Detection of brain metastasis at 3T: comparison among SE, IR-FSE and 3D-GRE sequences

The objective of this study is to compare the detectability of brain metastases at 3T among three contrast-enhanced sequences, spin-echo (SE) sequence, inversion recovery fast SE (IR-FSE) sequence (both with section thickness of 6 mm), and three-dimensional fast spoiled gradient-echo (3D fast SPGR) sequence with 1.4 mm isotropic voxel. First, phantom studies were performed to quantify the contrast-enhancement ratio (CER) with three sequences. In 21 consecutive patients with brain metastases, axial images of three sequences at 3T were obtained after administration of gadoteridol. Two neuroradiologists assessed the detectability of brain metastases for the three sequences. In the phantom study, no evident difference in the CER was demonstrated among three sequences. Significantly more brain metastases were detected with 3D fast SPGR than with SE and IR-FSE (a total of 97 lesions with 3D fast SPGR vs. 64 with SE and 63 with IR-FSE). In particular, 3D fast SPGR was superior to the other two sequences in detection of the small lesions (<3 mm). At 3T, the contrast-enhanced 3D fast SPGR with 1.4 mm isotropic voxel is clinically more valuable for detecting small brain metastases than the SE and IR-FSE with section thickness of 6 mm.

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.

Effect of prophylactic hyperbaric oxygen treatment for radiation-induced brain injury after stereotactic radiosurgery of brain metastases

PURPOSE

The purpose of the present study was to evaluate the prophylactic effect of hyperbaric oxygen (HBO) therapy for radiation-induced brain injury in patients with brain metastasis treated with stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

The data of 78 patients presenting with 101 brain metastases treated with SRS between October 1994 and September 2003 were retrospectively analyzed. A total of 32 patients with 47 brain metastases were treated with prophylactic HBO (HBO group), which included all 21 patients who underwent subsequent or prior radiotherapy and 11 patients with common predictors of longer survival, such as inactive extracranial tumors and younger age. The other 46 patients with 54 brain metastases did not undergo HBO (non-HBO group). The radiation-induced brain injuries were divided into two categories, white matter injury (WMI) and radiation necrosis (RN), on the basis of imaging findings.

RESULTS

The radiation-induced brain injury occurred in 5 lesions (11%) in the HBO group (2 WMIs and 3 RNs) and in 11 (20%) in the non-HBO group (9 WMIs and 2 RNs). The WMI was less frequent for the HBO group than for the non-HBO group (p = 0.05), although multivariate analysis by logistic regression showed that WMI was not significantly correlated with HBO (p = 0.07). The 1-year actuarial probability of WMI was significantly better for the HBO group (2%) than for the non-HBO group (36%) (p < 0.05).

CONCLUSIONS

The present study showed a potential value of prophylactic HBO for the radiation-induced WMIs, which justifies further evaluation to confirm its definite benefit.

Effect of temporal subtraction technique on interpretation time and diagnostic accuracy of chest radiography

OBJECTIVE

Our purpose was to compare reviewing time and diagnostic accuracy in the interpretation of radiographs without and with subtraction images and to examine whether this temporal subtraction technique can contribute to improving radiologists' performance.

MATERIALS AND METHODS

Thirty cases with newly developed chest abnormalities on chest radiographs and 90 negative cases were selected. All chest radiographs were obtained with a computed radiography system. For the 90 negative cases, subtraction images were classified into two groups: 33 clean images without misregistration artifacts and 57 images with some misregistration artifacts. Eight radiologists (four board-certified radiologists and four radiology residents) participated in observer tests and interpreted the original radiographs without and with subtraction images using an independent test method. The reviewing time for each radiologist was recorded in each case. The observers' performance was evaluated by use of receiver operating characteristic (ROC) analysis.

RESULTS

When subtraction images were available, the mean reviewing time per case was reduced significantly from 13.6 to 10.8 seconds for the cases with newly developed abnormalities (p < 0.001) and from 29.8 to 14.1 seconds for negative cases (p < 0.001). The reduction in the mean reviewing time with subtraction images was greater for clean images than for images with artifacts (17.7 vs 14.5 seconds, p < 0.001). The average mean area under the ROC curve value increased significantly from 0.942 without subtraction images to 0.988 with subtraction images (p = 0.025). There were significant differences in the sensitivity (0.963 with and 0.888 without the subtraction images) and the specificity (0.976 with and 0.899 without the subtraction images) (p < 0.001).

CONCLUSION

The temporal subtraction technique can reduce reviewing time and also improve diagnostic accuracy in the interpretation of chest radiographs.

Targeted intra-arterial carboplatin chemoradiotherapy and tegafur/uracil for oral and oropharyngeal cancer

The aim of this study was to evaluate the usefulness of targeted intra-arterial carboplatin chemoradiotherapy in allowing less invasive surgery for patients with oral and oropharyngeal squamous cell carcinoma. Twenty patients with previously untreated squamous cell carcinoma of the oral cavity and oropharynx (T4; 8, T2; 12 patients) were treated with targeted transfemoral intra-arterial carboplatin infusion with concurrent hyperfractionated radiotherapy and the administration of tegafur/uracil (UFT). Of 20 patients, 15 underwent surgery after completion of one course of targeted chemoradiotherapy, and five were given another course or radiotherapy only. Eighteen (90%) of 20 patients had a clinically complete response at the primary site and two (10%) had a partial response. Of the 15 patients who underwent tumor resection, 11 (73%) showed histopathological disappearance of cancer cells at the primary site. Sixteen (80 %) of 20 tumors were controlled at the primary site within a mean follow-up of 30 months. Adverse effects were relatively mild. Targeted intra-arterial chemoradiotherapy caused a down-staging of tumors and facilitated the use of less invasive surgery in patients with squamous cell carcinoma of the oral cavity and oropharynx as a result of its favorable anti-tumor effect.

Superselective arterial infusion chemotherapy for squamous cell carcinomas of the oral cavity: histopathologic effects on metastatic neck lymph nodes

We have performed superselective intra-arterial infusion chemotherapy (SIC) on carcinomas of the oral cavity according to a protocol in which the distribution of the drug was evaluated by the use of a combined CT and angiography system, and the chemotherapy was combined with medium-dose conformal radiation therapy (CRT). The purpose of this study was to evaluate the pathological effect of this treatment on the metastatic neck lymph nodes (LNs). Twenty consecutive patients who had metastatic neck LNs from squamous cell carcinomas of the mouth and who underwent both SIC and CRT were included in this study, in which a total of 22 LNs were evaluated. A microcatheter was placed in the appropriate feeding artery of the tumor, such as the internal maxillary artery, facial artery, lingual artery and external carotid artery (ECA), and cisplatin (50 mg/body) was infused twice through a microcatheter. The CRT was administered with a dual-energy (4 and 10 MV) linear accelerator. The total and daily doses delivered were 30 and 2.0 Gy, respectively. Intra-arterial infusion to the LNs was divided into two groups: superselective infusion (mainly to the submandibular LNs via the facial artery, n = 10) and nonsuperselective infusion via the ECA (n = 12). The distribution of cisplatin into the LNs was confirmed by slow-infusion CT. Histopathologic effects on the LNs were evaluated on the specimens obtained during the operation and classified into five grades (0: no or minimal response: I: disappearance of less than three quarters of the tumor cells: II: disappearance of more than three quarters of the tumor cells: III: disappearance of viable tumor cells with a small amount of residual nonviable tumor cells: IV: complete disappearance of all viable and nonviable tumor cells). Grade 0 or 1 was defined as poor response and Grade II or more as good response. Twenty-three LNs from nine patients without CRT and SIC were served as control. In the superselective infusion group, all 10 LNs showed good response (response rate, 100%: grade II = 4, grade III = 3, grade IV = 3). In the non-superselective group, however, 6 of 12 LNs showed poor response (response rate, 50%: grade 0 = 2, grade I = 4, grade II = 2, grade III = 2, grade IV = 2). All 23 control LNs with no treatment showed grade 0 response. Superselective infusion seems necessary to obtain good histopathologic effects on the metastatic LNs. SIC combined with CRT can be applied to the metastatic LNs.

Correlation between numeric gadolinium-enhanced dynamic MRI ratios and prognostic factors and histologic type of breast carcinoma

OBJECTIVE

The purpose of this study was to assess the usefulness of numeric ratios from dynamic contrast-enhanced MRI in predicting histologic type of breast carcinoma and three histologic prognostic factors for invasive ductal carcinoma.

MATERIALS AND METHODS

A total of 104 patients with breast carcinoma were included in the study. Dynamic contrast-enhanced MR images were obtained every 30 seconds during the first 4.5 minutes after administration of contrast material, and peripheral contrast enhancement ratio and central contrast enhancement ratio were calculated in the early phase (1 minute after contract injection) and in the delayed phase (4 minutes after injection). Four contrast enhancement ratios were used for quantitative analysis of the following numeric ratios: early peripheral/early central, delayed peripheral/delayed central, delayed peripheral/early peripheral, and delayed central/early central. The four ratios were compared with histologic type. For invasive ductal carcinoma, the ratios were then compared with modified Scarff-Bloom-Richardson histologic grade, microvessel density, and fibrotic focus.

RESULTS

Mucinous carcinoma had significantly higher mean early peripheral/early central and delayed central/early central ratios than other types of tumors (p< 0.0001). For invasive ductal carcinoma, the mean early peripheral/early central ratio was significantly lower for modified Scarff-Bloom-Richardson grade 1 tumors than for grades 2 and 3 tumors (p < 0.0001). Early peripheral/early central ratio had a significant correlation with the ratio of peripheral to central mean microvessel density (p < 0.0001). There was also a significant difference in early peripheral/early central ratio (p < 0.0001) between tumors with a fibrotic focus and those without a fibrotic focus.

CONCLUSION

Numeric ratios obtained on gadolinium-enhanced dynamic MRI of the breast may be useful in predicting histologic type of breast carcinoma and three histologic prognostic factors for invasive ductal carcinoma: modified Scarff-Bloom-Richardson grade, microvessel density, and fibrotic focus.

An unusual case of split cord malformation

We present a variant of a split cord malformation with coexisting segmental spinal dysgenesis. CT myelography showed the left hemicord with a small remnant of subarachnoid space running through an intravertebral cleft in a spine anomaly. The left hemicord had no apparent intradual connection to the upper cord on any radiologic examination, though functional electrical stimulation studies revealed an intact efferent pathway that connected the left hemicord to the main spinal cord.

Diffusion-weighted imaging of metastatic brain tumors: comparison with histologic type and tumor cellularity

BACKGROUND AND PURPOSE

On diffusion-weighted imaging (DWI), metastatic tumors of the brain may exhibit different signal intensities (SI) depending on their histology and cellularity. The purpose of our study was to verify the hypotheses (1) that SI on DWI predict the histology of metastases and (2) that apparent diffusion coefficient (ADC) values reflect tumor cellularity.

MATERIALS AND METHODS

We assessed conventional MR images, DWI, and ADC maps of 26 metastatic brain lesions from 26 patients, 13 of whom underwent surgery after the MR examination. Two radiologists performed qualitative assessment by consensus of the SI on DWI in areas corresponding to their enhancing portions. We measured the contrast-to-noise ratio (CNR) on T2-weighted images and normalized ADC (nADC) values, and compared them with tumor cellularity.

RESULTS

The mean SI on DWI and the CNR on T2-weighted images were significantly lower in well differentiated than in poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. The mean nADC value was significantly higher in well differentiated than poorly differentiated adenocarcinomas and lesions other than adenocarcinoma. All 3 small-cell carcinomas and 1 large-cell neuroendocrine carcinoma exhibited high SI on DWI. The nADC value showed a significant inverse correlation with tumor cellularity. There was no significant correlation between the CNR and tumor cellularity.

CONCLUSION

The SI on DWI may predict the histology of metastases; well differentiated adenocarcinomas tended to be hypointense, and small- and large-cell neuroendocrine carcinomas showed hyperintensity. Their ADC values reflect tumor cellularity.

Usefulness of measurement of the temporal stem on magnetic resonance imaging in the diagnosis of frontotemporal dementia

PURPOSE

To investigate whether measurements of brain structures on routine magnetic resonance (MR) images can be used to distinguish between normal subjects and patients with frontotemporal dementia (FTD) or Alzheimer's disease (AD).

MATERIAL AND METHODS

MRI studies were performed on 30 patients with dementia (FTD, n = 15; AD, n = 15) and 15 age-matched controls. Width measurements, obtained at the corpus callosum, the cingulate gyri, the hippocampi, and the temporal stem of the anterior temporal lobes, were compared among FTD and AD patients and control subjects on oblique-coronal T2-weighted images.

RESULTS

The width of the temporal stem was significantly narrower in FTD than in AD patients and control subjects (6.3 +/- 1.3 mm, 7.8 +/- 1.1 mm, and 8.2 +/- 0.9 mm, respectively) (P < 0.05), although there was some overlapping between AD and FTD patients. All patients whose temporal stem width was < 6 mm had FTD. While the width of the corpus callosum, cingulate gyri, and hippocampi was significantly narrower in patients with AD and FTD than in the controls, there was no significant difference between the AD and FTD patients.

CONCLUSION

The width of the temporal stem was significantly narrower in patients with FTD than in those with AD and controls. The described measurements can easily be obtained and may be useful for the diagnosis of FTD.

Cytogenetic analysis of myxoid liposarcoma and myxofibrosarcoma by array-based comparative genomic hybridisation

AIM

To investigate overall chromosomal alterations using array-based comparative genomic hybridisation (CGH) of myxoid liposarcomas (MLSs) and myxofibrosarcomas (MFSs).

MATERIALS AND METHODS

Genomic DNA extracted from fresh-frozen tumour tissues was labelled with fluorochromes and then hybridised on to an array consisting of 1440 bacterial artificial chromosome clones representing regions throughout the entire human genome important in cytogenetics and oncology.

RESULTS

DNA copy number aberrations (CNAs) were found in all the 8 MFSs, but no alterations were found in 7 (70%) of 10 MLSs. In MFSs, the most frequent CNAs were gains at 7p21.1-p22.1 and 12q15-q21.1 and a loss at 13q14.3-q34. The second most frequent CNAs were gains at 7q33-q35, 9q22.31-q22.33, 12p13.32-pter, 17q22-q23, Xp11.2 and Xq12 and losses at 10p13-p14, 10q25, 11p11-p14, 11q23.3-q25, 20p11-p12 and 21q22.13-q22.2, which were detected in 38% of the MFSs examined. In MLSs, only a few CNAs were found in two sarcomas with gains at 8p21.2-p23.3, 8q11.22-q12.2 and 8q23.1-q24.3, and in one with gains at 5p13.2-p14.3 and 5q11.2-5q35.2 and a loss at 21q22.2-qter.

CONCLUSIONS

MFS has more frequent and diverse CNAs than MLS, which reinforces the hypothesis that MFS is genetically different from MLS. Out-array CGH analysis may also provide several entry points for the identification of candidate genes associated with oncogenesis and progression in MFS.

Radiotherapy with 8 MHz radiofrequency-capacitive regional hyperthermia for pain relief of unresectable and recurrent colorectal cancer

PURPOSE

The purpose of this study was to assess the pain relief in patients with unresectable and recurrent colorectal cancer treated with radiation plus 8 MHz radiofrequency-capacitive regional hyperthermia and to identify predictors of the good outcome.

METHODS

Between February 1986-May 2003, 41 patients with primarily unresectable and recurrent colorectal cancer that caused pain were treated with thermoradiotherapy at the hospital and retrospectively analysed. Radiotherapy was administered with a mean total radiation dose of 56 Gy. Hyperthermia was usually applied within 30 min after radiotherapy once or twice a week. For cooling of the skin surface, the overlay boluses were applied in addition to regular boluses. The external cooling unit has been used to reinforce the cooling ability of the overlay bolus and achieve strong surface cooling to reduce the preferential heating of the subcutaneous fat tissue and treat with more RF-output in 17 patients since January 1997.

RESULTS

Pain relief was obtained in 83% of the patients. Multi-variate analysis by logistic regression to evaluate the effects of certain factors on pain relief (complete response + good response) was strongly correlated with the presence of radiating pain to leg(s) (p < 0.05). The median follow-up was 18 months. The median duration of pain relief was 7.0 months. For the 27 patients in whom the tumour temperature was estimated, the median duration of pain relief was 14.6 months for the patients with a mean average tumour temperature of > 42.5 degrees C and 5.7 months for those of < 42.5 degrees C (p < 0.05). In the 18 patients with radiating pain to leg(s), use of strong superficial cooling and the higher numbers of hyperthermia treatments were better prognostic factors for the duration of pain relief (p < 0.01 and p < 0.05, respectively).

CONCLUSIONS

Radiotherapy with 8 MHz radiofrequency-capacitive regional hyperthermia provided an efficient, effective means on pain relief of treating unresectable and recurrent colorectal cancer. The duration of pain relief can be prolonged, if an adequate heating is achieved, especially in the patients with radiating pain to the leg(s).

Intracranial 2D and 3D DSA with flat panel detector of the direct conversion type: initial experience

The purpose of this study was to compare the image quality of two-dimensional (2D) digital subtraction angiography (DSA) between a flat panel detector (FPD) of the direct conversion type with low radiation dose and a conventional image intensifier (I.I.)-TV system, and to assess 3D DSA with the FPD system in the depiction of intracranial vessels. Fifteen consecutive patients (five men, ten women; age range: 18-82 years; mean age: 55.5 years) were prospectively included in this study. All patients underwent 2D DSA with both the FPD and I.I.-TV system in one projection. The radiation doses during angiography were evaluated using a phantom. The 3D DSA images were created from the rotational DSA data with the FPD system. Two blinded radiologists independently evaluated 2D DSA with the FPD system and I.I.-TV system using a 5-point assessment scale (excellent to not visible) to assess the depiction of intracranial vessels. MIP and volume rendering (VR) images of 3D DSA with the FPD system were also evaluated using a 5-point scale (excellent to not visible). DSA and fluoroscopy dose measurements with the phantom showed a dose reduction of approximately 85% and 9% with the FPD system compared with the I.I.-TV system, respectively. For 2D DSA, the FPD system was significantly superior to the I.I.-TV system with respect to the visibility of the peripheral and perforating vessels (p<0.05). The peripheral and perforating vessels were also sufficiently visualized on MIP images of 3D DSA in all 15 cases. Our FPD system was found to be superior to the I.I.-TV system in visualizing small intracranial vessels combined with a significant reduction of radiation dose, and was able to create high-quality 3D DSA images on which high spatial resolution allowed precise visualization of small vessels such as perforating ones.

Computerized detection of intracranial aneurysms for three-dimensional MR angiography: feature extraction of small protrusions based on a shape-based difference image technique

We have improved a computerized scheme for the detection of intracranial aneurysms for three-dimensional (3-D) magnetic resonance angiography (MRA) by the use of image features of small protrusions extracted based on a shape-based difference image (SBDI) technique. Initial candidates were identified by use of a multiple gray-level thresholding technique in dot enhanced images, and by finding short branches in skeleton images. Image features related to aneurysms were determined based on candidate regions segmented by use of a region growing technique. For extracting additional features on small protrusions or small aneurysms, we have developed an SBDI technique, which was based on the shape-based difference between an original segmented vessel and a vessel with suppressed local change in thickness. The SBDI technique was useful for obtaining local changes in vessel thickness, i.e., SBD regions, which could be small aneurysms in the case of true positives, but thin or very small regions in the case of false positives. Many false positives were removed by means of rule-based schemes and linear discriminant analysis on various 3-D localized image features, including SBDI features. We tested the computerized scheme on 53 cases with 61 aneurysms and 62 nonaneurysm cases based on a leave-one-out-by-patient test method. As a result, false positives per patient decreased from 5.8 to 3.8, while a high sensitivity of 97% was maintained by use of the SBDI technique, in which SBDI features were effective for removing some false positives. The computer-aided diagnostic (CAD) scheme may be robust and useful in assisting radiologists in the detection of intracranial aneurysms for MRA.

Signal intensity of the normal pontine tegmentum on T2-weighted MR imaging

On T2-weighted MR images, the pontine tegmentum frequently shows a signal of high intensity in neurologically healthy individuals. We examined whether the signal intensity of the pontine tegmentum normally differs from that of the pontine base. We evaluated the signal intensity of the pontine tegmentum and pontine base on T2-weighted images from 38 neurologically healthy subjects. The subjects included 29 adults (16 males and 13 females, age range 23-48 years, mean age 39.5 years) and 9 children (4 boys and 5 girls (age range 4-9 years mean age 6.5 years). We compared the contrast-to-noise ratio (CNR) between the tegmentum and the base in the upper pons, midpons and lower pons, and evaluated the signal intensity ratio of the tegmentum to the base. The CNR was significantly higher for the tegmentum than the base at each level of the pons (P<0.0001), and the signal intensity ratio of the tegmentum to the base in the upper pons was significantly higher in children than in adults (P<0.005). On T2-weighted images, a high signal intensity of the pontine tegmentum is frequently seen in neurologically healthy subjects. This finding should not be considered abnormal, particularly in children.

Evaluation of drainage patterns of the major anastomotic veins on the lateral surface of the cerebrum using three-dimensional contrast-enhanced MP-RAGE sequence

BACKGROUND AND PURPOSE

Three-dimensional (3D) contrast-enhanced magnetization-prepared rapid gradient-echo (MP-RAGE) sequence has been reported useful for evaluation of the intracranial venous structures. The purpose of this study is to assess the patterns of the major anastomotic veins on the lateral surface of the cerebrum using MP-RAGE sequence.

METHODS

MP-RAGE images in consecutive 100 patients (200 sides) were reviewed by two neuroradiologists in consensus to evaluate drainage patterns of the superficial middle cerebral vein (SMCV), the vein of Labbe, and the Trolard vein.

RESULTS

MP-RAGE images clearly depicted the major anastomotic veins and their draining vessel. The dominant vein was the Trolard vein in 12%, the vein of Labbe in 36%, SMCV in 38%, and all three veins in 14%. The vein of Labbe was entered the transverse sinus in 80% and superior petrosal sinus in 4%. Undeveloped type of the vein of Labbe was seen in 16%. The SMCVs were entered the sphenoparietal sinus in 57%, the cavernous sinus in 19%, and the emissary vein in 5%. Basal type of the SMCVs was seen in 3% and undeveloped type in 16%. It was difficult to differentiate the Trolard vein from other cortical veins, if it was not dominant. In the most cases with the dominant Trolard vein, it located at the level of the post central vein.

CONCLUSION

With MP-RAGE sequence, it is easy to identify the variation of the major anastomotic veins. Such information may be helpful to reduce the risk of damage on these important veins at surgery.

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.

Evaluation of vascular supply with angio-computed tomography during intra-arterial chemotherapy for brain tumors

We report the utility of a combined angiography and computed tomography (angio-CT) system in assessing drug distribution to the tumor during intra-arterial chemotherapy for metastatic brain tumors in a 65-year-old man. Although digital subtraction angiography did not clearly show tumor perfusion in two cerebellar tumors, angio-CT provided definite tumor perfusion in the complicated vascular territory, and anticancer agents were infused based on its findings. To our knowledge, however, this application for intra-arterial chemotherapy of brain tumors has not been previously described.

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.

Diffusion-weighted imaging of radiation-induced brain injury for differentiation from tumor recurrence

BACKGROUND AND PURPOSE

Differentiation between tumor recurrence and treatment-related brain injury is often difficult with conventional MRI. We hypothesized that the diffusion-weighted imaging (DWI) could help differentiate these 2 conditions, because water diffusion may be greater for necrotic tissues in the treatment-related brain injury than for tumor tissues in recurrence. Our aim was to analyze whether DWI findings of recurrent tumor are distinct from those of radiation necrosis.

METHODS

Seventeen patients were examined prospectively. Two readers assessed the images by consensus for homogeneity and signal intensity of the lesions. Five regions of interest were drawn within the lesions on trace DWI images and apparent diffusion coefficient (ADC) maps. The minimal, maximal, and mean values of each lesion were compared between the 2 groups. Findings in 12 of 17 patients were verified histologically by surgery or biopsy; the diagnoses in the remaining 5 patients were made on the basis of follow-up MRI findings and clinical follow-up.

RESULTS

There were a total of 20 lesions; 12 lesions were due to radiation necrosis and 8 lesions to tumor recurrence. In the radiation necrosis group, 8 lesions had marked hypointensity. In the recurrence group, however, no marked hypointensity was seen. The maximal ADC values within each lesion were significantly smaller for the recurrence group than for the necrosis group (P = .039).

CONCLUSION

Radiation necrosis usually showed heterogeneity on DWI images and often included spotty, marked hypointensity. Significant difference was found in the maximal ADC values between radiation necrosis and tumor recurrence. DWI was useful in differentiating recurrent neoplasm from radiation necrosis.

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.

Spinal MR findings in continuous epidural analgesia without infection

BACKGROUND AND PURPOSE

Spinal epidural abscesses are major complications of epidural anesthesia, and their MR features have been reported. In patients receiving continuous infusion via an epidural catheter, MR findings may mimic those of spinal epidural abscess in the absence of infection. The purpose of this study was to assess the spinal MR findings associated with continuous epidural anesthesia.

METHODS

Spinal MR findings in five consecutive patients receiving continuous epidural anesthesia were retrospectively evaluated. Axial and sagittal T1- and T2-weighted spin-echo and contrast-enhanced fat-suppressed T1-weighted spin-echo images were obtained. Infection was ruled out on microbiologic analysis three patients and on follow-up in two. Each lesion was evaluated for its MR signal intensity, location, extent, delineation, and enhancement pattern. In three patients, follow-up MR imaging was performed within 5-150 days, and the images were compared.

RESULTS

Posterior epidural lesions were identified in all five patients. The lesions were isointense to hypointense relative to the spinal cord on T1-weighted images, isointense relative to CSF on T2-weighted images, and well enhanced on enhanced T1-weighted images. The anomalous enhancement involved two to seven vertebral bodies. In one patient, the enhanced lesion slightly compressed the spinal cord. On follow-up MR imaging, the epidural lesions decreased in two patients and did not change in one.

CONCLUSION

Continuous epidural anesthesia can result in MR findings similar to those of epidural abscess, even in the absence of infection.

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.