic purposes, while a three-hour incubation may provide greater utility in evaluating disease severity.

Cardiac Sarcoidosis which Occurred four Years after Successful Treatment of Cutaneous Sarcoidosis with Minocycline.

A 67-year-old woman was admitted to our hospital because of a complete right bundle branch block. She had been treated with minocycline for skin sarcoidosis and her symptoms had ameliorated four years previously. Gallium scintigraphy revealed an abnormal uptake in the heart but not in the skin or lungs. She was diagnosed with cardiac sarcoidosis, although an endomyocardial biopsy could not detect any sarcoid lesions. Immunohistochemical staining for Cutibacterium acnes was positive for granulomas of the skin lesions which had been previously biopsied. One year after starting the administration of steroids, her condition improved.

Assessment of Interobserver Agreement in the Interpretation of 99mTc-PYP SPECT Imaging of Cardiac Amyloidosis.

Background: Technetium-99m pyrophosphate single photon emission computed tomography (99mTc-PYP SPECT) imaging is widely used to diagnose cardiac amyloidosis, a disease characterized by amyloid protein deposits in the myocardium. The effects of viewing perspectives on interobserver agreement in the interpretation of 99mTc-PYP SPECT images for the diagnosis of cardiac amyloidosis remain unclear. Methods: A retrospective analysis of 32 consecutive patients who underwent 99mTc-PYP imaging for the diagnosis of cardiac amyloidosis at Nagasaki University Hospital between October 2017 and February 2020 was performed. Four evaluators independently reviewed coronal, sagittal, and transaxial images and then all images together and made a categorical diagnosis based on predefined criteria. Interobserver agreement was analyzed using Cohen's Kappa analysis. Results: Kappa coefficient values in the four-grade grading system (grades 0-3) ranged between 0.31 and 0.95, while those in the binary grading system (positive/negative) ranged between 0.88 and 1. The sagittal view showed the highest value in the four-grade grading system (0.95) and the lowest in the binary grading system (0.88). The transaxial view was more likely to show a consistently high kappa value in both the four-grade and binary grading systems. The use of the multiplanar view reduced the number of subjects classified as grade 1. Conclusion: Our study demonstrates that the transaxial view provides the most consistent interpretation of 99mTc-PYP SPECT images for the diagnosis of cardiac amyloidosis. The use of the multiplanar view may also reduce equivocal interpretations, which are graded as grade 1. Further studies with larger sample sizes and a quantitative analysis are needed to confirm the present results.

Amide Proton Transfer-Chemical Exchange Saturation Transfer Imaging of Intracranial Brain Tumors and Tumor-like Lesions: Our Experience and a Review.

Chemical exchange saturation transfer (CEST) is a molecular magnetic resonance imaging (MRI) method that can generate image contrast based on the proton exchange between labeled protons in solutes and free, bulk water protons. Amide proton transfer (APT) imaging is the most frequently reported amide-proton-based CEST technique. It generates image contrast by reflecting the associations of mobile proteins and peptides resonating at 3.5 ppm downfield from water. Although the origin of the APT signal intensity in tumors is unclear, previous studies have suggested that the APT signal intensity is increased in brain tumors due to the increased mobile protein concentrations in malignant cells in association with an increased cellularity. High-grade tumors, which demonstrate a higher proliferation than low-grade tumors, have higher densities and numbers of cells (and higher concentrations of intracellular proteins and peptides) than low-grade tumors. APT-CEST imaging studies suggest that the APT-CEST signal intensity can be used to help differentiate between benign and malignant tumors and high-grade gliomas and low-grade gliomas as well as estimate the nature of lesions. In this review, we summarize the current applications and findings of the APT-CEST imaging of various brain tumors and tumor-like lesions. We report that APT-CEST imaging can provide additional information on intracranial brain tumors and tumor-like lesions compared to the information provided by conventional MRI methods, and that it can help indicate the nature of lesions, differentiate between benign and malignant lesions, and determine therapeutic effects. Future research could initiate or improve the lesion-specific clinical applicability of APT-CEST imaging for meningioma embolization, lipoma, leukoencephalopathy, tuberous sclerosis complex, progressive multifocal leukoencephalopathy, and hippocampal sclerosis.

Usefulness of arterial spin labeling imaging, which contributed to the early detection of cerebellitis complicated by clinically mild encephalitis/encephalopathy with a reversible splenial lesion: Lessons from three cases.

BACKGROUND: Cerebellitis is a rare complication of clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS); however, MERS with cerebellitis is associated with a higher risk of neurological sequelae in comparison to MERS alone. Although the disease is difficult to diagnose by conventional MRI in the early disease phase, arterial spin labeling (ASL), a noninvasive MRI perfusion technique using magnetically-labeled arterial blood water protons, is considered promising. CASE REPORT: We experienced three cases of MERS with cerebellitis. Diffusion-weighted imaging showed a high-intensity lesion at the splenium of the corpus callosum. ASL showed increased blood flow in the cerebellum in all three cases, despite cerebellar symptoms being inapparent or difficult to notice in the early phase of disease in all cases. Patients received methylprednisolone pulse therapy and intravenous immunoglobulin from the early phase of the disease and recovered without neurological sequelae. DISCUSSION: ASL magnetic response imaging simultaneously showed an area of hyperperfusion in the cerebellum. At the same time, the apparent diffusion coefficient of the splenial lesion was decreased in all three cases. The successful diagnosis of cerebellitis in the acute phase led to early therapeutic intervention, which may be important for this condition. We report the usefulness of ASL and review the relevant literature on MERS with cerebellitis.

Neuroimaging findings of inborn errors of metabolism: urea cycle disorders, aminoacidopathies, and organic acidopathies.

Although there are many types of inborn errors of metabolism (IEMs) affecting the central nervous system, also referred to as neurometabolic disorders, individual cases are rare, and their diagnosis is often challenging. However, early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurological impairment or death. The clinical course of IEMs is very diverse, with some diseases progressing to acute encephalopathy following infection or fasting while others lead to subacute or slowly progressive encephalopathy. The diagnosis of IEMs relies on biochemical and genetic tests, but neuroimaging studies also provide important clues to the correct diagnosis and enable the conditions to be distinguished from other, more common causes of encephalopathy, such as hypoxia-ischemia. Proton magnetic resonance spectroscopy (1H-MRS) is a powerful, non-invasive method of assessing neurological abnormalities at the microscopic level and can measure in vivo brain metabolites. The present review discusses neuroimaging findings, including those of 1H-MRS, of IEMs focusing on intoxication disorders such as urea cycle disorders, aminoacidopathies, and organic acidopathies, which can result in acute life-threatening metabolic decompensation or crisis.

Impact of width of susceptibility vessel sign on recanalization following endovascular therapy.

BACKGROUND AND PURPOSE: We aimed to investigate the relationship between arterial recanalization following endovascular therapy and the susceptibility vessel sign (SVS) length and width on susceptibility-weighted imaging. METHODS: We retrospectively evaluated consecutive patients with anterior circulation ischemic stroke who underwent magnetic resonance imaging preceded endovascular therapy, and measured the SVS length and width. Successful recanalization was defined as expanded thrombolysis in cerebral infarction grade of 2b to 3. Logistic regression analysis was executed to determine the independent predictors of successful recanalization and first-pass reperfusion (FPR) after endovascular therapy. RESULTS: Among 100 patients, successful recanalization and FPR were observed in 77 and 34 patients, respectively. The median SVS length and width were 10.3 mm (interquartile range, 6.8-14.1 mm) and 4.2 mm (interquartile range, 3.1-5.2 mm), respectively. In multivariate logistic regression analysis, SVS width was associated with successful recanalization (odds ratio, 1.88; 95% confidence interval, 1.14-3.07; p = 0.005) and FPR (odds ratio, 1.38; 95% confidence interval, 1.01-1.89; p = 0.039). The optimal cutoff value for the SVS width to predict successful recanalization and FPR were 4.2 mm and 4.0 mm, respectively. CONCLUSIONS: Larger SVS width may predict successful recanalization and FPR following endovascular therapy.

Ivy signs on FLAIR images before and after STA-MCA anastomosis in patients with Moyamoya disease.

BACKGROUND: Leptomeningeal high signal intensity (ivy sign) on fluid-attenuated inversion-recovery (FLAIR) MR imaging is one of the features of Moyamoya disease. However, the correlation between ivy sign and cerebral perfusion status has not been fully evaluated. PURPOSE: To characterize ivy sign on FLAIR images in Moyamoya disease and compare this finding with hemodynamic alterations on perfusion single-photon emission CT (SPECT) obtained before and after bypass surgery. MATERIAL AND METHODS: Sixteen patients with angiographically confirmed Moyamoya disease who underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis were included in the study. The presence of ivy sign on FLAIR images was classified as 'negative', 'minimal' and 'positive'. We evaluated the relationship between ivy sign and findings of SPECT, including cerebral vascular reserve (CVR) before and after surgery. RESULTS: Minimal or positive ivy sign was seen in 13 (81%) of 16 patients, and 21 (66%) of 32 hemispheres. CVR in the areas with positive or minimal ivy sign was lower than that in the areas with negative ivy sign. After STA-MCA anastomosis, ivy sign disappeared or decreased in all 21 hemispheres demonstrating ivy sign. SPECT demonstrated apparent hemodynamic improvement in areas demonstrating disappearance or decrease of ivy sign. CONCLUSION: Ivy sign on FLAIR image is seen in areas with decreased cerebral perfusion. The sign is useful for non-invasive assessment of cerebral hemodynamic status before and after surgery.

FDG-PET vs. chemical shift MR imaging in differentiating intertrabecular metastasis from hematopoietic bone marrow hyperplasia.

PURPOSE: To evaluate the utility of SUVmax on FDG-PET and chemical shift imaging (CSI) on MRI in the differentiation of intertrabecular metastasis (ITM) from hematopoietic bone marrow hyperplasia (HBMH). PATIENTS AND METHODS: We retrospectively evaluated 54 indeterminate focal bone marrow lesions in 44 patients detected on FDG-PET. The lesions were assigned to the metastasis group (M group, 29 lesions of 24 patients) and the non-metastasis group (non-M group, 25 lesions of 20 patients) based on the follow-up or the histopathological studies. The lesions were assessed with the maximum standardized uptake value (SUVmax) on FDG-PET CT images and signal change ratio (SCR) on CSI. RESULTS: The median SUVmax were 5.62 and 2.91; the median SCR were - 0.08 and - 34.8 in M and non-M groups respectively, with significant difference (p < 0.001). With ROC curve analysis, the optimal cutoff value of SUVmax was 4.48 with a sensitivity of 72.4%, a specificity of 100%, and AUC of 0.905. The cutoff value of SCR was - 6.15 with a sensitivity of 82.8%, a specificity of 80%, and AUC of 0.818. CONCLUSION: FDG-PET and CSI on MRI are useful in distinguishing ITM from HBMH. Though their sensitivities are similar, the specificity of FDG-PET was higher than that of MRI.

Quantitative Susceptibility Mapping for Carotid Atherosclerotic Plaques: A Pilot Study.

PURPOSE: Identifying plaque components such as intraplaque hemorrhage, lipid rich necrosis, and calcification is important to evaluate vulnerability of carotid atherosclerotic plaque; however, conventional vessel wall MR imaging may fail to discriminate plaque components. We aimed to evaluate the components of plaques using quantitative susceptibility mapping (QSM), a newly developed post-processing technique to provide voxel-based quantitative susceptibilities. METHODS: Seven patients scheduled for carotid endarterectomy were enrolled. Magnitude and phase images of five-echo 3D fast low angle shot (FLASH) were obtained using a 3T MRI, and QSM was calculated from the phase images. Conventional carotid vessel wall images (black-blood T1-weighted images [T1WI], T2-weighted images [T2WI], proton-density weighted images [PDWI], and time-of-flight images [TOF]) were also obtained. Pathological findings including intraplaque hemorrhage, calcification, and lipid rich necrosis at the thickest plaque section were correlated with relative susceptibility values with respect to the sternocleidomastoid muscle on QSM. On conventional vessel wall images, the contrast-noise ratio (CNR) between the three components and sternocleidomastoid muscle was measured respectively. Wilcoxon signed-rank test analyses were performed to assess the relative susceptibility values and CNR. RESULTS: Pathologically, lipid rich necrosis was proved in all of seven cases, and intraplaque hemorrhage in five of seven cases. Mean relative susceptibility value of hemorrhage was higher than lipid rich necrosis unexceptionally (P = 0.0313). There were no significant differences between CNR of hemorrhage and lipid rich necrosis on all sequences. In all six cases with plaque calcification, susceptibility value of calcification was significantly lower than lipid rich necrosis unexceptionally (P = 0.0156). There were significant differences between CNRs of lipid rich necrosis and calcification on T1WI, PDWI, TOF (P < 0.05). CONCLUSION: QSM of carotid plaque would provide a novel quantitative MRI contrast that enables reliable differentiation among intraplaque hemorrhage, lipid rich necrosis, and calcification, and be useful to identify vulnerable plaques.

Radiation Monitoring of an Isolation Room for 131I Therapy After the Patients Were Released.

PURPOSE: This study was performed to obtain a better understanding of the radiation environment in an I isolation room after the release of patients with metastasis from thyroid cancer that were treated with I doses ranging from 3.7 GBq (100 mCi) to 5.5 GBq (150 mCi) because there have not been any previous studies regarding the ambient radiation levels encountered in I isolation rooms after patients are released. METHODS: Ambient radiation levels and total and removable surface contamination levels were monitored for 3 weeks after each patient's release (and before the entry of the next patient). An area located 0.75 m along the corridor outside the room, the door, window, bedside, and the wall of the shower room were monitored with a Nal scintillation survey meter, which was used to obtain readings of the ambient radiation level in six directions, and the mean value for each area was recorded. In addition, areas that were suspected to be highly contaminated, including the toilet bowl, toilet sink, bed head, back of the bed, sink, trash box, and the patient's pillow, were monitored for total surface contamination with a GM survey meter. Furthermore, the toilet's U-bend, toilet sink, bed guard, table, shielding, sink plug, and door knob were swabbed for monitoring removable surface contamination, which was measured using a well counter. CONCLUSION: Ambient radiation monitoring in an I isolation room showed that there was negligible risk of harm in terms of the occupational radiation dose level after patients were released. The ambient radiation dose rate was higher near the door because the sink and trash box were located nearby. The toilet bowl, the toilet's U-bend, and the area around the sink exhibited heavy surface contamination, so these areas require cautious hygiene management.

Usefulness of FDG PET/CT derived parameters in prediction of histopathological finding during the surgery in patients with pancreatic adenocarcinoma.

PURPOSE: Pancreatic cancer is the 4th most common cause of cancer death in Japan and exhibits a 5-year overall survival rate of approximately 7%. The accurate diagnosis of pancreatic cancer is important for determining the optimal management strategy. Fludeoxyglucose-positron emission tomography (FDG PET) integrated with computed tomography (18F-FDG PET/CT) has emerged as a powerful imaging tool for detecting and evaluating various cancers, and it is used for staging, detecting local recurrence and distant metastasis, measuring therapeutic effects, and predicting prognosis in pancreatic cancer patients. Lately, FDG PET/CT-derived parameters, such as standardized uptake values (SUV), the metabolic tumor volume (MTV), and total lesion glycolysis (TLG), have been suggested as prognostic factors for various types of cancer, including pancreatic cancer. However, there is no consensus regarding the best parameters for evaluating patient prognosis, operability, etc. The purpose of this study was to examine the differences between operable and non-operable pancreatic cancer using FDG PET/CT-derived parameters, and to investigate whether volumetric parameters (TLG and the MTV) are superior to SUV-based parameters for predicting infiltration status/determining operability. MATERIALS AND METHODS: We conducted a retrospective study of the cases of 48 patients with clinically proven pancreatic adenocarcinoma, who underwent FDG PET/CT imaging before treatment. In the operable group, the surgical specimens were subjected to histopathological examinations, and the cases were separated into those exhibiting less and greater infiltration. SUVmax, SUVpeak, the tumor background ratio (TBR), TLG, and the MTV were compared between these groups as well as between the operable and non-operable groups. RESULTS: Venous infiltration showed significant associations with several metabolic parameters (SUVmax, SUVpeak, and the TBR). However, it did not display any significant associations with volumetric parameters, such as TLG or the MTV. None of the FDG PET/CT-derived parameters exhibited significant associations with lymphatic or neural infiltration. Significant differences in volumetric parameters, such as the MTV and TLG, were detected between the operable and non-operable subgroups. CONCLUSIONS: Metabolic 18F-FDG PET/CT-derived parameters, such as SUVmax, SUVpeak, and the TBR, are useful for predicting venous infiltration status in patients with operable pancreatic adenocarcinoma.