Role of magnetic resonance vessel wall imaging in detecting and managing ruptured aneurysms among multiple intracranial aneurysms.

BACKGROUND: Wall enhancement of intracranial saccular aneurysms in high-resolution magnetic resonance vessel wall imaging (MR-VWI) might indicate a ruptured aneurysm. Therefore, this study aimed to determine the diagnostic ability of wall enhancement to detect the ruptured aneurysms among multiple aneurysms. METHODS: Patients with subarachnoid hemorrhage (SAH) and multiple intracranial aneurysms who underwent MR-VWI before craniotomy and clipping were included in the study. Three-dimensional T1-weighted fast spin-echo sequences were obtained before and after gadolinium injection. Aneurysm rupture was estimated based on the subarachnoid clot distribution, aneurysmal contours, and MR-VWI findings. We selectively performed surgical clipping and confirmed the rupture site intraoperatively. RESULTS: Thirteen patients with SAH with 13 ruptured and 17 unruptured aneurysms were treated at out facility. The accuracy rate of rupture site diagnosis using MR-VWI was 69.2% (9/13 cases). Each unruptured aneurysm was equally or more strongly enhanced in the other four cases than the ruptured aneurysms. In three of the four unruptured aneurysms with positive MR-VWI findings, atherosclerosis of the aneurysmal wall was observed during simultaneous or elective clipping surgery. Further, clipping surgery was performed without intraoperative rupture in two cases with the help of MR-VWI findings. CONCLUSION: Correct diagnosis of the rupture site using MR-VWI alone was unreliable due to false positives caused by the wall enhancement of unruptured aneurysms with atherosclerosis. Therefore, ruptured aneurysms should be detected using more information in addition to MR-VWI images. MR-VWI may be advantageous to determine surgical strategies when managing patients with SAH and multiple aneurysms.

Prediction of an oxygen extraction fraction map by convolutional neural network: validation of input data among MR and PET images.

PURPOSE: Oxygen extraction fraction (OEF) is a biomarker for the viability of brain tissue in ischemic stroke. However, acquisition of the OEF map using positron emission tomography (PET) with oxygen-15 gas is uncomfortable for patients because of the long fixation time, invasive arterial sampling, and radiation exposure. We aimed to predict the OEF map from magnetic resonance (MR) and PET images using a deep convolutional neural network (CNN) and to demonstrate which PET and MR images are optimal as inputs for the prediction of OEF maps. METHODS: Cerebral blood flow at rest (CBF) and during stress (sCBF), cerebral blood volume (CBV) maps acquired from oxygen-15 PET, and routine MR images (T1-, T2-, and T2*-weighted images) for 113 patients with steno-occlusive disease were learned with U-Net. MR and PET images acquired from the other 25 patients were used as test data. We compared the predicted OEF maps and intraclass correlation (ICC) with the real OEF values among combinations of MRI, CBF, CBV, and sCBF. RESULTS: Among the combinations of input images, OEF maps predicted by the model learned with MRI, CBF, CBV, and sCBF maps were the most similar to the real OEF maps (ICC: 0.597 ± 0.082). However, the contrast of predicted OEF maps was lower than that of real OEF maps. CONCLUSION: These results suggest that the deep CNN learned useful features from CBF, sCBF, CBV, and MR images and predict qualitatively realistic OEF maps. These findings suggest that the deep CNN model can shorten the fixation time for 15O PET by skipping 15O2 scans. Further training with a larger data set is required to predict accurate OEF maps quantitatively.

[Evaluating Eye Lens Dose of Neurovascular and Cardiac Electrophysiology Interventional Physician].

PURPOSE: The International Commission on Radiological Protection recommended that interventional radiologies (IRs) have high radiation doses and that staff may also be exposed to high doses. In the present study, we measured the radiation exposure dose [3 mm dose equivalent, Hp (3) ] in the eye using an appropriate dosimeter placed next to the physician' s eye during neurovascular intervention procedure (Neuro-IR) and interventional cardiac electrophysiology procedure (EP-IR). METHOD: Physicians wore a direct eye dosemeter just lateral to the left eye and an additional direct eye dosemeter outside the radiation protective glasses close to their left eye. Additionally, a neck badge [0.07 mm dose equivalent, Hp (0.07) ] was worn outside the protective apron to the left of the neck, to compare the direct eye dosimeter estimated doses. The occupational eye lens dose was evaluated over a period of 6-month. RESULTS: The maximum Hp (3) of the Neuro-IR physician was estimated 5.1 mSv without the radiation protective glasses and 1.6 mSv with the radiation protective glasses. On the other hand, the maximum Hp (3) of the EP-IR physician was estimated 29 mSv without the radiation protective glasses and 15 mSv with the radiation protective glasses. CONCLUSION: Physicians eye lens dose [Hp (3) ] tended to be overestimated by the neck badge measurements [Hp (0.07)]. A correct evaluation of the lens dose [Hp (3) ] using the direct eye dosimeter is recommended. Although we found a positive correlation between Hp (0.07) and Hp (3), the value of R2 in the regression equation is low, we recommended that the eye lens dose estimated carefully from Hp (0.07).

OCCUPATIONAL RADIATION EXPOSURE DOSE OF THE EYE IN DEPARTMENT OF CARDIAC ARRHYTHMIA PHYSICIAN.

Interventional radiology (IR) procedures tend to be complex, which delivers high radiation exposure to patient. In the present study, we measured the radiation exposure dose [Hp(3)] in the eye using a direct eye dosemeter placed next to the physician's eye during procedures. Physicians wore a direct eye dosemeter just lateral to eyes and an additional direct eye dosemeter outside the radiation protective eyeglasses close to their eyes. Additionally, a neck glass badge was worn at the neck. Although we found a positive correlation between the left neck glass badge dose [Hp(0.07)] and the left eye lens dose [Hp(3)], the value of R2 of the regression equation were 0.62 and 0.71 (outside and inside). We thought that the exact eye lens dose might not be estimated from the neck glass badge. In conclusion, a correct evaluation of the lens dose [Hp(3)] using the direct eye dosemeter is recommended for tachyarrhythmia physicians.

OCCUPATIONAL RADIATION EXPOSURE OF THE EYE IN NEUROVASCULAR INTERVENTIONAL PHYSICIAN.

Neurovascular interventional radiology (neuro-IR) procedures tend to require an extended fluoroscopic exposure time and repeated digital subtraction angiography. To evaluate the actual measurement of eye lens dose using a direct eye dosemeter in neuro-IR physicians is important. Direct dosimetry using the DOSIRIS™ (IRSN, France) [3 mm dose equivalent, Hp(3)] was performed on 86 cases. Additionally, a neck personal dosemeter (glass badge) [0.07 mm dose equivalent, Hp(0.07)] was worn outside the protective apron to the left of the neck. The average doses per case of neuro-IR physicians were 0.04 mSv/case and 0.02 mSv/case, outside and inside the radiation protection glasses, respectively. The protective effect of radiation protection glasses was approximately 60%. The physician eye lens dose tended to be overestimated by the neck glass badge measurements. A correct evaluation of the lens dose [Hp(3)] using an eye dosemeter such as DOSIRIS™ is needed for neuro-IR physicians.

Hyperpolarized (129)Xe spectra from C6 glioma cells implanted in rat brains.

Tumor cell density is dramatically different from normal tissue. Since the chemical shift of hyperpolarized (129)Xe reflects local cell structure, we hypothesized that the presence of tumor cells could potentially be determined from (129)Xe spectra. Spectra and washout decay rate from three rats implanted with C6 glioma cells were compared with eight control rats. No significant differences between normal and tumor spectra were observed. The decay time of the C6 rats (mean 13.5 ± 1.9 s) was not significantly different from normal rats (mean 11.7 ± 1.8 s). These results suggest that hyperpolarized Xe may not be a superior tracer for detection of tumor cells in the intact brain.

Hypertrophic olivary degeneration after surgical resection of brain tumors.

BACKGROUND: Hypertrophic olivary degeneration (HOD) can be seen as high signal intensity with enlargement of the inferior olivary nucleus (ION) on T2-weighted magnetic resonance (MR) images 4-6 months after injury of the Guillain-Mollaret triangle. To the best of our knowledge, there has been no systematic evaluation with regard to the relationship between neurosurgical intervention affecting this pathway and the appearance of HOD. PURPOSE: To evaluate MR findings of HOD after surgical resection of brain tumors with the temporal evolution in focus. MATERIAL AND METHODS: MR images of seven patients that showed signal changes in the ION after surgical resection of brain tumors in the posterior fossa were retrospectively reviewed. T1-weighted imaging with and without gadolinium (Gd) contrast enhancement and T2-weighted imaging were performed in all patients before and after surgery. RESULTS: Before surgery, no patient had a signal change in the ION. T2-high signal intensity of the ION initially appeared 5 days to 2.5 months after surgery. Five patients showed enlargement of the ION with T2-high signal intensity 11 days to 3.5 months after surgery: three patients showed the enlargement of the ION subsequent to the T2-signal change on serial follow-up MR images. On Gd-enhanced T1-weighted images, there was no enhancement at the ION in any patient. Each signal change of the ION was consistent with HOD, according to the relationship between the resection site of the tumor and the Guillain-Mollaret triangle on follow-up MRI. CONCLUSION: HOD can be caused after neurosurgical intervention of brain tumors involving the Guillain-Mollaret triangle. It is important for radiologists to distinguish HOD from tumor recurrence.

Hypertrophic olivary degeneration after gamma-knife radiosurgery for pontine metastasis.

We present a case of a 57-year-old woman who underwent gamma-knife radiosurgery (GKRS) for pontine metastasis. Magnetic resonance (MR) imaging 2.8 months after GKRS showed T2 hyperintensity and hypertrophy of the left inferior olivary nucleus (ION) without gadolinium enhancement and smaller pontine metastasis. We diagnosed the signal change in the left ION as hypertrophic olivary degeneration (HOD) resulting from damage to the left central tegmental tract. We believe this is the first report to describe HOD after GKRS for pontine metastasis.

F-18 FDG-PET imaging of dysembryoplastic neuroepithelial tumor-like astrocytoma.

Cerebral astrocytoma needs to be distinguished from dysembryoplastic neuroepithelial tumor (DNT) when a well-demarcated, cortically based and pseudo-cystic tumor with minimal mass effect is demonstrated on magnetic resonance imaging. We report an unusual case of DNT-like astrocytoma. 18F fluoro-deoxy-glucose (FDG) positron emission tomography showed a focal increase of FDG uptake in a deep part of the tumor. Histologic examination revealed predominantly microcystic change with oligodendrocyte-like cells, leading to a diagnosis of DNT. However, increased cellularity and nuclear atypia of astrocytes within the tumor were conspicuous as for DNT. Four years after excision, tumor recurrence was detected. FDG-positron emission tomography is useful for identifying the malignant potential of DNT-like astrocytoma.

Low-grade fibromyxoid sarcoma of the small bowel mesentery: computed tomography and magnetic resonance imaging findings.

Low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor that commonly arises in the lower extremities but rarely in the mesentery. We report computed tomography (CT) and magnetic resonance imaging (MRI) findings of LGFMS of the small bowel mesentery. On CT, the mass was composed of two components. One component, on its right side, appeared to have isointense attenuation relative to muscle, whereas the other component, on its left side, appeared to have low attenuation. On MRI the mass on the right side showed hypointensity similar to muscle on both T1-and T2-weighted images as well as mostly slight enhancement on contrast-enhanced T1-weighted images. On the other hand, the mass on the left side showed relative hypointensity on T1-weighted images and hyperintensity on T2-weighted images as well as intense enhancement on contrast-enhanced T1-weighted images, suggesting that the tumor contained myxoid tissue. The myxoid area of LGFMS may have a tendency to reveal intense enhancement on contrast-enhanced images.

CT-guided transthoracic needle biopsy using a puncture site-down positioning technique.

OBJECTIVE: We have developed a new CT-guided technique using puncture site-down positioning during the biopsy. The goal of our study was to determine the efficacy and safety of this technique for biopsy of lung lesions compared with the standard technique. MATERIALS AND METHODS: Medical records of 236 patients who underwent CT-guided transthoracic needle biopsy were retrospectively evaluated. This study included 89 cases that were biopsied using the standard technique (group A) and 147 cases that were biopsied using the puncture site-down positioning technique (group B). A 20-gauge automated cutting needle without coaxial technique was used in all patients. Medical records were reviewed for lesion size and location, biopsy results, and complications. RESULTS: When using the standard technique, the sensitivity for malignant lesions was 96.1%; the sensitivity for benign lesions, 92.1%; and diagnostic accuracy, 94.4%. Thirty-seven patients (41.6%) had pneumothorax, with 16 (18.0%) requiring chest tube placement. When using the puncture site-down positioning technique, the sensitivity for malignant lesions was 95.4%; the sensitivity for benign lesions, 93.3%; and diagnostic accuracy, 94.6%. Nineteen patients (12.9%) had pneumothorax, with four (2.7%) requiring chest tube placement. Other complications were minimal. CONCLUSION: CT-guided transthoracic needle biopsy using the puncture site-down positioning technique is an effective and safe procedure with a high diagnostic accuracy and low complication rate. This new technique is especially useful in reducing the rate of pneumothorax.

[A case of synovial sarcoma in the submandibular region].

Synovial sarcomas are a less common cervical tumor in young patients. We report a 23-year-old man with synovial sarcoma in the submandibular region. T2-weighted MR images demonstrated a mixed-intensity tumor attached to the submandibular gland. T1-weighted MR images revealed a focal area with mildly increased signal intensity, indicating intratumoral hemorrhage. MR images were also useful for visualization of tumor extension. Synovial sarcoma should be considered in the differential diagnosis of well-defined inhomogeneous tumors adjacent to the submandibular gland in young adults.

Clinically silent choroid plexus cyst: evaluation by diffusion-weighted MRI.

We retrospectively reviewed diffusion-weighted magnetic resonance images of 57 patients with a choroid plexus cyst diagnosed by contrast-enhanced T1-weighted imaging. All the cysts appeared to represent incidental findings. Thirty-eight of 57 patients had bilateral cysts and 19 had unilateral ones. On diffusion-weighted images, 78 of 95 cysts showed homogeneously high signal intensity, 12 showed focal high signal areas, and 5 had no portion with a high signal. The apparent diffusion coefficient of the high signal areas in the cysts was (1.46+/-0.14) x10(-3) mm(2)/s, intermediate between the apparent diffusion coefficients of cerebrospinal fluid and cerebral white matter, (3.15+/-0.67) x10(-3) and (0.79+/-0.22) x10(-3) mm(2)/s, respectively. Pathological correlation was available in one case, showing high signal intensity areas in the glomera of the choroid plexuses in the lateral ventricles on diffusion-weighted images corresponding to gelatinous cysts with highly proteinaceous content.

Role of KL-6 in evaluating the disease severity of rheumatoid lung disease: comparison with HRCT.

OBJECTIVE: To determine the role of KL-6 (Krebs von den Lungen-6) in evaluating the disease severity of pulmonary lesions in rheumatoid arthritis (RA) compared with high resolution computed tomography (HRCT) findings. METHODS: Fifty serum KL-6 levels and HRCT images were prospectively obtained from 47 RA patients. Eight HRCT findings were classified into five grades. Patients were also divided into two groups according to the KL-6 threshold level and HRCT findings were evaluated. RESULTS: There was a positive correlation between the serum KL-6 level and the total CT score (r = 0.83). Reticular opacity most closely related to the serum KL-6 levels (r = 0.84). In the high KL-6 group (n = 10), the average CTscore was markedly increased (64.6 points) and severe honeycombing expanded into the whole lung. One case revealed diffuse ground glass opacity. In 12 of 40 cases in the normal KL-6 group, CT scores mildly increased compared with the other cases (over 20 points). The predominant finding of these cases could be classified into four types: (1) narrow spread honeycombing; (2) subtle fibrosis; (3) airway diseases; and (4) dense consolidation. CONCLUSION: KL-6 is a useful marker to detect severe RA lung disease. It is also useful to distinguish non-fibrosis from fibrosis predominant cases. However, it sometimes could not detect early stage RA lung disease.

MR imaging findings of parotid tumors with pathologic diagnostic clues: a pictorial essay.

This pictorial essay depicts MR features of benign and malignant parotid tumors. Increased T2 signal intensity is suggestive of pleomorphic adenoma. Tumors with relatively low signal intensity on T2-weighted images are more likely to be malignant even when they are well-demarcated. Fat suppression technique improves the ability to define the boundaries of neoplatic or inflammatory lesions.

Multicystic acoustic schwannoma with intratumoral hemorrhage: a report of two cases.

We encountered two multicystic acoustic schwannomas with intratumoral hemorrhage. The radiological appearance in each case was similar to that obtained with CT and MRI. From a histological perspective, in each case we observed hypervascularity with thin-walled, dilated vessels in clusters and hemosiderin depositions around the dilated vessels.

[CT and MR imaging of gynecological emergency disease].

We describe the CT and MRI findings of gynecologic emergency diseases: pelvic inflammatory disease, ectopic pregnancy, ovarian hemorrhage, ovarian torsion, rupture of ovarian tumor, eclampsia, and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome. Diagnostic keys to these diseases are presented in this review. CT and MRI play a complementary role to sonography in accurately diagnosing these diseases. In situations that require an exact, immediate diagnosis, radiologists should be familiar with the key imaging findings.

Transneuronal degeneration in patients with temporal lobe epilepsy: evaluation by MR imaging.

The aim of this study was to assess the MR imaging findings of transneuronal degeneration of limbic system in the patients with temporal lobe epilepsy, and to detect the influence of surgery on the anatomy of the limbic system. Axial and coronal T1- and T2-weighted MR images were retrospectively analyzed in 34 patients with temporal lobe epilepsy, focusing on transneuronal degeneration. In 17 of the 34 patients, MR images were also analyzed after selective amygdalo-hippocampectomy. Atrophy of the fornix, mamillary body, mamillothalamic tract (MTT), and thalamus ipsilateral to the epileptic focus was demonstrated on MR images in 14.7, 17.6, 8.8, and 11.8% of the 34 patients, respectively. Focal hyperintensity of the thalamus was found on T2-weighted images in 8.8% of the 34 patients. In 17 patients who were evaluated before and after surgery, transneuronal degeneration was seen more frequently after surgery: fornix (11.8 vs 29.4%), mamillary body (11.8 vs 52.9%), MTT (5.9 vs 11.8%), and thalamus (11.8 vs 11.8%). Transneuronal degeneration of the limbic system is clearly demonstrated by MR imaging in patients with temporal lobe epilepsy, and surgical intervention induces transneuronal degeneration more frequently.

Regional changes in human cerebral blood flow during dipyridamole stress: neural activation in the thalamus and prefrontal cortex.

Intravenous dipyridamole increases the concentration of circulating adenosine and produces coronary vasodilation. However, it decreases global cerebral blood flow (CBF) due to hyperventilation side effect of adenosine. In the present study, changes in regional CBF during dipyridamole stress were identified in detail. In 11 healthy men (51-71 years of age), CBF was measured by positron emission tomography with oxygen-15-labeled water at rest (baseline) and during dipyridamole stress. All images were normalized to global CBF and transformed to standard brain anatomy. A t map between baseline and dipyridamole stress conditions was then created on a pixel-by-pixel basis. CBF was globally decreased during dipyridamole stress. However, a significant relative increase in CBF was observed bilaterally in the thalamus and prefrontal cortex, indicating neural activation in these regions. Adenosine plays an important role in the production of anginal pain by stimulation of A(1) adenosine receptors. Neural activation in the thalamus and prefrontal cortex during angina pectoris has been reported. Although no subject felt chest pain during dipyridamole stress, neural activation in the thalamus and prefrontal cortex indicates that stimulation of A(1) adenosine receptors during dipyridamole stress may produce input from the heart to the thalamus through the vagal fiber.