Asymptomatic cystic changes in the brain of children after cranial irradiation: frequency, latency, and relationship to age.

INTRODUCTION: Although radiation therapy plays an important role in the management of children with brain tumors, radiation-induced brain damage sometimes occurs after radiation therapy. In some pediatric patients who had undergone cranial radiation therapy, we noticed cystic changes in the brain on follow-up MRI. The purpose of this study was to determine the frequency, latency, relationship with patient age, radiation dose, and serial change in the cystic changes in children after cranial irradiation. METHODS: We retrospectively studied MRI in 33 children who had undergone cranial irradiation for their primary brain tumors. Postirradiation cystic change in the brain on follow-up MRI was defined as a well-demarcated, oval-shaped, CSF-like signal intensity area, and no contrast enhancement. RESULTS: Of the 33 patients, 6 (18.2%) had one or more cystic lesions. The latency of the cystic changes ranged from 1.5 to 7 years (mean 2.6 years). Cystic changes were found in the subcortical, periventricular and other deep white matter and the basal ganglia. The size of the lesions ranged from 1 to 10 mm at their first appearance; eight cystic lesions increased in size. None the cystic lesions reduced in size or resolved with time and none required intervention. All patients with cystic changes had received irradiation when they were 6 years of age or younger. The cystic changes occurred within the radiation field in patients treated with a radiation dose of 36 Gy or more. CONCLUSION: Asymptomatic brain parenchymal cystic changes appear to occur in children who have undergone cranial irradiation at 6 years of age or younger.

Intracranial aneurysms at MR angiography: effect of computer-aided diagnosis on radiologists' detection performance.

PURPOSE: To retrospectively evaluate the effect of computer-aided detection (CAD) on radiologists' performance in detection of intracranial aneurysms with magnetic resonance (MR) angiography. MATERIALS AND METHODS: The institutional review board approved this study and did not require patient informed consent. Fifty maximum intensity projection MR angiograms in 50 patients were used for observer performance study. The group included 22 patients (age range, 43-86 years; mean, 60.2 years; 6 men and 16 women) with intracranial aneurysms and 28 patients (age range, 32-80 years; mean, 58.8 years; 10 men and 18 women) without aneurysms. The MR angiograms were obtained with three-dimensional time-of-flight 1.5-T MR imaging. Fifteen radiologists, including eight neuroradiologists and seven general radiologists, participated in the observer performance test. They interpreted the angiograms first without and then with the aid of the computer output by using an automated computerized scheme. The observers' performance without and with the computer output was evaluated with receiver operating characteristic analysis. RESULTS: For all 15 observers, average area under the receiver operating characteristic curve (A(z)) value for detection of aneurysms was increased significantly from 0.931 to 0.983 (P = .001) when they used the computer output. A(z) values for general radiologists and neuroradiologists increased from 0.894 to 0.983 (P = .022) and from 0.963 to 0.984 (P = .014), respectively. Improvement in the performance of general radiologists in terms of the A(z) value was much greater than that of neuroradiologists. Performance of general radiologists with CAD (A(z) = 0.983) slightly exceeded that of neuroradiologists without CAD (A(z) = 0.963) (P = .048). CONCLUSION: CAD improved neuroradiologists' and general radiologists' performance for detection of intracranial aneurysms with MR angiography; improvement was greater for general radiologists than it was for neuroradiologists.

Transthyretin-related familial amyloid polyneuropathy: evaluation of CSF enhancement on serial T1-weighted and fluid-attenuated inversion recovery images following intravenous contrast administration.

BACKGROUND AND PURPOSE: CSF enhancement on MR images after intravenous administration of gadolinium chelate, which mimics subarachnoid hemorrhage, has been reported. The purpose of this study was to determine whether CSF enhancement can be seen on serial MR images following administration of contrast material in patients with transthyretin-related familial amyloid polyneuropathy (FAP) and to assess other ancillary MR findings. METHODS: We serially studied T1-weighted and fluid-attenuated inversion recovery (FLAIR) images of the brain before, immediately after, and 3, 6, and 24 hours after contrast administration in 6 patients with genetically confirmed transthyretin-related FAP. By consensus, 2 radiologists assessed the presence, degree, and extent of enhancement of the CSF, leptomeninges, brain parenchyma, and other structures. Statistical analysis was performed to define the difference of the enhancement between the 2 MR imagings. RESULTS: In 3/6 patients with cysteine-for-tyrosine substitutions at position 114 (Tyr114Cys mutations), marked CSF enhancement was observed on the FLAIR images at 3 and 6 hours and on T1-weighted images at 3 hours after contrast administration. Although there was no significant difference between the 2 MR imagings, leptomeningeal enhancement for these 3 patients was evident only on FLAIR images. The labyrinth and vitreous body was also enhanced on postcontrast delayed MR images of these 3 patients. These enhancements were not observed in the other 3 patients with Val30Met mutation. In none of the 6 patients did images demonstrate parenchymal enhancement of the brain. CONCLUSION: In FAP patients with Tyr114Cys mutations, contrast material can leak into the CSF. This finding may depend on the subtype of FAP and be more evident with FLAIR images. The enhancement of the leptomeninges, labyrinth, and vitreous body was also seen in the patients.

Retrograde cortical and deep venous drainage in patients with intracranial dural arteriovenous fistulas: comparison of MR imaging and angiographic findings.

BACKGROUND AND PURPOSE: We assessed MR imaging, specifically contrast-enhanced three-dimensional (3D) magnetization-prepared rapid gradient-echo (MP-RAGE), in evaluating retrograde venous drainage in patients with intracranial dural arteriovenous fistulas (dAVFs) that may result in catastrophic venous infarction or hemorrhage. METHODS: Twenty-one patients with angiographically proved dAVFs underwent nonenhanced spin-echo (SE) and fast SE imaging, 3D fast imaging with steady-state precession, and enhanced SE and 3D MP-RAGE imaging. Retrograde venous drainage was categorized as cerebral cortical, deep cerebral, posterior fossa medullary, ophthalmic, or spinal venous. We assessed retrograde venous drainage and graded its severity. MR imaging and angiographic severities were correlated. Sensitivity, specificity, and accuracy were calculated to evaluate the diagnostic utility of each technique compared with conventional angiography. We retrospectively correlated angiograms and MR images. RESULTS: Enhanced 3D MP-RAGE and T1-weighted SE images had higher diagnostic accuracy higher than nonenhanced images, especially when retrograde drainage involved cerebral cortical, posterior fossa, and spinal veins. Correlation of severity for enhanced MP-RAGE images and enhanced T1-weighted images with angiograms was good to excellent and better than that with nonenhanced images. All sequences had low diagnostic accuracy when drainage was via deep cerebral veins. On retrospective review, 3D MP-RAGE images showed two thrombotic inferior petrosal sinuses. CONCLUSION: Enhanced MR images were superior to nonenhanced images in assessing retrograde venous drainage in intracranial dAVFs. Enhanced 3D MP-RAGE is superior to enhanced T1-weighted SE imaging for determining the route and severity of venous reflux because of its increased spatial resolution and ability to contiguously delineate the venous system.

Quantitative evaluation of measurement accuracy for three-dimensional angiography system using various phantoms.

PURPOSE: The purpose of this study was to evaluate the spatial resolution and accuracy of three-dimensional (3D) distance measurements performed with 3D angiography using various phantoms. MATERIALS AND METHODS: With a 3D angiography system, digital images with a 512 x 512 matrix were obtained with the C-arm sweep, which rotates at a speed of 30 degrees/second. A 3D comb phantom was designed to assess spatial resolution and artifacts at 3D angiography and consisted of six combs with different pitches: 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm. Frame rate, field of view (FOV) size, reconstruction matrix, and direction of the phantom were changed. In order to investigate the accuracy of 3D distance measurements, aneurysm phantoms and stenosis phantoms were used. Aneurysm phantoms simulated intracranial saccular aneurysms and parent arteries; 2-mm- or 4-mm-inner-diameter cylinder and five different spheres (diameter: 10, 7, 5, 3, 2 mm) were used. Stenosis phantoms were designed to simulate intracranial steno-occlusive diseases; the nonpulsatile phantoms were made of four cylinders (diameter: 3.0, 3.6, 4.0, 5.0 mm) that had areas of 50% and 75% stenosis. The dimensions of the spheres and cylinders were measured on magnified multiplanar reconstruction (MPR) images. RESULTS: The pitch of the 0.5 mm comb phantom was identified clearly on 3D images reconstructed with a frame rate of 30 frame/sec and 512(3) reconstruction mode. In any reconstruction matrixes and any angles of the phantom, the resolution and artifacts worsened when frame rates were decreased. With regard to the angle of the phantom to the axis of rotational angiography, spatial resolution and artifacts worsened with increase in angle. Spatial resolution and artifacts were better with a FOV of 7 x 7 inch than with one of 9 x 9 inch. All spheres on the aneurysm phantom were clearly demonstrated at any angle; measurement error of sphere size was 0.3 mm or less for 512(3) reconstruction. In 512(3) reconstruction, the error of percent stenosis was 3% or less except for a cylinder diameter of 3.0 mm and 5% for a cylinder diameter of 3.0 mm. CONCLUSION: Spatial resolution of the reconstructed 3D images in this system was 0.5 mm or less. Measurement error of sphere size was 0.3 mm or less when 512(3) reconstruction was used. When using proper imaging parameters and postprocessing methods, measurements of aneurysm size and percent stenosis on the reconstructed 3D angiograms were substantially reliable.

Pseudostenosis in vessels adjacent to intracranial aneurysms on volume-rendered 3D angiograms: a phantom study.

RATIONALE AND OBJECTIVE: Among artifacts on three-dimensional (3D) angiograms, pseudostenosis in vessels adjacent to intracranial aneurysms has not been described. By using a phantom, artifacts seen in vessels adjacent to intracranial aneurysms on volume-rendered 3D angiograms were assessed. MATERIALS AND METHODS: Using a 3D angiography system and a C-arm sweep, digital images were obtained with a 512 x 512 matrix. Rotation was 30 degrees /second, and frame rate was 30 frames/second. Phantom aneurysms were designed to simulate intracranial saccular aneurysms and their parent arteries. Phantoms, consisting of a cylinder (inner diameter, 2 or 4 mm) and spheres, 10, 7, 5, 3, or 2 mm in diameter, were placed at 0 degrees and 45 degrees to the axis of rotation. Two radiologists consensually recorded their findings regarding the presence and location of stenosis and its relationship to the angle of rotation. The maximum percentage of stenosis in the pseudostenosis area was measured on multiplanar reconstruction images by using a workstation computer. RESULTS: Pseudostenosis was observed in the cylinder adjacent to the sphere at both 0 degrees and 45 degrees angles; it was on a plane perpendicular to the axis of rotation. Pseudostenosis was most obvious with 10-mm spheres; it was not seen when spheres were 3 mm or less in diameter. The maximum percentage of stenosis of the pseudostenosis increased with sphere size. CONCLUSION: On volume-rendered 3D angiograms, pseudostenosis was seen in the cylinder adjacent to the sphere. The artifact lay on a plane perpendicular to the axis of rotation, and sphere size affected the artifact.

Evaluation of small hypothalamic hamartomas with 3D constructive interference in steady state (CISS) sequence.

Hypothalamic hamartomas are relatively rare, non-neoplastic congenital malformations. With conventional MR images alone, small hypothalamic hamartomas may be difficult to diagnose because of artifacts from cerebrospinal fluid. We present the usefulness of three-dimensional constructive interference in steady state sequence for evaluating small hypothalamic hamartomas in three pediatric patients.

Pineal cystic germinoma with syncytiotrophoblastic giant cells mimicking MR imaging findings of a pineal cyst.

We report a case of precocious puberty in a 4-year-old boy. Contrast-enhanced T1-weighted MR imaging suggested a pineal cyst with enhancement of the slightly thickened wall and focal wall irregularity. Three-dimensional constructive interference in a steady-state imaging revealed a focal lobulation and a nodule-like area in the lesion. The lesion mimicking a pineal cyst proved to be a germinoma with syncytiotrophoblastic giant cells, on the basis of biopsy and tumor marker results.

Familial amyloid polyneuropathy: hypertrophy of ligaments supporting the spinal cord.

We describe characteristic spinal MR findings of two cases of familial amyloid polyneuropathy (FAP). Both cases showed leptomeningeal enhancement on contrast-enhanced T1-weighted image. In addition, three-dimensional constructive interference in steady-state imaging demonstrated thickening of the ligaments, other connective tissues within the spinal canal, dura matter, and dorsal nerve roots. These findings in FAP are felt to represent amyloid deposition.

Intraarterial infusion chemotherapy for head and neck cancers: evaluation of tumor perfusion with intraarterial CT during carotid arteriography.

PURPOSE: To evaluate drug distribution in carcinomas of the head and neck region with CT during intraarterial contrast-material injection for superselective intraarterial infusion of anti-cancer agents, and to evaluate perfusion in the carcinomas with intraarterial dynamic CT, using a combined CT and angiography system. MATERIALS AND METHODS: Twenty-three consecutive patients underwent conventional angiography as well as intraarterial injection CT using a combined CT and angiography system. Contrast material enhancement on intraarterial CT images was evaluated qualitatively and quantitatively with the following parameters: enhanced pattern, delineation and extent of tumor, peak CT value, peak time, maximum inclination of wash-in and washout, and transfer index (k) using a Patlak plot method. After the feeding vessels had been identified by enhancement of the tumor on CT of the selected vessel, relatively low-dose cisplatin was injected through the microcatheter placed in each artery depending on tumor location. Histopathologic effects were evaluated after surgery and compared with CT findings. RESULTS: In the qualitative evaluation, tumors showed early, strong enhancement as well as rapid washout compared with the adjacent normal tissues, and dynamic CT was useful for evaluation of the extent of the tumor. When multiple feeders existed, the dose of cisplatin for each feeder could be determined by the percentage of tumor enhanced with CT on each vascular injection. The mean values of quantitative parameters, however, were not significantly different between the good and poor response groups. CONCLUSION: Intraarterial CT was useful for evaluation of the arterial supply and drug distribution of the tumor. However, quantitative data did not provide additional information for prediction of the treatment effect. This might indicate that the effectiveness of intraarterial chemotherapy is not directly related to the perfusion of head and neck cancers.

Pseudostenosis phenomenon at volume-rendered three-dimensional digital angiography of intracranial arteries: frequency, location, and effect on image evaluation.

PURPOSE: To assess the frequency, location, and effect on image interpretation of a pseudostenosis phenomenon at volume-rendered three-dimensional (3D) digital angiography for evaluation of intracranial arteries and to determine the physical characteristics of the phenomenon by using a phantom. MATERIALS AND METHODS: Results of a total of 68 volume-rendered 3D digital angiographic examinations in 56 patients with intracranial aneurysms were retrospectively evaluated in comparison with results of digital subtraction angiography regarding the appearance of a pseudostenosis phenomenon. The phenomenon was analyzed by two radiologists in consensus with regard to frequency, location, percentage stenosis, and angle between the axis of the vessel with pseudostenosis and the axis of rotational angiography. The phenomenon's effect on aneurysm evaluation was also analyzed. For assessing the physical properties of the phenomenon, a phantom study was performed with different lengths of tubing and different angles to the axis of rotational angiography. RESULTS: The pseudostenosis was observed at 23 (34%) of 68 3D digital angiographic examinations and in 53 (5%) of 1161 segments. The percentage stenosis ranged from 3% to 85% (mean, 18% +/- 16.2 [standard deviation]). The arterial segments with pseudostenosis included 15 (25%) of 61 C6 segments, 10 (16%) of 61 M1 segments, and six (10%) of 60 A1 segments. Angles between the two axes ranged from 86 degrees to 93 degrees (mean angle, 90 degrees +/- 1.6). Pseudostenosis affected delineation of the shape and size of two middle cerebral artery aneurysms. At phantom analysis, the phenomenon was most obvious at an angle of 90 degrees and with the longest phantom. CONCLUSION: The pseudostenosis phenomenon on volume-rendered 3D digital angiograms was relatively frequently observed in some segments of the intracranial arteries and affected the delineation of middle cerebral artery aneurysms. This phenomenon was associated with the angle to the axis of rotational angiography and the length of the vessel.

Clinical usefulness of unsubtracted 3D digital angiography compared with rotational digital angiography in the pretreatment evaluation of intracranial aneurysms.

BACKGROUND AND PURPOSE: Three-dimensional digital subtraction angiography (DSA) is useful as a supplement to 2D DSA in the pretreatment evaluation of intracranial aneurysms. However, the clinical efficacy of 3D digital angiography (DA) that is generated from unsubtracted rotational images has not been established. The purpose of this study was to assess whether 3D DA provides additional useful information to that of rotational DA in the preoperative evaluation of intracranial aneurysms. METHODS: This prospective study comprised 23 patients (age range, 37-83 years) with ruptured aneurysms who underwent angiography. Two radiologists independently evaluated the rotational DA images and the maximum intensity projection, shaded surface display, and volume-rendering 3D DA images, in combination with 2D DSA images. A four-point scoring system was used to evaluate aneurysm detection and delineation. Referring neurosurgeons were questioned as to whether the information obtained with 3D DA was useful for treatment decisions. RESULTS: Thirty aneurysms were confirmed by surgery or endovascular treatment. In detection and delineation of the 30 confirmed aneurysms, overall mean scores were highest with volume-rendering 3D DA and lowest with rotational DA. Compared with rotational DA, volume-rendering 3D DA demonstrated 27 additional findings in 14 (47%) of 30 aneurysms: detection of an aneurysm (n = 2), and delineation of aneurysm neck, shape, and relationship to adjacent arteries (n = 25). The information provided by 3D DA was useful for following treatment in five (22%) of 23 patients. CONCLUSION: In the preoperative evaluation of intracranial aneurysms, 3D DA can provide additional useful information to that of rotational DA.

Abnormal perfusion of the pituitary gland secondary to dural arteriovenous fistulas in the cavernous sinus: dynamic MR findings.

BACKGROUND AND PURPOSE: If venous congestion is the primary cause of pituitary gland enlargement in cases of dural arteriovenous fistulas (AVFs), other abnormal pituitary findings may be detectable on MR images. We sought to investigate the perfusion abnormality of the pituitary gland secondary to dural AVFs in the cavernous sinus and to clarify its clinical importance. METHODS: Nine consecutive patients (all female; age range, 50-77 years) with dural AVFs in the cavernous sinus underwent prospective MR examinations, including dynamic studies, before and after therapy. Their clinical signs and symptoms were recorded. Two radiologists visually evaluated the enhancement patterns of the anterior pituitary gland. Dynamic MR curves were obtained by locating regions of interest at the center and bilateral peripheral areas of the anterior pituitary gland on coronal images. MR images obtained in five healthy individuals served as controls. RESULTS: No patient had symptoms of hypopituitarism or other endocrine abnormalities. Asymmetric pituitary enhancement was found in five patients; the side with the dural AVF was less enhancing. This finding disappeared after therapy. Although asymmetric enhancement was not detected in the remaining four patients, statistical analysis showed significantly delayed enhancement of the pituitary gland in the patients compared with enhancement patterns in control subjects. After treatment, this delay improved significantly. The pituitary gland significantly decreased in size after treatment. CONCLUSION: Perfusion of the pituitary gland is impaired in patients with a dural AVF in the cavernous sinus. This finding is probably due to venous congestion of the pituitary gland caused by high pressure in the cavernous sinus; it is usually not related to pituitary dysfunction.