Diffusion-weighted imaging and the apparent diffusion coefficient on 3T MR imaging in the differentiation of craniopharyngiomas and germ cell tumors

Comparison of MRI findings of hypothalamic-optic chiasmatic gliomas and craniopharyngiomas

BACKGROUND

Differential diagnosis of hypothalamic-optic chiasmatic gliomas (HOCGs) and craniopharyngiomas on magnetic resonance imaging (MRI) can be quite challenging.

PURPOSE

To compare the MRI features of HOCGs and cranipharyngiomas.

MATERIAL AND METHODS

Patients diagnosed with HOCG or craniopharyngioma in histopathological evaluation between 2012 and 2022 and who underwent preoperative contrast-enhanced brain MRI were included. Various MRI features were retrospectively evaluated for each lesion: T2-weighted imaging and fluid attenuation inversion recovery hyperintensity, calcification, cystic change, T1-weighted (T1W) imaging hyperintensity of the cystic component, hemorrhage, involvement of sellar, suprasellar or other adjacent structures, lobulated appearance, presence of hydrocephalus, and contrast enhancement pattern. Apparent diffusion coefficient (ADC) values were also evaluated and compared.

RESULTS

Among 38 patients included, 13 (34%) had HOCG and 25 (66%) had craniopharyngioma. Craniopharyngiomas had a significantly higher rate of cystic changes, calcification, and T1W imaging hyperintensity of the cystic component than HOCGs (P <0.05). Of HOCGs, 92% had chiasm involvement, 23% had optic nerve involvement, and 31% had brain stem involvement. On the other hand, chiasm involvement was observed in 8% of craniopharyngiomas, but none had optic nerve and/or brain stem involvement (P <0.05). While 62% (8/13) of HOCGs had diffuse homogeneous enhancement, 80% (20/25) of craniopharyngiomas had a diffuse heterogeneous enhancement pattern. Mean ADC values were significantly higher in craniopharyngiomas compared to HOCGs (2.1 vs. 1.6 ×10-3mm2/s, P <0.05).

CONCLUSION

Although some neuroimaging findings may overlap, features such as presence of cyst and calcification, brain stem and optic pathway involvement, different enhancement patterns, and ADC values may be helpful in the differential diagnosis of HOCGs and craniopharyngiomas.

Clinical and imaging findings for the evaluation of large Rathke's cleft cysts and cystic craniopharyngiomas

PURPOSE

Large Rathke's cleft cysts (LRCCs) and cystic craniopharyngiomas (CCPs) arise from the same embryological origin and may have similar MR presentations. However, the two tumors have different management strategies and outcomes. This study was designed to evaluate the clinical and imaging findings of LRCCs and CCPs, aiming to evaluate their pretreatment diagnosis and outcomes.

METHODS

We retrospectively enrolled 20 patients with LRCCs and 25 patients with CCPs. Both tumors had a maximal diameter of more than 20 mm. We evaluated the patients' clinical and MR imaging findings, including symptoms, management strategies, outcomes, anatomic growth patterns and signal changes.

RESULTS

The age of onset for LRCCs versus CCPs was 49.0 ± 16.8 versus 34.2 ± 22.2 years (p = .022); the following outcomes were observed for LRCCs versus CCPs: (1) postoperative diabetes insipidus: 6/20 (30%) versus 17/25 (68%) (p = .006); and (2) posttreatment recurrence: 2/20 (10%) versus 10/25 (40%) (p = .025). The following MR findings were observed for LRCCs versus CCPs: (1) solid component: 7/20 (35%) versus 21/25 (84%) (p = .001); (2) thick cyst wall: 2/20 (10%) versus 12/25 (48%) (p = .009); (3) intracystic septation: 1/20 (5%) versus 8/25 (32%) (p = .030); (4) snowman shape: 18/20 (90%) versus 1/25 (4%) (p < .001); (5) off-midline extension: 0/0 (0%) versus 10/25 (40%) (p = .001); and (6) oblique angle of the sagittal long axis of the tumor: 89.9° versus 107.1° (p = .001).

CONCLUSIONS

LRCCs can be differentiated from CCPs based on their clinical and imaging findings, especially their specific anatomical growth patterns. We suggest using the pretreatment diagnosis to select the appropriate surgical approach and thus improve the clinical outcome.

The "chameleon" sellar lesions: a case report of unexpected sellar lesions

Introduction

The sellar region and its boundaries represent a challenging area, harboring a variety of tissues of different linings. Therefore, a variety of diseases can arise or involve in this area (i.e., neoplastic or not). A total of three challenging cases of "chameleon" sellar lesions treated via EEA were described, and the lesions mimicked radiological features of common sellar masses such as craniopharyngiomas and/or pituitary adenomas, and we also report a literature review of similar cases.

Methods

A retrospective analysis of three primary cases was conducted at the Università degli Studi di Napoli Federico II, Naples, Italy. Clinical information, radiological examinations, and pathology reports were illustrated.

Results

A total of three cases of so-called "chameleon" sellar lesions comprising two men and one woman were reported. Based on the intraoperative finding and pathological examination, we noticed that case 1 had suprasellar glioblastoma, case 2 had a primary neuroendocrine tumor, and case 3 had cavernous malformation.

Conclusion

Neurosurgeons should consider "unexpected" lesions of the sellar/suprasellar region in the preoperative differential diagnosis. A multidisciplinary approach with the collaboration of neurosurgeons, neuroradiologists, and pathologists plays a fundamental role. The recognition of unusual sellar lesions can help surgeons with better preoperative planning; so an endoscopic endonasal approach may represent a valid surgical technique to obtain decompression of the optic apparatus and vascular structures and finally a pathological diagnosis.

Brain and Spinal Tumors Originating from the Germ Line Cells

Primary central nervous system germ cell tumors (CNS GCTs) are part of the GCTs in children and adults. This tumor entity presents with geographic variation, age, and sex predilection. There are two age peaks of incidence distribution at the first few months of life and in adolescence. CNS GCTs are heterogeneous in histopathological subtypes, locations, and tumor marker (AFP, β-hCG) secretions. In the WHO CNS tumor classification, GCTS are classified as germinoma and nongerminomatous GCT (NGGCT) with different subtypes (including teratoma). Excluding mature teratoma, the remaining NGGCTs are malignant (NGMGCT). In teratoma, growing teratoma syndrome and teratoma with somatic-type malignancy should be highlighted. The common intracranial locations are pineal region, neurohypophysis (NH), bifocal pineal-NH, basal ganglia, and cerebral ventricle. Above 50% of intracranial GCTs (IGCTs) present obstructive hydrocephalus. Spinal tumors are rare. Age, locations, hydrocephalus, and serum/CSF titer of β-hCG correlate with clinical manifestations. Delayed diagnosis is common in tumors arising in neurohypophysis, bifocal, and basal ganglia resulting in the increasing of physical dysfunction and hormonal deficits. Staging work-up includes CSF cytology for tumor cells and contrast-enhanced MRI of brain and spine for macroscopic metastasis before treatment commences. The therapeutic approach of CNS GCTs integrates locations, histopathology, staging, tumor marker level, and therapeutic classification. Treatment strategies include surgical biopsy/excision, chemotherapy, radiotherapy (single or combination). Secreting tumors with consistent imaging may not require histopathological diagnosis. Primary germinomas are highly radiosensitive and the therapeutic aim is to maintain high survival rate using optimal radiotherapy regimen with/without chemotherapy combination. Primary NGNGCTs are less radiosensitive. The therapeutic aim is to increase survival utilizing more intensive chemotherapy and radiotherapy. The negative prognostic factors are residue disease at the end of treatment and serum or CSF AFP level >1000 ng/mL at diagnosis. In refractory or recurrent NMGGCTs, besides high-dose chemotherapy, new therapy is necessary. Molecular profiling and analysis help for translational research. Survivors of pediatric brain tumors frequently experience cancer-related cognitive dysfunction, physical disability, pituitary hormone deficiency, and other CNS complications after cranial radiotherapy. Continuous surveillance and assessment may lead to improvements in treatment protocols, transdisciplinary interventions, after-treatment rehabilitation, and quality of life.

Xanthogranuloma of the Sellar Region: A Comprehensive Review of Neuroimaging in a Rare Inflammatory Entity

Xanthogranuloma of the sellar region is a rare chronic inflammatory lesion resulting from secondary hemorrhage, inflammation, infarction, and necrosis of an existing Rathke’s cleft cyst, craniopharyngioma, or pituitary adenoma. Sellar xanthogranulomas are challenging to differentiate from other cystic lesions preoperatively due to the lack of characteristic imaging features. We performed a literature overview of the clinical and paraclinical features, treatment options, and long-term outcomes of patients with sellar xanthogranuloma, focusing on the preoperative radiological diagnosis. The hyperintense signal in both T1- and T2-weighted sequences, cystic or partially cystic morphology, ovoid shape, sellar epicenter, intra- and suprasellar location, intratumoral calcifications, linear rim contrast enhancement, and the absence of cavernous sinus invasion suggest xanthogranuloma in the preoperative differential diagnosis. An endoscopic endonasal gross total resection without radiotherapy is the preferred first-line treatment. Given the low rate of recurrence rate and low chance of endocrinological recovery, a mass reduction with decompression of the optic apparatus may represent an appropriate surgical goal. Identifying the xanthogranulomas’ mutational profile could complement histopathological diagnosis and give insight into their histo-pathogenesis. A better preoperative neuroimagistic diagnosis of sellar xanthogranulomas and differentiation from lesions with a poorer prognosis, such as craniopharyngioma, would result in an optimal personalized surgical approach.

Differentiation between Germinoma and Craniopharyngioma Using Radiomics-Based Machine Learning

For the tumors located in the anterior skull base, germinoma and craniopharyngioma (CP) are unusual types with similar clinical manifestations and imaging features. The difference in treatment strategies and outcomes of patients highlights the importance of making an accurate preoperative diagnosis. This retrospective study enrolled 107 patients diagnosed with germinoma (n = 44) and CP (n = 63). The region of interest (ROI) was drawn independently by two researchers. Radiomic features were extracted from contrast-enhanced T1WI and T2WI sequences. Here, we established the diagnosis models with a combination of three selection methods, as well as three classifiers. After training the models, their performances were evaluated on the independent validation cohort and compared based on the index of the area under the receiver operating characteristic curve (AUC) in the validation cohort. Nine models were established and compared to find the optimal one defined with the highest AUC in the validation cohort. For the models applied in the contrast-enhanced T1WI images, RF_S + RF_C and LASSO + LDA were observed to be the optimal models with AUCs of 0.91. For the models applied in the T2WI images, DC + LDA and LASSO + LDA were observed to be the optimal models with AUCs of 0.88. The evidence of this study indicated that radiomics-based machine learning could be potentially considered as the radiological method in the presurgical differential diagnosis of germinoma and CP with a reliable diagnostic performance.

Diffusion-weighted imaging for predicting tumor consistency and extent of resection in patients with pituitary adenoma

This study aimed to investigate the role of diffusion-weighted imaging (DWI) in predicting tumor consistency, extent of surgical resection, and recurrence in pituitary adenoma (PA). We reviewed a prospectively collected database of surgically treated PA between March 2016 and October 2017. Predictors for extent of resection and recurrence/progression were assessed with logistic and Cox regression analysis. Of the 183 patients, the tumor consistency was found soft in 107 (58.5%) patients, intermediate in 41 (22.4%) patients, and hard in 35 (19.1%) patients. The mean of ADC ratio was 0.92 ± 0.22 for hard tumor, 1.03 ± 0.22 for intermediate tumor, and 1.41 ± 0.62 for soft tumor (P < 0.001). The mean collagen content was 25.86% ± 15.00% for hard tumor, 16.05% ± 9.90% for intermediate tumor, and 5.00% ± 6.00% for soft tumor (P < 0.001). Spearman analysis showed a significant correlation between ADC ratio and collagen content (ρ = - 0.367; P < 0.001). Gross-total resection (GTR) was obtained in 68.3% of patients, and multivariable logistic regression analysis showed that ADC ratio (OR, 12.135; 95% CI, 4.001-36.804; P < 0.001), giant PA (OR, 0.233; 95% CI, 0.105-0.520; P < 0.001), and invasion (OR, 0.459; 95% CI, 0.220-0.960; P = 0.039) were significantly predictive of GTR. Twenty-seven (14.8%) patients suffered recurrence/progression in the mean follow-up of 35.14 months. Invasion (HR, 2.728; 95% CI, 1.262-5.899; P = 0.011) was identified as independent predictors of recurrence/progression. ADC ratio of DWI could be used for preoperative assessment of tumor consistency, tumor collagen content, and extent of surgical resection, which might be useful in preoperative planning for patients with PA.

Advantage of high b value diffusion-weighted imaging for differentiation of common pediatric brain tumors in posterior fossa

PURPOSE

The pediatric posterior fossa (PF) brain tumors with higher frequencies are embryonal tumors (ET), ependymal tumors (EPN) and pilocytic astrocytomas (PA), however, it is often difficult to make a differential diagnosis among them with conventional MRI. The ADC calculated from DWI could be beneficial for diagnostic work up.

METHOD

We acquired DWI at b = 1000 and 4000(s/mm²). The relationship between ADC and the three types of brain tumors was evaluated with Mann-Whitney U test. We also performed simple linear regression analysis to evaluate the relationship between ADC and cellularity, and implemented receiver operating characteristic curve (ROC curve) to test the diagnostic performance among tumors.

RESULTS

The highest ADC (b1000/b4000 × 10^-3 mm²/s) was observed in PA (1.02-1.91/0.73-1.28), followed by PF-EPN (0.83-1.28/0.60-0.79) and the lowest was ET (0.41-0.75/0.29-0.47). There was significant difference among the groups in both ADC value (b-1000/b-4000: ET vs. PF-EPN p < 0.0001/0.0001, ET vs. PA p < 0.0001/0.0001, PF-EPN vs. PA p < 0.0001/0.0001). ROC analysis revealed that ADC in both b-values showed complete separation between ET and PF-EPN. And it also revealed that ADC at b-4000 could differentiate PF-EPN and PA (96.0%) better than ADC at b-1000 (90.1%). The stronger negative correlation was observed between the ADC and cellularity at b-4000 than at b-1000 (R²  = 0.7415 vs.0.7070) CONCLUSIONS: ADC of ET was significantly lower than the other two groups, and ADC of PA was significantly higher than the other two groups in both b-1000 and b-4000. Our results showed that ADC at b-4000 was more useful than ADC at b-1000 especially for differentiation between PF-EPN and PA.

Accuracy of apparent diffusion coefficient values and magnetic resonance imaging in differentiating suprasellar germinomas from chiasmatic/hypothalamic gliomas

OBJECTIVE

The aim of this study was to differentiate suprasellar germinomas from chiasmatic/hypothalamic gliomas (CHGs) using apparent diffusion coefficient (ADC) values and magnetic resonance imaging (MRI) characteristics.

MATERIALS AND METHODS

A cross-sectional study was conducted on 11 patients with suprasellar germinomas and 11 patients with CHGs who underwent pretreatment MRI. The ADC values (minimum and average ADC values) of the tumors were measured and the MRI characteristics were evaluated.

RESULTS

The average and minimum ADC values of suprasellar germinomas were significantly lower than those of CHGs (p = 0.016 and 0.004 respectively). The selection of 941.15 × 10^-6 mm²/s as a cutoff value of the minimum ADC value was used to differentiate suprasellar germinomas and CHGs; the best results were obtained with area under the curve of 0.889, sensitivity of 87.5%, specificity of 77.8% and accuracy of 82.4%. MRI characteristics suggested the diagnosis of suprasellar germinomas were T2W hypointensity and involvement of pituitary gland and/or stalk. MRI characteristics suggested the diagnosis of CHGs was higher degree of contrast enhancement and presence of macrocysts.

CONCLUSION

ADC values have a role in differentiating suprasellar germinomas and CHGs, especially when imaging findings on conventional MRI are inconclusive. Furthermore, some MRI features are in favor of differentiation between these tumor entities including tumor location, cyst pattern, T2W hypointensity, degree of contrast enhancement, stalk and pituitary gland involvement.

Characterization of the murine orthotopic adamantinomatous craniopharyngioma PDX model by MRI in correlation with histology

PURPOSE

Adamantinomatous craniopharyngiomas (ACP) as benign sellar brain tumors are challenging to treat. In order to develop robust in vivo drug testing methodology, the murine orthotopic craniopharyngioma model (PDX) was characterized by magnetic resonance imaging (MRI) and histology in xenografts from three patients (ACP1-3).

METHODS

In ACP PDX, multiparametric MRI was conducted to assess morphologic characteristics such as contrast-enhancing tumor volume (CETV) as well as functional parameters from dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) including area-under-the-curve (AUC), peak enhancement (PE), time-to-peak (TTP) and apparent diffusion coefficient (ADC). These MRI parameters evaluated in 27 ACP PDX were correlated to histological features and percentage of vital tumor cell content.

RESULTS

Qualitative analysis of MRI and histology from PDX revealed a similar phenotype as seen in patients, although the MRI appearance in mice resulted in a more solid tumor growth than in humans. CETV were significantly higher in ACP2 xenografts relative to ACP1 and ACP3 which correspond to respective average vitality of 41%, <10% and 26% determined histologically. Importantly, CETV prove tumor growth of ACP2 PDX as it significantly increases in longitudinal follow-up of 110 days. Furthermore, xenografts from ACP2 revealed a significantly higher AUC, PE and TTP in comparison to ACP3, and significantly increased ADC relative to ACP1 and ACP3 respectively. Overall, DCE-MRI and DWI can be used to distinguish vital from non-vital grafts, when using a cut off value of 15% for vital tumor cell content.

CONCLUSIONS

MRI enables the assessment of craniopharyngioma PDX vitality in vivo as validated histologically.

Small Cell Glioblastoma of the Sella Turcica Region: Case Report and Review of the Literature

BACKGROUND

Glioblastomas in the sellar region are very rare; in most cases, the tumor originates from the optic nerve or optic chiasm. Only 4 cases of sellar glioblastoma with a nonoptic origin have been reported. We present such a case with detailed clinical, imaging, and histopathologic information. We also review similar published cases.

CASE DESCRIPTION

A 42-year-old woman presented with endocrinologic abnormalities, including amenorrhea and lactation, symptoms of diabetes insipidus, and signs of elevated intracranial pressure. Magnetic resonance imaging showed a giant, heterogeneously enhancing lesion involving the intrasellar, parasellar, and suprasellar regions, with hypercellularity and signs of infiltration of adjacent structures. Intraoperative examination revealed the tumor to be independent from the optic pathways, but it showed infiltration of the hypothalamic region. Histopathologic examination demonstrated uniformly packed small cells and negative staining for glial fibrillary acidic protein, which was consistent with a diagnosis of small cell glioblastoma.

CONCLUSIONS

This is the first report of a small cell glioblastoma in the sella turcica region. Glioblastomas in the sellar region with no clear evidence of an optic origin should be viewed as an independent disease entity. The typical characteristics of this tumor indicate it should be considered a rare subtype of glioblastoma. Further accumulation of experience is needed to better differentiate these cases and to offer optimal treatment.

Pitfalls of Neuroendoscopic Biopsy of Intraventricular Germ Cell Tumors

OBJECTIVE

A neuroendoscopic biopsy has become common for the diagnosis of ventricular tumors. However, its utility in patients with germ cell tumors (GCTs) has not been well discussed. We examined the usefulness and pitfalls of neuroendoscopic biopsies of intraventricular GCTs at a single institution.

METHODS

We retrospectively studied 21 consecutive patients diagnosed with GCTs by a neuroendoscopic biopsy of the ventricular region via the lateral ventricle. We examined the localization of tumors, histologic diagnoses using biopsies, surgical complications, and consistency of the diagnosis at the latest follow-up.

RESULTS

Tumor specimens were obtained from a pineal lesion (n = 20), neurohypophysial lesion (n = 5), and lateral ventricular wall lesion (n = 2). In 5 patients, the specimens were obtained from multiple areas. The initial diagnoses were pure germinoma (n = 16), immature teratoma (n = 1), yolk sac tumor (n = 1), and mixed GCT (n = 3). Six of 21 patients needed a second transcranial removal of enhanced residual lesions in the course of the treatment. A discrepancy in the histologic diagnosis between 2 surgeries occurred in 3 patients: All 3 patients had a new diagnosis of teratoma component following transcranial surgery. No postoperative mortality or permanent morbidity related to the neuroendoscopic procedures was noted.

CONCLUSION

Neuroendoscopic biopsies are safe and useful for obtaining reliable histologic diagnoses in the management of GCTs. However, for GCTs with mixed histology, biopsies are susceptible to diagnostic errors, especially missing detecting a component of teratoma.

Role of diffusion-weighted imaging in skull base lesions: A pictorial review

Skull base lesions can be related to wide number of pathologies including infections, benign and malignant tumors. Accurate diagnosis and differentiation between these entities is important for prompt and appropriate treatment. However, computed tomography and routine magnetic resonance imaging techniques only provide information on the extent of the lesions, with limited ability to differentiate between benign and malignant lesions. Diffusion-weighted imaging can help in many such situations by providing additional information, including help in differentiating benign from malignant lesions, so that appropriate treatment can be initiated. In this review article, we illustrate the imaging findings of the spectrum of skull base lesions, emphasizing the role of diffusion-weighted imaging in this domain.

MRI features of pediatric intracranial germ cell tumor subtypes

Intracranial germ cell tumors differ in histology and location, and require different clinical management strategies. We characterized the imaging features that may aid pre-operative differentiation of intracranial germinomas and non-germinomatous germ cell tumors (NGGCTs). This retrospective study analyzed 85 patients with intracranial germ cell tumors and adequate preoperative or pretreatment MRIs between 2000 and 2013 at our institution. Pretreatment MRI characteristics, apparent diffusion coefficient (ADC) values, tumor histopathology, and patient outcomes were compared. NGGCTs occurred in the pineal region and cerebral hemispheres more often than germinomas; all bifocal lesions were germinomas. NGGCTs (36.6 ± 17.0 mm) were significantly larger than germinomas (25.7 ± 11.6 mm; P = 0.002). The presence of pure solid tumor (45.5 vs. 20.0%, P = 0.033) and an infiltrative margin (20.0 vs. 3.3%, P = 0.035) were significantly more common in germinomas than NGGCTs. The presence of intratumoral T1 hyperintense foci (66.7 vs. 10.9%, P < 0.001) and moderate/marked enhancement (86.7 vs. 50.9%, P < 0.001) were significantly more common in NGGCTs than in germinomas. Mean ADC_mean values (×10^-3 mm²/s) were significantly lower in germinomas (1.113 ± 0.415) than in NGGCTs (2.011 ± 0.694, P = 0.001). Combined a lack of T1 hyperintense foci and an ADC_mean threshold value (1.143 × 10^-3 mm²/s) had the highest specificity (91.3%) and positive predictive value (92.3%), while the combination of lack of a T1 hyperintensense foci, no/mild enhancement, and an ADC_mean threshold value had 100% sensitivity and 100% negative-predictive value for discriminating germinomas from NGGCTs. Pre-operative conventional MRI characteristics and diffusion-weighted MRI help clinicians to assess patients with intracranial germ cell tumors. Tumor size, location, T1 hyperintense foci, intratumoral cystic components, tumor margin and enhancing patterns demonstrate contrast between germinomas and NGGCTs. Serum tumor markers and adjunctive combination with T1 hyperintensity and/or enhancing pattern with ADC offer potential in preoperative differentiating intracranial germinomas and NGGCTs.

Advantage of High b Value Diffusion-Weighted Imaging for Differentiation of Hemangioblastoma from Brain Metastases in Posterior Fossa

OBJECTIVE

It is sometimes difficult to make a differential diagnosis between brain metastases and hemangioblastomas in the posterior fossa. We assessed whether high b value diffusion-weighted image (DWI) at b = 4000 could differentiate these tumors.

METHODS

We acquired DWI at 3-T magnetic resonance imaging with b = 1000 and b = 4000 seconds/mm² in histologically confirmed 12 patients of hemangioblastoma without von Hippel-Lindau disease and 16 patients with brain metastases originating at the posterior fossa. Apparent diffusion coefficient (ADC) values were measured by manually placing regions of interest on ADC maps at the site of enhanced tumor confirmed on contrast-enhanced T1- weighed image. ADC was expressed as the minimum (ADC_MIN), mean (ADC_MEAN), and maximum (ADC_MAX) values.

RESULTS

All the ADC values of hemangioblastomas were statistically higher than those of metastatic tumor in both b = 1000 and b = 4000 (P < 0.0001 in ADC_MIN, ADC_MEAN, and ADC_MAX; Mann-Whitney U test). With the cutoff value at 0.6 × 10^-3 mm²/second, the positive predictive value of ADC_MIN at b = 4000 was higher than that of ADC_MIN at b = 1000 (100% vs. 89.3%, logistic analysis) to differentiate hemangioblastomas from brain metastases. Moreover, we studied the pathologic subtype of hemangioblastoma and confirmed that ADCs (b = 4000_MIN) of cellular subtype were statistically lower than those of reticular subtype (P = 0.03; Mann-Whitney U test).

CONCLUSIONS

High b value DWI reflects diffusion more accurately than does regular b value. Our results showed that ADC calculation by high b value (b = 4000) DWI at 3-T magnetic resonance imaging is clinically useful for differentiating hemangioblastomas from brain metastases.