Comparative Evaluation of Lower Gadolinium Doses for MR Imaging of Meningiomas: How Low Can We Go?

BACKGROUND AND PURPOSE: Gadolinium-based contrast agents are widely used for meningioma imaging; however, concerns exist regarding their side effects, cost, and environmental impact. At the standard gadolinium dose, most meningiomas show avid contrast enhancement suggesting that administering a smaller dose may be feasible. The purpose of this study was to evaluate the impact of a lower gadolinium dose on the differentiation between meningiomas and adjacent intracranial tissues. MATERIALS AND METHODS: 108 patients with presumed or confirmed meningiomas who underwent brain MRI at multiple doses of gadolinium were included in the study. The patients' MRIs were categorized into three groups based on the gadolinium dose administered: Micro (approximately 25% of the standard dose), Low (approximately 62% of the standard dose) and Standard dose. Multi-reader qualitative visual assessment and quantitative relative signal differences calculations were performed to evaluate tumor differentiation from the cortex and from the dural venous sinus. The relative signal differences for each dose were analyzed using ANOVA for quantitative assessment and NcNemar for qualitative assessment. Additionally, non-inferiority testing was used to compare the Low and Micro doses to the Standard dose. RESULTS: Decreasing the gadolinium dose to a Low dose or a Micro dose resulted in a statistically significant decrease in signal difference between the tumor and the adjacent brain tissues (p<0.02). However, on visual assessment, the Low dose was non-inferior to the Standard dose. The proportion of cases with suboptimal differentiation was significantly higher for the Micro dose than for the Standard dose, both for the differentiation between the tumor and the cortex (p=0.041) and the differentiation between tumor and sinus (p<0.001). CONCLUSIONS: Reducing the gadolinium dose to 62% of the standard level still allows for sufficient visual delineation of meningiomas from surrounding tissues. However, further reduction to 25% substantially compromises the ability to distinguish the tumor from adjacent structures and is, therefore, not advisable. ABBREVIATIONS: GBCAs = Gadolinium-based contrast agents; SSS = Superior Sagittal Sinus.

Pattern of Recurrence of Glioblastoma Versus Grade 4 IDH-Mutant Astrocytoma Following Chemoradiation: A Retrospective Matched-Cohort Analysis.

Background and Purpose: To quantitatively compare the recurrence patterns of glioblastoma (isocitrate dehydrogenase-wild type) versus grade 4 isocitrate dehydrogenase-mutant astrocytoma (wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase, respectively) following primary chemoradiation. Materials and Methods: A retrospective matched cohort of 22 wild type isocitrate dehydrogenase and 22 mutant isocitrate dehydrogenase patients were matched by sex, extent of resection, and corpus callosum involvement. The recurrent gross tumor volume was compared to the original gross tumor volume and clinical target volume contours from radiotherapy planning. Failure patterns were quantified by the incidence and volume of the recurrent gross tumor volume outside the gross tumor volume and clinical target volume, and positional differences of the recurrent gross tumor volume centroid from the gross tumor volume and clinical target volume. Results: The gross tumor volume was smaller for wild type isocitrate dehydrogenase patients compared to the mutant isocitrate dehydrogenase cohort (mean ± SD: 46.5 ± 26.0 cm3 vs 72.2 ± 45.4 cm3, P = .026). The recurrent gross tumor volume was 10.7 ± 26.9 cm3 and 46.9 ± 55.0 cm3 smaller than the gross tumor volume for the same groups (P = .018). The recurrent gross tumor volume extended outside the gross tumor volume in 22 (100%) and 15 (68%) (P= .009) of wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase patients, respectively; however, the volume of recurrent gross tumor volume outside the gross tumor volume was not significantly different (12.4 ± 16.1 cm3 vs 8.4 ± 14.2 cm3, P = .443). The recurrent gross tumor volume centroid was within 5.7 mm of the closest gross tumor volume edge for 21 (95%) and 22 (100%) of wild type isocitrate dehydrogenase and mutant isocitrate dehydrogenase patients, respectively. Conclusion: The recurrent gross tumor volume extended beyond the gross tumor volume less often in mutant isocitrate dehydrogenase patients possibly implying a differential response to chemoradiotherapy and suggesting isocitrate dehydrogenase status might be used to personalize radiotherapy. The results require validation in prospective randomized trials.

Incidence and Time of Onset of Osseous Pseudoprogression in Patients With Metastatic Spine Disease From Renal Cell or Prostate Carcinoma After Treatment With Stereotactic Body Radiation Therapy.

BACKGROUND: Tumor osseous pseudoprogression (PP), defined as an imaging-based transient increase in tumor size following treatment, was recently described in patients with spinal metastases following stereotactic body radiation therapy. Distinguishing PP from true tumor progression is critical. OBJECTIVE: To describe the incidence, time of onset, and time range of PP following stereotactic body radiation therapy in patients treated for spinal metastases from either prostate cancer (PC) or renal cell carcinoma (RCC), and associated predictive factors. METHODS: A retrospective study was conducted on our institution's cancer database from 2009 to 2015. Selection was based on single level, no prior radiation or surgery, ≥2 follow-up spine magnetic resonance imaging (MRI), and metastases arising from either PC or RCC. Gross tumor volume was contoured on pre- and up to 5 posttreatment MRIs. Patients were sorted into groups depending on gross tumor volume response: PP, non-PP, or progressive disease. Clinical and dosimetric variables were compared using either Fisher's exact test or Kruskal-Wallis analyses. RESULTS: Forty-three spinal segments from 31 patients were analyzed. RCC and PC patients showed similar incidence of PP (∼37%). Whether the primary was lytic or sclerotic was a significant predictive factor with more PP in the lytic group (P = .0208). There was a trend of earlier PP onset in RCC (within 6-18 mo) as compared to PC; however, PC segments showed more time-confined presentation of PP (9-12 mo). CONCLUSION: There was a higher incidence of PP in lytic compared to sclerotic primary tumor type. PP in spinal metastatic sites may have variable presentations depending on the primary cancer.

Incidence of Dural Venous Sinus Thrombosis in Patients with Glioblastoma and Its Implications.

OBJECTIVE: Glioblastoma (GBM) is associated with increased risk of developing dural venous sinus thrombosis (DVST), which often goes undiagnosed as symptoms are readily attributed to tumor. The purpose of this study was to investigate the incidence of DVST, potential predictive features on imaging, complications, its effect on survival, and time of greatest risk for developing DVST. METHODS: A retrospective search of patients with GBM who had surgery followed by chemotherapy and/or radiation therapy between 2009 and 2015 at our institution was performed. Magnetic resonance imaging studies of the brain were reviewed on volumetric postgadolinium T1-weighted sequences for DVST. Tumors were characterized using the Visually Accessible REMBRANDT (Repository for Molecular Brain Neoplasia Data) Images classification, and identified thromboses were tracked for propagation, regression, or resolution. Statistical analyses were directed at identifying clinical predictors and survival differences between the DVST and no-DVST groups. RESULTS: In total, 163 cases totaling 1637 scans, were reviewed; 12 patients (7.4%) developed DVST, of whom 11 presented with thrombus before any treatment. Tumor invasion of dural sinuses and greater T1/fluid-attenuated inversion recovery ratios were significantly associated with thrombus development (P = 0.02 and P = 0.02, respectively). In patients who developed DVST, thrombosis was more likely to develop ipsilateral to tumor side (P = 0.01) and was associated with a greater likelihood of developing extracranial venous thromboembolism (P = 0.012). There were no venous infarcts and no significant difference in survival between groups (P = 0.83). CONCLUSIONS: Patients with GBM have increased risk of developing DVST, independent of surgical treatment or chemoradiation. DVST presence does not affect survival. Tumor invasion of dural sinuses and greater T1/fluid-attenuated inversion recovery ratio on preoperative imaging were the most significant predictors of DVST development.