The Development of a Composite Thin Film Barrier of Tungsten Fe3O4-rGO (FerGO) for the Radiation Shielding of Medical Personnel.

Tungsten is the most effective eco-friendly material used for radiation shielding in hospitals. However, despite its commendable density and shielding performance, tungsten faces challenges in miscibility with other materials because of its elevated melting point and strength. In this study, to protect medical personnel against scattered rays, which are indirect X-rays, a lightweight material was prepared by mixing graphite oxide material, considering its thinness and flexibility. Tungsten particles were evenly dispersed in the polymer, and nanofibers were prepared using this blended polymer solution via electrospinning. Concurrently, the process technology was explored to craft a thin film sheet and obtain a lead-like shielding effect. A spinning solution was prepared by mixing Fe3O4-rGO (FerGO) and tungsten. At 60 kVp, 0.1 mm was measured as 0.097 mmPb, at 80 kVp, 0.2 mm was measured as 0.196 mmPb, and at 100 kVp, 0.3 mm was measured as 0.279 mmPb, showing similar shielding performance to lead. As density directly affects the shielding effect, graphene oxide played an important role in increasing the density of the material from 1.941 g/cm3 to 2.302 g/cm3. Thus, this study provides an effective process for producing thin film sheets equivalent to lead.

Differentiation of postoperative changes and residual tumors in dynamic contrast-enhanced sella MRI after transsphenoidal resection of pituitary adenoma.

To establish magnetic resonance imaging (MRI) features that differentiate residual tumors from postoperative surgical changes following the transsphenoidal approach of a pituitary adenoma.We analyzed residual enhancements at the tumor bed in 52 patients who underwent dynamic contrast-enhanced sella MRI within 48 hours after surgery and at 6 to 28 months. Patients were divided into 2 groups defined by either peripheral or nodular enhancement patterns. For each group, we measured the maximum thickness of the residual enhancing portion and compared differences in the residual tumor and postoperative changes.Among the tumors examined in the 52 patients, 19 residual tumors showed nodular (n = 16) and peripheral (n = 3) enhancement patterns, and 33 postoperative changes showed nodular (n = 3) and peripheral (n = 30) enhancement patterns. The mean residual tumor thickness was 7.1 mm (range, 2.9-16.8 mm) and 1.9 mm (range, 1.0-7.4 mm) in the postoperative change. Receiver operating characteristic curve analysis revealed that a 3.9-mm thickness was associated with 89% sensitivity, 97% specificity, and 94% accuracy for diagnosis of residual tumor.On immediate postoperative MRI, residual enhancement with greater than 3.9-mm thickness and nodular pattern suggest residual pituitary adenoma tumor.

Predictive Factors for Response of Intracranial Dural Arteriovenous Fistulas to Transarterial Onyx Embolization: Angiographic Subgroup Analysis of Treatment Outcomes.

OBJECTIVE: Endovascular treatment using Onyx has been increasingly used to treat intracranial dural arteriovenous fistulas (DAVFs). This study evaluated predictive factors for favorable treatment outcome in patients with intracranial noncavernous DAVFs treated by transarterial Onyx embolization. METHODS: Between August 2008 and August 2014, 55 patients who underwent transarterial Onyx embolization for noncavernous DAVFs were retrospectively reviewed. Patients' demographic, clinical, and procedural data were analyzed to find statistically significant predictive factors for favorable treatment outcomes after Onyx embolization. Fistulas were classified angiographically according to the relationship between fistulas and dural venous sinuses and the presence of leptomeningeal venous reflux. RESULTS: Sixty-eight Onyx embolizations were performed in 55 patients. Immediate angiographic cure was achieved in 28 patients, and 14 of 27 patients with residual shunts showed progressive occlusion at follow-up imaging studies. Therefore, the overall favorable treatment outcome was 76.4% (42/55). The remaining 13 patients (23.6%) showed persistent residual shunts, and 3 (5.5%) of them showed aggravation of residual lesion on follow-up studies. Of 25 patients with non-sinus fistulas, 23 patients (92%) showed favorable treatment outcomes, and 19 of 30 patients (63.3%) with sinus fistulas showed favorable outcomes. Among the evaluated variables, non-sinus DAVFs was a statistically significant predictive factor for favorable response to transarterial Onyx embolization (P < 0.05). CONCLUSIONS: Transarterial Onyx embolization is a highly effective treatment method for non-sinus DAVFs. Careful consideration of angiographic features and multimodal embolization strategies are required for treatment of sinus DAVFs.

Analysis of the layering pattern of the apparent diffusion coefficient (ADC) for differentiation of radiation necrosis from tumour progression.

OBJECTIVES: To evaluate the added value of diffusion-weighted imaging (DWI) to perfusion-weighted imaging (PWI) for differentiating tumour progression from radiation necrosis. METHODS: Sixteen consecutive patients who underwent removal of a metastatic brain tumour that increased in size after stereotactic radiosurgery were retrospectively reviewed. The layering of the ADC was categorised into three patterns. ADC values were measured on each layer, and the maximum rCBV was measured. rCBV and the layering pattern of the ADC of radiation necrosis and tumour progression were compared. RESULTS: Nine cases of radiation necrosis and seven cases of tumour progression were pathologically confirmed. Radiation necrosis (88.9 % vs. 14.3 %) showed a three-layer pattern of ADC with a middle layer of minimum ADC more frequently. If rCBV larger than 2.6 was used to differentiate radiation necrosis and tumour progression, the sensitivity was 100 % but specificity was 56 %. If the lesions with the three-layer pattern of ADC with moderately increased rCBV (2.6-4.1) were excluded from tumour progression, the sensitivity and specificity increased to 100 %. CONCLUSIONS: The three-layer pattern of ADC shows high specificity in diagnosing radiation necrosis; therefore, combined analysis of the ADC pattern with rCBV may have added value in the correct differentiation of tumour progression from radiation necrosis.

Local intraarterial tirofiban after formation of anterograde flow in patients with acute ischemic stroke: preliminary experience and short term follow-up results.

OBJECTIVE: Despite the risk of intracranial hemorrhage, combination therapy with intravenous recombinant tissue plasminogen activator and intraarterial mechanical thrombolysis can be effective for treatment of acute ischemic stroke. We investigated the feasibility and safety of intraarterial tirofiban following formation of anterograde flow after mechanical thrombolysis in acute ischemic stroke. METHODS: We analyzed data from consecutive patients with acute ischemic stroke, who underwent treatment with intraarterial thrombolysis. All patients were evaluated immediately and 7 days later by computed tomography scanning and magnetic resonance imaging scanning with magnetic resonance angiography. For clinical outcome analysis, we followed up the NIHSS score and modified Rankin Scale score during a period of 3 months. RESULTS: Sixteen patients underwent treatment. The mean baseline NIHSS score was 16.1 ± 4.4 points. 75.1% of patients showed angiographic improvement; 43.8% and 31.3% had complete and partial recanalization, respectively. 53.3% and 56.3% showed clinical improvement and favorable outcome at 24 h and 3 months, respectively. One patient had symptomatic intracranial hemorrhage. CONCLUSIONS: Our results suggest that administration of local intraarterial tirofiban after anterograde flow formation is a viable treatment strategy for patients of acute ischemic stroke for reducing the risk of reocclusion after intraarterial thrombolysis.

Digital tomosynthesis for PNS evaluation: comparisons of patient exposure and image quality with plain radiography.

OBJECTIVE: We investigated low dose digital tomosynthesis (DT) for the evaluation of the paranasal sinus (PNS), and compared its diagnostic accuracy with a PNS radiography series (XR). MATERIALS AND METHODS: We enrolled 43 patients for whom XR, PNS DT, and OMU CT were performed. We measured effective doses (EDs) of XR, DT, and OMU CT using Monte Carlo simulation software. Two radiologists performed independent observation of both XR and DT. For seven PNSs, they scored anatomic conspicuity of sinuses and confidence on the presence of sinusitis using nine point scales. OMU CT was observed by the third radiologist and the findings were regarded as reference standard. We compared scores for conspicuity and sinusitis confidence between XR and DT. RESULTS: Mean EDs were 29 ± 6 µSv, 48 ± 10 µSv, and 980 ± 250 µSv, respectively, for XR, DT, and CT. Mean scores for conspicuity were 6.3 and 7.4, respectively, for XR and DT. Sensitivity per patient basis for sinusitis detection were 52% and 96%, respectively, for XR and DT in observer 1 (p = 0.001) and 80% and 92% for observer 2 (p = 0.25). Specificities for sinusitis exclusion were 100% for both XR and DT for observer 1 and 89% and 100% for observer 2 (p = 0.50). Accuracies for sinusitis diagnosis were 72% and 98%, respectively, for XR and DT for observer 1 (p = 0.001) and 84% and 95% for observer 2 (p = 0.125). CONCLUSION: Patient radiation dose from low dose DT is comparable with that of PNS XR. Diagnostic sensitivity of DT for sinusitis was superior to PNS XR.

Usefulness of the dynamic gadolinium-enhanced magnetic resonance imaging with simultaneous acquisition of coronal and sagittal planes for detection of pituitary microadenomas.

OBJECTIVE: Does dynamic gadolinium-enhanced imaging with simultaneous acquisition of coronal and sagittal planes improve diagnostic accuracy of pituitary microadenomas compared with coronal images alone? METHODS: Fifty-six patients underwent 3-T sella MRI including dynamic simultaneous acquisition of coronal and sagittal planes after gadolinium injection. According to conspicuity, lesions were divided into four scores (0, no; 1, possible; 2, probable; 3, definite delayed enhancing lesion). Additional information on supplementary sagittal images compared with coronal ones was evaluated with a 4-point score (0, no; 1, possible; 2, probable; 3, definite additional information). Accuracy of tumour detection was calculated. RESULTS: Average scores for lesion detection of a combination of two planes, coronal, and sagittal images were 2.59, 2.32, and 2.18. 6/10 lesions negative on coronal images were detected on sagittal ones. Accuracy of a combination of two planes, of coronal and of sagittal images was 92.86%, 82.14% and 75%. Six patients had probable or definite additional information on supplementary sagittal images compared with coronal ones alone (10.71%). CONCLUSION: Dynamic MRI with combined coronal and sagittal planes was more accurate for detection of pituitary microadenomas than routinely used coronal images. Simultaneous dynamic enhanced acquisition can make study time fast and costs low. KEY POINTS: We present a new dynamic MRI technique for evaluating pituitary microadenomas • This technique provides simultaneous acquisition of contrast enhanced coronal and sagittal images. • This technique makes the diagnosis more accurate and reduces the examination time. • Such MR imaging only requires one single bolus of contrast agent.

Trigeminal neuralgia: assessment with T2 VISTA and FLAIR VISTA fusion imaging.

OBJECTIVE: To evaluate the neurovascular compression (NVC) in patients with trigeminal neuralgia (TN) using T2 VISTA and FLAIR VISTA fusion imaging. METHODS: Sixty-six consecutive patients with TN who underwent MR imaging at 3-T between April 2008 and December 2010 were retrospectively reviewed. Multiplanar reconstructions (MPR) of T2 VISTA and FLAIR VISTA fusion imaging were used for image interpretation. The frequency of vascular contact, the segment of compression and the type of vessel were compared between the ipsilateral symptomatic side and the contralateral asymptomatic side. RESULTS: The frequency of vascular contact on the ipsilateral side and the contralateral side were 95.5% (63/66) and 74.2% (49/66), respectively. The frequency of indentation on the ipsilateral side and contralateral side were 74.2% (49/66) and 21.2% (14/66), and showed a statistically significant difference (p < 0.05). The sensitivity, specificity and odds ratio were 77.8%, 71.4% and 10.7, respectively. There were no significant differences in the involved segment or type of vessel between the ipsilateral side and contralateral side. CONCLUSION: MPR of T2 VISTA and FLAIR VISTA fusion imaging is useful in the detection of NVC in patients with TN. Vascular indentation can predict the presence of symptoms in patients with TN. Key Points •Fusion MRI with multiplanar reconstruction can detect neurovascular compression in patients with trigeminal neuralgia •Vascular indentation can predict the presence of symptoms in patients with trigeminal neuralgia •In patients with trigeminal neuralgia, neurovascular indentation is commoner on the symptomatic side.

Endovascular coil embolization of very small intracranial aneurysms.

OBJECTIVE: We aimed to evaluate the results of endovascular coil embolization for very small aneurysms (or= 4), with no bleeding of the treated aneurysms during a mean follow-up period of 13.3 months. On 27 follow-up MRA, there was no recurrence, and the five incompletely occluded aneurysms showed a spontaneous amelioration resulting in an adequate occlusion. CONCLUSION: Coil embolization of very small aneurysms is technically feasible with good results. The long-term efficacy and the potential as a standard treatment strategy remain to be determined by randomized large trials.

Endovascular treatment of a ruptured accessory middle cerebral artery aneurysm.

A 51-year-old female presented with bilateral accessory middle cerebral arteries (MCA) with associated ruptured aneurysm manifesting as a subarachnoid hemorrhage. Angiography demonstrated the bilateral accessory MCA and associated ruptured aneurysm at the junction of the left anterior cerebral artery and left accessory MCA. This was successfully treated by coil embolization. Magnetic resonance angiography obtained 6 months later revealed no evidence of residual or recurring aneurysm.

Infratentorial oligodendrogliomas: Imaging findings in six patients.

BACKGROUND: Oligodendrogliomas are primarily supratentorial tumors. However, infrequently, they can also arise from infratentorial structures. There are only limited numbers of radiological articles on the specific imaging findings of this entity. PURPOSE: To investigate the imaging findings of infratentorial oligodendrogliomas. MATERIAL AND METHODS: We retrospectively reviewed the magnetic resonance imaging (MRI) findings and clinical records of six patients with pathologically proven infratentorial oligodendrogliomas between December 1994 and April 2008. Tumor location, circumscription, signal intensity (SI), enhancement pattern, the presence of restricted diffusion, and the change of the relative cerebral blood volume (rCBV) on MRI were evaluated. RESULTS: In total, six patients (three male, three female; mean age 65 years, range 51-75 years) were included. The pathology revealed anaplastic oligodendrogliomas in all six patients. The location was cerebellum in four patients, medulla in one patient, and fourth ventricle and tegmentum in one patient. Three of them were of the infiltrative type, and the other three of the mass-forming type. The solid component of the tumors showed high SI (n=6) on FLAIR and T2-weighted images, and low (n=5) or iso (n=1) SI on T1-weighted images. All infiltrative lesions showed multifocal patchy enhancement, and mass-forming lesions showed heterogeneous enhancement (n=2) and diffuse homogeneous enhancement (n=1). Three patients had restricted diffusion, and one had leptomeningeal seeding. There was markedly increased rCBV on perfusion-weighted image (PWI) in one patient. Calcification or hemorrhage was not found. Tumor progression after operation, radiation therapy, gamma-knife surgery, or chemotherapy developed in five patients. CONCLUSION: Although infratentorial oligodendrogliomas did not show characteristic imaging findings, there was a tendency toward multifocal heterogeneous enhancement and absent or mild mass effect of infiltrative lesions. Infratentorial oligodendrogliomas may be more malignant than supratentorial oligodendrogliomas.

Signal intensity change of the labyrinth in patients with surgically confirmed or radiologically diagnosed vestibular schwannoma on isotropic 3D fluid-attenuated inversion recovery MR imaging at 3 T.

OBJECTIVE: The purpose of this study was to evaluate the signal intensity (SI) change of the labyrinth in patients with vestibular schwannoma on isotropic 3D fluid-attenuated inversion recovery (FLAIR) imaging at 3 T. METHODS: Thirty-four patients with surgically confirmed or radiologically diagnosed vestibular schwannoma were included in this study. Retrospectively, we visually and quantitatively compared the SIs of the cochlea and vestibule on the affected side with those on the unaffected side. We also investigated whether there was correlation between the SI ratios (SIRs) of the labyrinth and the audiometric findings. RESULTS: On 3D FLAIR images, the SI of the cochlea and vestibule on the affected side was significantly increased in 97% (33/34) and 91% (31/34), respectively. While the SI of the cochlea was diffusely increased, that of the vestibule was only partially increased. Quantitative study also revealed statistically significantly higher SIRs of the cochlea (0.99 +/- 0.29) and vestibule (0.73 +/- 0.31) on the affected side, compared with the cochlea (0.47 +/- 0.20) and vestibule (0.19 +/- 0.10) on the unaffected side. There was no significant correlation of the SIRs of the labyrinth with the degree of hearing loss. CONCLUSION: In patients with vestibular schwannoma, isotropic 3D FLAIR imaging is a useful method for the evaluation of the SI changes of the labyrinth.

Analysis of perfusion weighted image of CNS lymphoma.

PURPOSE: It is difficult to differentiate CNS lymphoma from other tumors such as malignant gliomas, metastases, or meningiomas with conventional MR imaging, because the imaging findings are overlapped between these tumors. The purpose of this study is to investigate the perfusion weighted MR imaging findings of CNS lymphomas and to compare the relative cerebral blood volume ratios between CNS lymphomas and other tumors such as high grade gliomas, metastases, or meningiomas. MATERIALS AND METHODS: We retrospectively reviewed MRI findings and clinical records in 13 patients with pathologically proven CNS lymphoma between January 2006 and November 2008. We evaluated the relative cerebral blood volume ratios of tumor, which were obtained by dividing the values obtained from the normal white matter on MRI. RESULTS: Total 13 patients (M:F=8:5; age range 46-67 years, mean age 52.3 years) were included. The CNS lymphomas showed relatively low values of maximum relative CBV ratio in most patients regardless of primary or secondary CNS lymphoma. CONCLUSION: Perfusion weighted image may be helpful in the diagnosis of CNS lymphoma in spite of primary or secondary or B cell or T cell.

MRI findings of spinal visceral larva migrans of Toxocara canis.

PURPOSE: The purpose of this study is to investigate the MRI findings of visceral larva migrans (VLS) of Toxocara canis in spinal cord. MATERIALS AND METHODS: We retrospectively reviewed spinal MRI findings in eight patients with serologically proven Toxocara canis between 2005 and 2008. We evaluated the location, length, extent and migration of the lesion, MR signal intensity (SI), enhancement pattern, and swelling of the spinal cord. We evaluated clinical features including presenting symptoms and signs and treatment response. RESULTS: Total 8 patients (M=8; age range 36-79 years) were included. The lesions were located in the cervical or thoracic spinal cord in all patients. All lesions showed high SI and minimal or mild swelling of involved spinal cord on T2WI and focal nodular enhancement on posterior or posterolateral segment of spinal cord. The length of involved lesion was relatively short in most patients. There was a migration of lesion in one patient. In spite of albendazole or steroid treatment, neurological symptoms or signs were not significantly improved in all patients. CONCLUSION: Although all lesions show non-specific imaging findings like non-tumorous myelopathy mimicking transverse myelitis, single lesion, focal nodular enhancement on posterior or posterolateral segment of spinal cord, relatively short segmental involvement and migration of lesion may be characteristic findings of spinal VLM of Toxocara canis. In addition, the reluctant response to the treatment may be characteristic of spinal VLM of Toxocara canis.

Intraventricular meningiomas: radiological findings and clinical features in 12 patients.

PURPOSE: To characterize the computed tomography (CT) and magnetic resonance (MR) imaging findings and clinical features of intraventricular (IV) meningiomas. MATERIALS AND METHODS: CT (n=8) and MR (n=12) images and medical records of 12 patients (five men and seven women; mean age, 36 years; range, 14-68 years) with pathologically proven IV meningiomas were retrospectively reviewed. Particular attention was put on the size and shape of the mass; internal architecture such as necrosis or calcification within the tumor; peritumoral edema; associated hydrocephalus and clinical features such as symptoms, treatment, and prognosis. RESULTS: There were five of benign, three of atypical, and four of malignant subtype. All lesions were located in the lateral ventricle ranging in maximum diameters from 4.0 to 7.3 cm (mean, 5.4 cm). All tumors had lobulated shape. Five (71%, 5/7) of the atypical and malignant IV meningiomas, but just two (40%, 2/5) benign IV meningiomas, had irregular lobulation. The tumors were isointense (n=7) or hypointense (n=5) to gray matter on T1-weighted images, whereas isointense (n=9) or hyperintense (n=3) on T2-weighted images. On gadolinium-enhanced T1-weighted images, homogeneous enhancement was seen in five lesions, and heterogeneous enhancement was seen in seven lesions, Most patients (n=10) had associated localized hydrocephalus due to ventricular entrapment. Intratumoral necrosis was seen in two cases (17%, 2/12), all of these were malignant subtype. In two cases of atypical and malignant subtypes, recurrences were found during the follow-up period after surgical resection. CONCLUSION: More than half (n=7, 58%) of the IV meningiomas were of atypical (n=3) or malignant (n=4) subtype. IV meningiomas tend to have a lobulated shape, especially irregular lobulation, and intratumoral necrosis was frequently seen in the atypical or malignant subtypes.

Ethanol sclerotherapy for the management of craniofacial venous malformations: the interim results.

OBJECTIVE: We wanted to evaluate the safety and feasibility of ethanol sclerotherapy for treating craniofacial venous malformations (CVMs). MATERIALS AND METHODS: From May 1998 to April 2007, 87 patients (40 men and 47 women; age range, 2-68 years) with CVMs underwent staged ethanol sclerotherapy (range, 1-21 sessions; median number of sessions, 2) by the direct puncture technique. Clinical follow up (range, 0-120 months; mean follow up, 35 months; median follow up, 28 months) was performed for all the patients. Therapeutic outcomes were established by evaluating the clinical outcome of the signs and symptoms in all patients, as well as the degree of devascularization, which was determined on the follow-up imaging, in 71 patients. RESULTS: A total of 305 procedures with the use of ethanol were performed in 87 patients. Follow-up imaging studies were performed for 71 of 87 patients. Twenty-three (32%) of the 71 patients showed excellent outcomes, 37 patients (52%) showed good outcomes and 11 patients (16%) showed poor outcomes. Ethanol sclerotherapy was considered effective for 60 patients. All the minor complications such as bulla (n = 5) healed with only wound dressing and observation. Any major complication such as skin necrosis did not develop. CONCLUSION: Percutaneous ethanol sclerotherapy is an effective, safe treatment for CVMs.

18F-FDG PET/CT findings of sinonasal inverted papilloma with or without coexistent malignancy: comparison with MR imaging findings in eight patients.

INTRODUCTION: Sinonasal inverted papilloma (IP) is known for high rate of associated malignancy. The purpose of this study was to identify (18)F-FDG PET/CT findings of sinonasal IPs. We also tried to compare the PET/CT findings with the MR imaging findings. METHODS: We retrospectively reviewed PET/CT and MR images of eight patients with sinonasal IP with (n = 6) or without (n = 2) coexistent squamous cell carcinoma (SCC). Particular attention was paid to correlate the PET/CT findings with the MR imaging findings in terms of area distribution of standard uptake values (SUVs) and a convoluted cerebriform pattern (CCP). RESULTS: In two benign IPs, the maximum SUVs measured 8.2 and 7.8, respectively (mean, 8.0). In both tumors, MR images demonstrated a diffuse CCP. In six IPs with coexistent SCC, the maximum SUVs ranged from 13.3 to 31.9 (mean +/- SD, 20.2 +/- 6.6). In these tumors, MR images demonstrated a diffuse CCP in two, a partial CCP in three, and no CCP in one. A wide discrepancy was noted between MR imaging and PET/CT in terms of area distribution of a CCP and SUVs. CONCLUSION: In sinonasal lesions with MR imaging features of IP, (18)F-FDG PET/CT demonstrating avid FDG uptake does not necessarily imply the presence of coexistent malignancy. In our small series, although IPs containing foci of SCC had consistently higher SUVs than IPs without SCC, the limited literature on this subject suggests that PET cannot be used reliably to make the distinction.

Morphological and functional MRI, MRS, perfusion and diffusion changes after radiosurgery of brain metastasis.

Radiosurgery is a noninvasive procedure where spatially accurate and highly conformal doses of radiation are targeted at brain lesions with an ablative intent. Recently, radiosurgery has been established as an effective technique for local treatment of brain metastasis. After radiosurgery, magnetic resonance (MR) imaging plays an important role in the assessment of the therapeutic response and of any complications. The therapeutic approach depends on the imaging findings obtained after radiosurgery, which have a role in the decision making to perform additional invasive modalities (repeat resection, biopsy) to obtain a definite diagnosis and to improve the survival of patients. Conventional MR imaging findings are mainly based on morphological alterations of tumors. However, there are variable imaging findings of radiation-induced changes including radiation necrosis in the brain. Radiologists are sometimes confused by radiation-induced injuries, including radiation necrosis, that are seen on conventional MR imaging. The pattern of abnormal enhancement on follow-up conventional MR imaging closely mimics that of a recurrent brain metastasis. So, classifying newly developed abnormal enhancing lesions in follow-up of treated brain metastasis with correct diagnosis is one of the key goals in neuro-oncologic imaging. To overcome limitations of the use of morphology-based conventional MR imaging, several physiological-based functional MR imaging methods have been used, namely diffusion-weighted imaging, perfusion MR imaging, and proton MR spectroscopy, for the detection of hemodynamic, metabolic, and cellular alterations. These imaging modalities provide additional information to allow clinicians to make proper decisions regarding patient treatment.

High signal intensity halo around the carotid artery on maximum intensity projection images of time-of-flight MR angiography: a new sign for intraplaque hemorrhage.

PURPOSE: To evaluate the value of the high signal intensity halo sign as a new marker of a fresh or recent intraplaque hemorrhage on the maximum intensity projection (MIP) images of time-of-flight (TOF) MR angiography. MATERIALS AND METHODS: A total of 135 consecutive patients were included in this study. High-resolution MRI using 3-inch surface coils was performed on a 1.5T scanner before the carotid endarterectomy. TOF MR angiograms and T2-weighted, T1-weighted pre- and postcontrast fast spin echo images were obtained. The surgical and pathological findings of the carotid artery were analyzed and correlated with the MRI findings. RESULTS: A total of 42 atheromas (31.1%) had a fresh or recent intraplaque hemorrhage on the surgicopathological findings. A total of 38 (90.5%) of these patients showed high signal intensity halo around the carotid artery on the MIP images of TOF MR angiography. The high signal intensity halo sign, compared with the surgical and histopathological findings, demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 91%, 83%, 72%, and 95%, respectively, with a 95% confidence interval (CI) in the detection of an intraplaque hemorrhage. The multisequence approach suggested the presence of an intraplaque hemorrhage with a sensitivity, specificity, positive predictive value, and negative predictive value of 93%, 85%, 74%, and 96%, respectively, with a 95% CI. CONCLUSION: High signal intensity halo around the carotid artery on the MIP images of TOF MR angiography is useful in the noninvasive detection of a fresh or recent carotid intraplaque hemorrhage.

Endovascular treatment of posterior cerebral artery aneurysms using detachable coils.

INTRODUCTION: Aneurysms of the posterior cerebral artery (PCA) are rare, and most of the studies reported in the literature in which the endovascular approach was applied were carried out on a limited number of patients with PCA aneurysms. We retrospectively reviewed our cases of PCA aneurysms--at various locations and of differing shapes--that received endovascular treatment and evaluated the treatment outcome. METHODS: From January 1996 to December 2006, 13 patients (eight females and five males) with 17 PCA aneurysms (nine fusiform and eight saccular) were treated using the endovascular approach. The age of the patients ranged from 20 to 67 years, with a mean age of 44 years. Of the 13 patients, ten presented with intracranial hemorrhage, and one patient, with a large P2 aneurysm, presented with trigeminal neuralgia; the aneurysms were asymptomatic in the remaining two patients. RESULTS: All 13 patients were successfully treated, with only one procedure-related symptomatic complication. Seven patients were treated by occlusion of the aneurysm and parent artery together; five patients, by selective embolization of the aneurysm; one patient, by partial coiling. Although infarctions were found in two patients treated with selective embolization and in three patients treated with parent artery occlusion, only one patient with a ruptured P2 aneurysm treated with parent artery occlusion developed transient amnesia as an ischemic symptom. CONCLUSION: Posterior cerebral artery aneurysms can be treated safely with either occlusion of the aneurysm together with the PCA or with a selective coil embolization. Infarctions may occur after endovascular treatment, but they are rarely the cause of a disabling symptom.