T2-FLAIR Mismatch Sign and Response to Radiotherapy in Diffuse Intrinsic Pontine Glioma.

PURPOSE: The T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign was previously reported as a diagnostic indicator of diffuse astrocytoma, isocitrate dehydrogenase-mutant, and 1p/19q noncodeletion. Subsequently, it was reported that the same findings were observed in diffuse intrinsic pontine glioma (DIPG). We investigated the clinical significance of T2-FLAIR mismatch sign in DIPG. METHODS: Twenty-one patients with DIPG (Male: Female = 12:9) were treated at our institute between 2004 and 2019. All patients were treated with local radiotherapy of 54 Gy/30 fractions. The positive T2-FLAIR mismatch sign was defined if it fulfilled the following criteria: (1) T2-FLAIR mismatch volume was >50% of T2 high volume at nonenhanced area, (2) the FLAIR low lesion is not associated with gadolinium enhancement (inside of enhancement or just outside of enhancement defined as edema), and (3) signal-intensity of FLAIR lowest lesion at tumor is lower than the normal cerebellar cortex. RESULTS: In our patient series, T2-FLAIR mismatch sign was found in 5 out of 21 patients. Objective response rate of radiotherapy was 100% in patients positive for T2-FLAIR mismatch, while it was 25.0% in patients negative for T2-FLAIR mismatch, and this difference was statistically significant (p < 0.01, Fisher's exact test). In patients under the age of 18-years, T2-FLAIR mismatch positive had a slightly better prognosis (p < 0.05, Wilcoxon test). CONCLUSION: T2-FLAIR mismatch sign in DIPG may be an indicator for better response to radiotherapy and a better prognostic factor.

[Treatment of secondary engraftment failure with granulocyte colony-stimulating factor and eltrombopag after allogeneic peripheral blood stem cell transplantation in adult T-cell leukemia/lymphoma].

A 67-year-old woman diagnosed with adult T-cell leukemia/lymphoma received an induction chemotherapy and showed a partial response. She then underwent allogeneic peripheral blood stem cell transplantation from an HLA-identical sibling donor. Although cyclosporine (CS) was stopped at 120 days after transplantation, chronic graft-versus-host disease (cGVHD) of the skin developed. She was treated with a topical steroid, without exacerbation of the GVHD. She was admitted to our hospital due to the sudden development of pancytopenia at 212 days after the transplantation. She had an EB virus-associated post-transplant lymphoproliferative disorder (PTLD) in the hilum of the lung. The cGVHD of the skin resolved after the administration of prednisolone and CS. However, pancytopenia and PTLD persisted. Treatment with four cycles of rituximab (4×375 mg/m2/week) led to the complete resolution of PTLD, but transfusion-dependent cytopenia did not improve. Secondary engraftment failure was diagnosed, and granulocyte colony-stimulating factor (G-CSF) and eltrombopag (100 mg/day) were administered, leading to gradual improvement of pancytopenia. It was observed that persistent pancytopenia was caused by secondary engraftment failure due to cGVHD in this case. This case suggested that the treatment with G-CSF and eltrombopag is effective for cGVHD-associated secondary engraftment failure.

Bevacizumab for optic pathway glioma with worsening visual field in absence of imaging progression: 2 case reports and literature review.

Children with optic pathway gliomas (OPGs) frequently suffer from problems of visual function resulting from tumors. Previous reports showed that bevacizumab improved visual function in patients with OPG via tumor response to treatment. In these two case reports, we show that bevacizumab improved visual field without tumor response as seen in imaging. Both, a 10-year-old girl and a 6-year-old boy, had previous history of treatment with platinum-based chemotherapy. They had visual deterioration without tumor progression on MR imaging. Bevacizumab effectively and immediately improved visual field in both patients without imaging response of OPG. We emphasize that bevacizumab should be considered for patients with OPGs having visual deterioration without tumor progression.

Immunostaining of Increased Expression of Enhancer of Zeste Homolog 2 (EZH2) in Diffuse Midline Glioma H3K27M-Mutant Patients with Poor Survival.

INTRODUCTION: The interaction of K27M mutation in histone H3 (H3K27M mutation) with polycomb repressive complex 2 (PRC2) is facilitated by the enhancer of zeste homolog 2 (EZH2). Subsequently, this interaction leads to the global reduction level of H3K27me3. We analyzed the EZH2 expression level in H3K27M mutation-positive tumors and revealed the association of high EZH2 expression with poor survival. METHODS: Our study included 12 patients, with an age range of 6-56 years and treated between 2007 and 2016. All patients underwent MRI study for nonenhanced T1, T2, diffusion, gadolinium-enhanced T1-weighted imaging, and fluid-attenuated inversion recovery (FLAIR). Immunohistochemical staining was performed against H3K27M, H3K27me3, EZH2, EED, mutant isocitrate dehydrogenase 1 (IDH1), α-thalassemia X-linked intellectual disability (ATRX), p53, O6-methylguanine-DNA methyltransferase (MGMT), and Ki-67 antibodies. RESULTS: All patients were negative for IDH1R132H and H3K27me3, but H3K27M-positive. Staining against EZH2 was negative in all histological features of grade II cases (3/12) and positive in grade III and IV cases; EZH2 positivity is associated with poor prognosis (p = 0.0082). EZH2 positivity was not associated with EED positivity. Retained ATRX staining was found mostly in grade III and IV cases (6/12). P53 was predominantly positive in cases of astrocytoma and glioblastoma (8/12). The labeling index of Ki-67 was 1.2-31.4% for grade II and III histological features and 11.2-24.8% for grade IV. CONCLUSION: We suggest that the expression of EZH2 is not associated with the PRC2 pathway and increases in patients with H3K27M-mutant diffuse midline glioma and a poor prognosis. Further studies are necessary to understand the mechanism involved.

[Weekly Vinblastine in Pediatric Optic Pathway/Hypothalamic Glioma:2 Cases Report].

It is reported that vinblastine monotherapy has promising activity in patients with pediatric optic pathway/hypothalamic glioma(OPHG)who experienced treatment failure after initial treatment with standard chemotherapy. However, there have been no reports on vinblastine monotherapy against OPHG in Japan. Since vinblastine is an unauthorized drug under the Ministry of Health and Welfare, we used it after completing an in-hospital institutional review board application for each case. In the first case, a 6-year-old boy with recurrent OPHG with hydrocephalus was referred to our hospital. Weekly vinblastine was started at a dose of 6mg/m2 and was then reduced to 5mg/m2 and 4mg/m2 sequentially due to hematotoxicity. After 11 cycles of vinblastine, improvement in hydrocephalus was observed. After 22 cycles of vinblastine, the best response was observed, and we continued treatment up to 35 cycles. Progression of the disease was observed after 47 cycles and then we changed treatment to another regimen after 48 cycles of vinblastine. In the second case, a 6-year-old boy with chemotherapy-naïve recurrent OPHG underwent chemotherapy with vincristine and carboplatin. After 9 treatment cycles with carboplatin, hypersensitivity was observed. Subsequently, he was treated using weekly vinblastine as per the same protocol as that in our first case. A moderate response was observed after 18 cycles of vinblastine. After 48 cycles of vinblastine, the best response was observed, and we completed treatment. In both cases, severe adverse events were not observed and the treatment was well-tolerated. Vinblastine administered once per week is well-tolerated and maintains quality of life in children with OPHG.

Myeloid sarcoma with plasmacytoid dendritic cell-like proliferation associated with IKZF1, ETV6 and DNMT3A mutations.

The classification of clonal plasmacytoid dendritic cell (pDC) proliferation associated with myeloid neoplasms remains a topic of ongoing debate. Although the fifth edition of the World Health Organization classification classifies clonal pDC proliferation into two categories, it is unclear whether this classification adequately captures the complexities of clonal pDC pathogenesis. We present a clinical case featuring myeloid sarcoma with pDC-like cells in cervical lymph nodes and bone marrow (BM). Analysis of biopsy specimens and BM aspirate revealed two distinct cellular populations expressing myeloid and pDC markers. One population exhibited myeloid leukemia and monocyte markers, including MPO, CD13, CD33, CD11b, and CD14, while the other manifested an immunophenotype reminiscent of pDCs, characterized by expression of CD56 and CD123. Additionally, whole exome sequencing and RNA sequencing of BM mononuclear cells were conducted to explore the pathophysiology of this rare malignancy, and unveiled pDC-like cell proliferation driven by IKZF1 and ETV6 mutations originating from clonal hematopoiesis initiated by a DNMT3A mutation. Notably, venetoclax-based therapy exhibited efficacy for achieving and sustaining complete remission. This case provides pivotal insights into the mechanistic aspects of pDC/pDC-like cell proliferation in myeloid sarcoma, offering valuable perspectives on therapeutic strategies.

High Efficacy and Safety of Asciminib in a Chronic Myeloid Leukemia Patient with Chronic Kidney Disease Following Renal Transplantation.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm driven by the BCR::ABL1 tyrosine kinase. Tyrosine kinase inhibitors (TKIs) have been established as standard therapies for CML. However, some CML patients experience TKI intolerance. Asciminib was approved for CML patients either intolerant or refractory to TKI therapy. We herein report a 63-year-old CML patient who underwent renal transplantation and exhibited TKI intolerance. He was switched to asciminib, which achieved a deep molecular response without exacerbation of the renal function. Our experience revealed that asciminib is effective and safe for CML patients complicated with chronic kidney disease.

[A case of occipital diploic dermoid tumor with perforation of the dura].

Along with epidermoid cysts, dermoid cysts are uncommon, benign and slow-growing lesions. We described a case of diploic dermoid cyst of the occipital bone with an intracranial extension in the right posterior fossa diagnosed and subjected to pathological examination. A 63-year-old man presented with dizziness at the time of posture conversion. Magnetic resonance imaging(MRI)showed a heterogenous hypo-intensity area on T1-weighted image, hyper-intensity on T2-weighted image and remarkably-strong intensity on diffusion-weighted image. Gadolinium enhancement was partially seen in the tumor capsule. Bone density computed tomography (CT) and 3-dimensional CT using helical CT scan revealed the osteolytic range with destruction of the inner and outer table. From these findings, this tumor was diagnosed as diploic epidermoid cyst before surgery. The tumor was totally removed and underwent cranioplasty with a titanium plate. However, pathological examination confirmed dermoid cyst with existence of sebaceous gland in some cyst-walls. It was difficult to diagnose this case as dermoid tumor from radiological features before surgery.

T1-T2 Mismatch Sign as a Predictor of Ipsilateral Ischemic Change After Carotid Artery Stenting.

BACKGROUND: Magnetic resonance (MR)-plaque imaging reflects the characteristics of carotid plaque. We evaluated the relationship between MR-plaque images and ischemic change after carotid artery stenting (CAS). METHODS: MR-plaque images were acquired from patients with carotid artery stenosis before CAS treatment. We calculated the relative signal intensity of plaque components compared with that of the sternocleidomastoid muscle and evaluated the presence/absence of T1-T2 mismatch and match sign. We then assessed the appearance of new ischemic lesions after CAS on diffusion-weighted imaging (DWI). Factors associated with the appearance of a high-intensity lesion on DWI were retrospectively analyzed. RESULTS: A total of 64 patients with carotid artery stenoses treated with CAS were included in this study. In univariate analysis, T1-T2 mismatch sign was associated with the appearance of high-intensity lesions on DWI after CAS (odds ratio [OR], 12.00; 95% confidence interval [CI], 3.593-40.072; P < 0.0001), whereas T1-T2 match sign and high intensity on T2-weighted imaging were negatively associated (OR, 0.061, 95% CI, 0.007-0.502, P = 0.009 and OR, 0.085; 95% CI, 0.022-0.334, P = 0.0004, respectively). In multivariate logistic regression analysis, T1-T2 mismatch sign was independently associated with the appearance of a high-intensity lesion on DWI after CAS (OR, 16.695; 95% CI, 1.324-210.52; P = 0.0295). CONCLUSIONS: T1-T2 mismatch sign on MR-plaque imaging is significantly associated with the appearance of new ischemic lesions after CAS. T1-T2 mismatch sign may be useful in considering treatment strategies for carotid artery stenosis.

Mutated ZRSR2 and CUL3 accelerate clonal evolution and confer venetoclax resistance via RAS signaling pathway in blastic plasmacytoid dendritic cell neoplasm.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive subtype of myeloid malignancy characterized by skin, lymph node and central nervous system (CNS) involvement. Although various regimens are used, a standard therapeutic strategy for BPDCN has not been established. Recent studies revealed that BPDCN patients frequently have a mutation in ZRSR2, which is a minor spliceosome component. However, the association between the clinical features of BPDCN and ZRSR2 mutational status remains unknown. A 70-year-old man was referred to our hospital with skin rash and enlarged lymph nodes, as well as blasts in the peripheral blood. BPDCN was diagnosed based on the immunophenotype of the blasts derived from bone marrow. Whole exome sequencing revealed that BPDCN cells collected at diagnosis had mutations in ZRSR2, ZBTB33, CUL3, TET2 and NRAS. RNA sequencing analysis indicated that U12-type intron retention occurred in LZTR1, caused by ZRSR2 loss. After seven cycles of venetoclax combined with azacitidine therapy, BPDCN cells appeared in the peripheral blood and infiltrated the CNS. Two KRAS mutated clones appeared at BPDCN recurrence. These findings are important for understanding the pathogenesis of BPDCN, which will inform development of novel therapeutic strategies.

Successful allogeneic hematopoietic stem cell transplantation for myelodysplastic neoplasms complicated with secondary pulmonary alveolar proteinosis and Behçet's disease harboring GATA2 mutation.

Myelodysplastic neoplasms (MDS) are defined by cytopenia and morphologic dysplasia originating from clonal hematopoiesis. They are also frequently complicated with diseases caused by immune dysfunction, such as Behçet's disease (BD) and secondary pulmonary alveolar proteinosis (sPAP). MDS with both BD and sPAP is extremely rare, and their prognosis is poor. In addition, haploinsufficiency of the hematopoietic transcription factor gene GATA2 is recognized as a cause of familial MDS and is frequently complicated by sPAP. Herein, we report a case of MDS combined with both BD and sPAP in association with GATA2 deficiency in a Japanese woman. Because she developed progressive leukopenia and macrocytic anemia during BD treatment at the age of 61, she underwent a bone-marrow examination and was diagnosed with MDS. She subsequently developed sPAP. At the age of 63, she underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Since allo-HSCT, she has maintained complete remission of MDS as well as the symptoms of BD and sPAP. Furthermore, we performed whole exome sequencing and identified the GATA2 Ala164Thr germline mutation. These findings suggest that patients with MDS, BD and sPAP should be considered for early allo-HSCT.

[Astroblastoma with Rapid Cyst Expansion and Hemorrhage in an Adult: A Case Report].

Astroblastoma is an extremely rare primary brain tumor accounting for 0.45 to 2.8% of all neuroglial tumors and usually occurs in pediatrics and young adults. The natural history of astroblastoma still remains unknown. In the World Health Organization (WHO) classification of tumors of the central nervous system, astroblastoma is classified as other neuroepithelial tumors and standard treatment other than surgery has not been established. As molecular and genetic diagnosis becomes more important in the latest WHO classification of brain tumors, the development of therapeutic options based on the information of molecular genetics are expected. Here we report a case of astroblastoma in a 49-year-old male. Small tumor was discovered by coincidence during his check-up following traffic accident, but three months later, tumor bleeding with cystic enlargement resulted in disturbance of consciousness. Initial diagnosis of low grade astroblastoma with BRAFV600E mutation was made. After 1 year, local tumor recurrence was observed. The histological diagnosis at recurrence was high grade astroblastoma. We here, discuss about diagnosis, treatment and the possibility of usefulness of molecular genetic analysis for astroblastoma with some literature review. (Received 10 August, 2021; Accepted 15 December, 2021; Published 1 April, 2022).

Diffusion-weighted imaging-gadolinium enhancement mismatch sign in diffuse midline glioma.

BACKGROUND: Diffuse midline glioma (DMG), H3 K27M-mutant including diffuse intrinsic pontine glioma (DIPG) is a disease with dismal prognosis. We focused on diffusion-weighted imaging (DWI) and gadolinium enhanced T1WI (Gd), especially high intensity on DWI at non-enhanced lesion, i.e. DWI-Gd mismatch sign, to establish as an imaging biomarker of DMG patients. MATERIALS AND METHODS: Our institutional review board approved this retrospective study. Twenty-one patients diagnosed as DMG including DIPG at our institution between 2007 and 2020 were enrolled in this study. All patients underwent local radiotherapy of 54 Gy/30 fractions. We studied the relationship between imaging features including DWI-Gd mismatch sign and prognosis. RESULTS: DWI-Gd mismatch sign was found in 9 out of 21 DMG patients. Among different imaging characteristics, existence of high intensity on DWI (P = 0.0014), gadolinium enhancement (P = 0.00071) were the significant poor prognostic markers in DMG, which were consistent with the previous reports about DIPG. In our results, positive DWI-Gd mismatch sign was statistically strongest poor prognostic imaging biomarker, and patients with positive DWI-Gd mismatch sign had shorter OS compared to those with negative mismatch sign (9.9 months vs 18.6 months, P = 0.00062). DWI/Gd mismatch sign and intratumoral bleeding were more common in DMG at thalamus compared to DMG at pons/DIPG (P = 0.046 and P = 0.0017, respectively). CONCLUSIONS: DWI-Gd mismatch sign may be an imaging biomarker for poor prognosis in DMG. (E-1601).

[Craniopharyngioma Mimicking Chordoid Glioma].

Entirely intrinsic third ventricular craniopharyngiomas showed characteristics of a round/oval shaped tumor, with rare calcification and cyst formation, and pathologically squamous-papillary type with a positive BRAFV600E mutation. We report an extremely rare case of entirely intrinsic third ventricular craniopharyngioma, pathologically adamantiomatous but with BRAFV600E mutation genetically, developed in a 35-year-old female. It was oval-shaped, with no calcification or cyst, and showed homogeneous enhancement. As shown in this case, it was difficult to differentiate this pathology from chordoid glioma of third ventricle, and the difficulty of this differential diagnosis has not been well documented in previous studies. Our case further implied the importance of molecular diagnosis for subclassification of craniopharyngioma. The BRAFV600E-mutated craniopharyngioma could be the target for the development of treatment with preoperative BRAF-inhibitors. Therefore, differentiation between entirely intrinsic third ventricular craniopharyngiomas and chordoid glioma could be new issue. In this report, we discuss about the preoperative differential diagnosis from chordoid glioma and the literature review. (Received 12 August, 2021; Accepted 21 September, 2021; Published 1 February, 2022).

Intratumoral Hemorrhage After Endoscopic Third Ventriculostomy for Obstructive Hydrocephalus Caused by Brain Tumors.

BACKGROUND: Endoscopic third ventriculostomy (ETV) for obstructive hydrocephalus and endoscopic biopsy (EB) for intraventricular and paraventricular tumors are standard therapies because they are minimally invasive procedures. Although EB-associated hemorrhagic risk has been well documented, there have been only a few reports on hemorrhagic risk associated with ETV. We conducted a single-institution retrospective study on the incidence of hemorrhage secondary to EB and/or ETV. METHODS: We retrospectively reviewed patient characteristics, procedure, pathological findings, and complications including hemorrhage of 100 patients with intraventricular and paraventricular tumors who underwent EB and/or ETV at our institution from 2000 to 2020. RESULTS: EB/ETV combined surgery (combined group), EB-alone surgery (EB-alone group), and ETV-alone surgery (ETV-alone group) were performed in 44 (44%), 24 (24%), and 32 (32%) patients, respectively, and all procedures were successful. The rates of definitive and suggestive diagnoses in EB were 76.5% and 23.5%, respectively. Adverse events were observed in 6 patients. In the combined group, acute obstruction of the ETV stoma was observed in 1 patient and transient double vision was observed in 1 patient. Transient aqueductal stenosis/obstruction was observed in 2 patients in the EB-alone group. In the ETV-alone group, hemorrhage was observed in 2 patients; these patients developed intratumoral hemorrhage despite ETV-alone surgery. Subsequently, these 2 patients underwent tumor removal, and the histopathological diagnosis was atypical teratoid/rhabdoid tumor in both. CONCLUSIONS: For obstructive hydrocephalus with atypical teratoid/rhabdoid tumor, physicians must be aware of the risk of postoperative intratumoral hemorrhage after performing ETV.

Detecting non-germinomatous germ cell tumor component by arterial spin labeling perfusion-weighted MR imaging in central nervous system germ cell tumor.

PURPOSE: Differentiating between germinoma and non-germinomatous germ cell tumor (NGGCT) is important because sensitivity to chemotherapy and/or radiotherapy is quite different between these two subgroups. In this study, we evaluated whether the arterial spin labeling (ASL) based perfusion-weighted imaging (PWI) could provide additional information for the differential diagnosis between germinoma and NGGCT. METHOD: Between 2011 and 2018, 20 patients with central nervous system (CNS) germ cell tumor (GCT) who underwent preoperative MR imaging including ASL-PWI were enrolled in this study. Relative tumor blood flow (rTBF) was evaluated on ASL-PWI by manually placing regions of interest at gadolinium enhanced part of the tumors and normal subcortical white matter. Presence of intratumoral T1 hyperintense foci and apparent diffusion coefficient (ADC) were also evaluated. The final diagnosis was made by the combination of tumor markers and the histological diagnosis. RESULTS: Among 20 patients of CNS-GCT, 11 were diagnosed as germinoma and 9 were diagnosed as NGGCT. In the germinoma subgroup, the rTBF ranged from 0.90 to 1.71 (mean 1.21, median 1.09), while it ranged from 1.14 to 5.75 (mean 3.91, median 3.31) in NGGCT subgroup. The receiver operating characteristic (ROC) curve showed that calculating rTBF is useful for differentiating between germinoma and NGGCT (area under the curve (AUC) 0.929, P = 0.0012) compared to intratumoral T1 hyperintense foci (AUC 0.788, P = 0.0304) and ADC (AUC 0.919, P = 0.0016). CONCLUSIONS: High rTBF obtained by ASL-PWI implied the presence of NGGCT component. This information might help in deciding the chemotherapy/radiotherapy intensity.

Radiology Profile as a Potential Instrument to Differentiate Between Posterior Fossa Ependymoma (PF-EPN) Group A and B.

OBJECTIVE: Posterior fossa ependymoma (PF-EPN) was categorized into PF-EPN-A and PF-EPN-B subgroups based on the DNA methylation profiling. PF-EPN-A was reported to have poorer prognosis compared with PF-EPN-B. In this study, we particularly evaluated preoperative imaging to distinguish PF-EPN-A from PF-EPN-B. METHODS: Sixteen cases of PF-EPN were treated in our institution from 1999 to 2018. The patients were divided into PF-EPN-A and PF-EPN-B groups based on H3K27me3 immunostaining positivity. We evaluated progression-free survival, overall survival, as well as preoperative magnetic resonance imaging and computed tomography scan images in both groups. Based on T1WI and Gd-T1WI magnetic resonance images, the tumor contrast rate was determined from dividing the volume of gadolinium enhanced tumor by the overall tumor volume. RESULTS: Nine cases (4 male, 5 female) were grouped as PF-EPN-A, and 7 (4 male, 3 female) as PF-EPN-B. The median age of PF-EPN-A and PF-EPN-B were 4 and 43 years old, respectively. In the PF-EPN-A group, the progression-free survival median value was 32.6 months, and the overall survival median was 96.9 months. In contrast, PFS in PF-EPN-B did not reach a median value (P < 0.05) and all the patients were alive (P < 0.05) at the end of the study. With imaging, tumor contrast rate in PF-EPN-B was more than 50% and significantly different from PF-EPN-A (P = 0.0294). Calcification was mainly observed in PF-EPN-A, whereas cystic formation was only seen in PF-EPN-B. CONCLUSIONS: Contrast rate less than 50%, based on the magnetic resonance images, was characteristic in the PF-EPN-A group. Comparatively, cystic component and absence of calcification were more characteristic in the PF-EPN-B group.

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.

T2-FLAIR mismatch sign in dysembryoplasticneuroepithelial tumor.

PURPOSE: T2-FLAIR mismatch sign was reported as specific imaging marker in non-enhancing diffuse astrocytoma, IDH-mutant & 1p/19q non-codeleted. However, most of the previous studies for T2-FLAIR mismatch sign were confirmed only among lower grade glioma. The aim of this study is to assess the T2-FLAIR mismatch sign in dysembryoplastic neuroepithelial tumor (DNET) and unveil the exception rules of the sign. METHOD: Eleven patients with histopathologically confirmed DNET were included in this study. The MR images were evaluated by 2 independent reviewers to assess (i) the presence or absence of T2-FLAIR mismatch sign and (ii) the presence or absence of gadolinium enhancement. CT was also performed to evaluate calcification and localized thinning of the skull bone. Inter-reviewer agreement with Cohen's kappa (κ) was calculated. RESULTS: The T2-FLAIR mismatch sign was present in 8 cases (72.7 %) and absent in 3 cases (27.3 %). None of them showed contrast enhancement on initial MR images. The inter-reviewer agreement for T2-FLAIR mismatch and CT characteristics was excellent (κ = 1.00). All of the DNET without T2-FLAIR mismatch presented with calcification on CT. All of the DNET adjacent to skull vault (5 cases) presented with localized bone thinning overlying the tumor. CONCLUSIONS: The T2-FLAIR mismatch sign was observed in more than half of the DNET and the sign is not specific for diffuse astrocytoma, IDH-mutant & 1p19q non-codeleted. The localized skull bone thinning overlying the tumor might help for diagnosis of DNET in some cases.