Repeatability of Automated Image Segmentation with BraTumIA in Patients with Recurrent Glioblastoma.

BACKGROUND AND PURPOSE: Despite high interest in machine-learning algorithms for automated segmentation of MRIs of patients with brain tumors, there are few reports on the variability of segmentation results. The purpose of this study was to obtain benchmark measures of repeatability for a widely accessible software program, BraTumIA (Versions 1.2 and 2.0), which uses a machine-learning algorithm to segment tumor features on contrast-enhanced brain MR imaging. MATERIALS AND METHODS: Automatic segmentation of enhancing tumor, tumor edema, nonenhancing tumor, and necrosis was performed on repeat MR imaging scans obtained approximately 2 days apart in 20 patients with recurrent glioblastoma. Measures of repeatability and spatial overlap, including repeatability and Dice coefficients, are reported. RESULTS: Larger volumes of enhancing tumor were obtained on later compared with earlier scans (mean, 26.3 versus 24.2 mL for BraTumIA 1.2; P < .05; and 24.9 versus 22.9 mL for BraTumIA 2.0, P < .01). In terms of percentage change, repeatability coefficients ranged from 31% to 46% for enhancing tumor and edema components and from 87% to 116% for nonenhancing tumor and necrosis. Dice coefficients were highest (>0.7) for enhancing tumor and edema components, intermediate for necrosis, and lowest for nonenhancing tumor and did not differ between software versions. Enhancing tumor and tumor edema were smaller, and necrotic tumor larger using BraTumIA 2.0 rather than 1.2. CONCLUSIONS: Repeatability and overlap metrics varied by segmentation type, with better performance for segmentations of enhancing tumor and tumor edema compared with other components. Incomplete washout of gadolinium contrast agents could account for increasing enhancing tumor volumes on later scans.

Quantitative Delta T1 (dT1) as a Replacement for Adjudicated Central Reader Analysis of Contrast-Enhancing Tumor Burden: A Subanalysis of the American College of Radiology Imaging Network 6677/Radiation Therapy Oncology Group 0625 Multicenter Brain Tumor Trial.

BACKGROUND AND PURPOSE: Brain tumor clinical trials requiring solid tumor assessment typically rely on the 2D manual delineation of enhancing tumors by ≥2 expert readers, a time-consuming step with poor interreader agreement. As a solution, we developed quantitative dT1 maps for the delineation of enhancing lesions. This retrospective analysis compares dT1 with 2D manual delineation of enhancing tumors acquired at 2 time points during the post therapeutic surveillance period of the American College of Radiology Imaging Network 6677/Radiation Therapy Oncology Group 0625 (ACRIN 6677/RTOG 0625) clinical trial. MATERIALS AND METHODS: Patients enrolled in ACRIN 6677/RTOG 0625, a multicenter, randomized Phase II trial of bevacizumab in recurrent glioblastoma, underwent standard MR imaging before and after treatment initiation. For 123 patients from 23 institutions, both 2D manual delineation of enhancing tumors and dT1 datasets were evaluable at weeks 8 (n = 74) and 16 (n = 57). Using dT1, we assessed the radiologic response and progression at each time point. Percentage agreement with adjudicated 2D manual delineation of enhancing tumor reads and association between progression status and overall survival were determined. RESULTS: For identification of progression, dT1 and adjudicated 2D manual delineation of enhancing tumor reads were in perfect agreement at week 8, with 73.7% agreement at week 16. Both methods showed significant differences in overall survival at each time point. When nonprogressors were further divided into responders versus nonresponders/nonprogressors, the agreement decreased to 70.3% and 52.6%, yet dT1 showed a significant difference in overall survival at week 8 (P = .01), suggesting that dT1 may provide greater sensitivity for stratifying subpopulations. CONCLUSIONS: This study shows that dT1 can predict early progression comparable with the standard method but offers the potential for substantial time and cost savings for clinical trials.

Repeatability of Standardized and Normalized Relative CBV in Patients with Newly Diagnosed Glioblastoma.

BACKGROUND AND PURPOSE: For more widespread clinical use advanced imaging methods such as relative cerebral blood volume must be both accurate and repeatable. The aim of this study was to determine the repeatability of relative CBV measurements in newly diagnosed glioblastoma multiforme by using several of the most commonly published estimation techniques. MATERIALS AND METHODS: The relative CBV estimates were calculated from dynamic susceptibility contrast MR imaging in double-baseline examinations for 33 patients with treatment-naïve and pathologically proved glioblastoma multiforme (men = 20; mean age = 55 years). Normalized and standardized relative CBV were calculated by using 6 common postprocessing methods. The repeatability of both normalized and standardized relative CBV, in both tumor and contralateral brain, was examined for each method with metrics of repeatability, including the repeatability coefficient and within-subject coefficient of variation. The minimum sample size required to detect a parameter change of 10% or 20% was also determined for both normalized relative CBV and standardized relative CBV for each estimation method. RESULTS: When ordered by the repeatability coefficient, methods using postprocessing leakage correction and ΔR2*(t) techniques offered superior repeatability. Across processing techniques, the standardized relative CBV repeatability in normal-appearing brain was comparable with that in tumor (P = .31), yet inferior in tumor for normalized relative CBV (P = .03). On the basis of the within-subject coefficient of variation, tumor standardized relative CBV estimates were less variable (13%-20%) than normalized relative CBV estimates (24%-67%). The minimum number of participants needed to detect a change of 10% or 20% is 118-643 or 30-161 for normalized relative CBV and 109-215 or 28-54 for standardized relative CBV. CONCLUSIONS: The ΔR2* estimation methods that incorporate leakage correction offer the best repeatability for relative CBV, with standardized relative CBV being less variable and requiring fewer participants to detect a change compared with normalized relative CBV.

A change in the apparent diffusion coefficient after treatment with bevacizumab is associated with decreased survival in patients with recurrent glioblastoma multiforme.

OBJECTIVES: The aim of this study was to determine the prognostic significance of changes in parameters derived from diffusion tensor imaging (DTI) that occur in response to treatment with bevacizumab and irinotecan in patients with recurrent glioblastoma multiforme. METHODS: 15 patients with recurrent glioblastoma multiforme underwent serial 1.5 T MRI. Axial single-shot echo planar DTI was obtained on scans performed 3 days and 1 day prior to and 6 weeks after initiation of therapy with bevacizumab and irinotecan. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were registered to whole brain contrast-enhanced three-dimensional (3D) spoiled gradient recalled and 3D fluid attenuation inversion recovery (FLAIR) image volumes. Anatomic image volumes were segmented to isolate regions of interest defined by tumour-related enhancement (TRE) and FLAIR signal abnormality (FSA). Mean ADC and mean FA were calculated for each region. A Bland-Altman repeatability coefficient was also calculated for each parameter based on the two pre-treatment studies. A patient was considered to have a change in FA or ADC after therapy if the difference between the pre- and post-treatment values was greater than the repeatability coefficient for that parameter. Survival was compared using a Cox proportional hazard model. RESULTS: DTI detected a change in ADC within FSA after therapy in nine patients (five in whom ADC was increased; four in whom it was decreased). Patients with a change in ADC within FSA had significantly shorter overall survival (p=0.032) and progression free survival (p=0.046) than those with no change. CONCLUSION: In patients with recurrent glioblastoma multiforme treated with bevacizumab and irinotecan, a change in ADC after therapy in FSA is associated with decreased survival.

Prognostic significance of parameters derived from co-registered 18F-fluorodeoxyglucose PET and contrast-enhanced MRI in patients with high-grade glioma.

OBJECTIVE: The aim of this study was to determine the prognostic significance of the volume and intensity of abnormal (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) accumulation within areas of contrast enhancement on post-therapeutic volumetric MRI. METHODS: A total of 10 patients with Grade III or IV glioma were treated with resection followed by intracavitary radiation therapy with (131)I-labelled antitenascin monoclonal antibody. Patients underwent serial FDG-PET and 1.5 T MR imaging. For each patient, MR and FDG-PET image volumes at each time point were aligned using a rigid-body normalised mutual information algorithm. Contrast-enhancing regions of interest (ROIs) were defined using a semi-automated k-means clustering technique. Activity within the ROI on the co-registered PET scan was calculated as a ratio (mean activity ratio; MAR) to activity in contralateral normal-appearing white matter (NAWM). The PET lesion was defined as the portion of the ROI associated with activity greater than two standard deviations above the mean in NAWM. Survival was assessed using the logrank test. RESULTS: Larger contrast-enhancing ROIs were strongly associated with an increased MAR (r = 0.51; p<0.002). Enhancing lesions with an MAR >1.2 were associated with decreased survival (p<0.016). In nine patients who died, the MAR on PET correlated inversely with survival duration (r = -0.43; p<0.01), whereas PET lesion volume did not. CONCLUSION: Following intracavitary radiation therapy, the development of contrast-enhancing lesions that are associated with high mean FDG-PET accumulation suggests poor prognosis.

Ruptured maxillary retention cyst: cause of unilateral rhinorrhea after trauma.

This study describes a case of a patient with traumatic rupture of a maxillary sinus retention cyst, which had an interesting clinical presentation of unilateral rhinorrhea, mimicking a CSF leak. The diagnosis was made fortuitously by comparison of a posttraumatic CT brain examination with a CT sinus study performed 1 day earlier.

Serial MR imaging of pineal cysts: implications for natural history and follow-up.

OBJECTIVE: The purpose of this study was to examine the frequency of change in size of pineal cysts on serial MR studies. MATERIALS AND METHODS: Thirty-two patients (19 females, 13 males) with a diagnosis of pineal cyst at any time who underwent brain MR imaging more than once in a period of at least 6 months were identified by computerized search of radiology reports. Four patients underwent MR imaging to follow up pineal cysts, whereas the remaining patients were imaged for a variety of indications, including intracerebral neoplasms. Measurements of maximal cyst dimension on both initial and latest follow-up studies were obtained in all patients, and cyst volumes were calculated in 23 patients. RESULTS: Length of follow-up ranged from 6 months to 9 years. All cysts were considered incidental and none were treated. Maximal cyst dimensions ranged from 0.5 to 2.2 cm. On average, there was no significant change in cyst volume. The maximal dimension of the cyst did not change in 24 (75%) of 32 patients. Two cysts resolved completely on follow-up, three cysts decreased by 2-4 mm, two cysts enlarged by 2-3 mm, and one cyst formed and grew to 1.2 cm. CONCLUSION: Whereas the size of pineal cysts as a whole remained unchanged on serial MR studies, cysts may either form or involute in individual patients. Small increases in cyst size did occur but were not associated with specific clinical findings. These findings suggest that typical pineal cysts may be followed up on a clinical basis alone rather than on imaging.

Comparison of patient age with MR imaging features of gangliogliomas.

OBJECTIVE: The purpose of this study was to compare MR imaging features of gangliogliomas in children less than 10 years old with those seen in patients at least 10 years old. MATERIALS AND METHODS: Our study population consisted of 15 female patients and 10 male patients with a mean age of 20 years. The early childhood group was composed of six children with a mean age of 5.5 years. The older group was composed of 19 patients with a mean age of 25.6 years. We assessed tumor volume, tumor location, percentage of tumor that was cystic, pattern of contrast enhancement, and degree of edema. RESULTS: The temporal lobe was the most common tumor location in both groups. Mean tumor volume in the early childhood group was 83 cm3, which was significantly larger than the mean tumor volume (9.78 cm3) for the older group (p = 0.001). Cystic tumors were more common in the early childhood group (83%) than in the older group (63%), and the average percentage of cysts in the cystic tumors was much higher in the early childhood group (67%) than in the older group (30%). Contrast enhancement was seen in five of six early childhood tumors and 13 of 16 tumors in older patients. Four of six tumors in the early childhood group and five of 19 tumors in the older patient group had associated edema. CONCLUSION: The mean tumor volume of gangliogliomas in the early childhood group was significantly larger than that of the older patient group. This finding may be indicative of differences in tumor growth patterns in the two groups, ability of the hemicranium to adjust to mass effect in childhood, or sampling error as a result of a relatively small sample size.

Pictorial review: magnetic resonance angiography of arterial variants at the Circle of Willis.

As intracranial MR angiography becomes more widely used and spatial resolution improves, anomalies at the Circle of Willis which have been previously well described on angiographic studies and anatomic dissections will become more frequently appreciated by MR angiography. Recognition of these variants is important to avoid confusion of the anomalies with aneurysms, evaluate collateral pathways in the intracerebral circulation, and enhance pre-operative planning in patients undergoing surgery at the skull base. In this review, we illustrate several of the more common types of anomalies at the Circle of Willis and discuss the possible clinical significance of each.

Neuroradiologic findings in fucosidosis, a rare lysosomal storage disease.

Fucosidosis is a rare lysosomal storage disorder with the clinical features of mental retardation, cardiomegaly, dysostosis multiplex, progressive neurologic deterioration, and early death. The neuroradiologic findings in two patients are reported, and include abnormalities within the globus pallidus (both patients) and periventricular white matter (one patient).

Lupus-related myelitis: serial MR findings.

PURPOSE: To correlate the MR findings in transverse myelitis secondary to systemic lupus erythematosus with clinical findings during disease exacerbation and remission. METHODS: Four patients (ages 33 to 47 years) with episodes of transverse myelitis secondary to systemic lupus erythematosus were identified. Three patients had recurrent transverse myelitis episodes (one patient with two recurrences), for a total of eight episodes. MR examinations (six after contrast administration) were performed during each transverse myelitis episode, as well as during four periods of remission (in three patients) after therapy with steroids and/or immunosuppressive agents. MR examinations were reviewed for the presence of spinal cord enlargement, intramedullary signal abnormality, and contrast enhancement. RESULTS: Prolongation of T1 or T2 signal (or both) was seen in eight episodes (100%). Spinal cord enlargement was seen in six (75%) of eight transverse myelitis episodes, although it was mild during two episodes. Contrast enhancement was seen in three of six transverse myelitis episodes (dense, inhomogeneous enhancement during two episodes in one patient, and a small focus of enhancement in one patient). During periods of remission, spinal cord diameter returned to normal, and no contrast enhancement was seen, although abnormal signal was present in three examinations performed within 2 months of a transverse myelitis episode. CONCLUSION: Spinal cord widening and signal abnormalities are common MR findings during episodes of transverse myelitis related to systemic lupus erythematosus, and contrast enhancement is less frequently seen. Improvement or resolution of these findings correlates with clinical improvement.

Risk factors in patients undergoing a second aorta-coronary bypass procedure.

A group of 38 patients with a second revascularization procedure was studied for factors which may have contributed to the reappearance of angina after the first operation. Our data indicate that these patients usually have the first operation at an earlier age and had fewer bypasses at that time. In addition, they had inadequate control of the plasma triglyceride and cholesterol levels.