Differentiation of hemangioblastoma from brain metastasis using MR amide proton transfer imaging

Amide proton transfer weighted imaging in pediatric neuro-oncology: initial experience

Amide proton transfer weighted (APTw) imaging enables in vivo assessment of tissue-bound mobile proteins and peptides through the detection of chemical exchange saturation transfer. Promising applications of APTw imaging have been shown in adult brain tumors. As pediatric brain tumors differ from their adult counterparts, we investigate the radiological appearance of pediatric brain tumors on APTw imaging. APTw imaging was conducted at 3 T. APTw maps were calculated using magnetization transfer ratio asymmetry at 3.5 ppm. First, the repeatability of APTw imaging was assessed in a phantom and in five healthy volunteers by calculating the within-subject coefficient of variation (wCV). APTw images of pediatric brain tumor patients were analyzed retrospectively. APTw levels were compared between solid tumor tissue and normal-appearing white matter (NAWM) and between pediatric high-grade glioma (pHGG) and pediatric low-grade glioma (pLGG) using t-tests. APTw maps were repeatable in supratentorial and infratentorial brain regions (wCV ranged from 11% to 39%), except those from the pontine region (wCV between 39% and 50%). APTw images of 23 children with brain tumor were analyzed (mean age 12 years ± 5, 12 male). Significantly higher APTw values are present in tumor compared with NAWM for both pHGG and pLGG (p < 0.05). APTw values were higher in pLGG subtype pilocytic astrocytoma compared with other pLGG subtypes (p < 0.05). Non-invasive characterization of pediatric brain tumor biology with APTw imaging could aid the radiologist in clinical decision-making.

Cerebellar Metastasis Manifesting as a Cyst with Mural Nodule(s): Differentiating It From Hemangioblastoma on MRI

BACKGROUND

A cyst with mural nodule(s) (CMN) is a rare imaging finding of cerebellar metastasis (CMET). It is a great challenge to differentiate it from cerebellar hemangioblastoma (CHB). In the present study, we explore the differences in the magnetic resonance imaging (MRI) characteristics of the 2 tumors.

METHODS

Patients with pathologically confirmed CMET or CHB at our hospital from July 2009 to September 2021 were enrolled in the present study. All the patients underwent conventional head MRI (before and after contrast administration) before surgery and had ≥1 lesion in the cerebellum that presented as CMN on MRI. The clinical and MRI features were compared between the 2 groups.

RESULTS

A total of 33 patients (10 with CMET and 23 with CHB) met the study criteria. The CMET patients were significantly older than were the CHB patients (median age, 59.5 years vs. 37 years; P = 0.002). Compared with the CHB group, the CMET group showed significantly higher occurrence rates of multiple mural nodules (72.7% vs. 8.7%), lack of vascular flow voids (100% vs. 65.2%), isointense or hypointense mural nodules on fluid-attenuated inversion recovery imaging (100.0% vs. 22.7%), restricted diffusion of mural nodules (22.2% vs. 0.0%), mildly enhanced mural nodules (90.9% vs. 4.3%), and a ring-enhanced pattern of the cyst wall (100% vs. 8.7%; P < 0.05 for all).

CONCLUSIONS

When CMN is detected in the cerebellum on MRI, older age, multiple mural nodules, absence of vascular flow voids, isointense or hypointense mural nodule on fluid-attenuated inversion recovery sequence, restricted diffusion of the mural nodule, mildly enhanced mural nodules, and a ring-enhanced pattern of the cyst wall are the clinical and imaging features that strongly indicate the likelihood of metastasis, rather than CHB.