Clinician-to-Clinician Update Clinician-to-Clinician Update

MRI-Guided Biopsy and Laser Ablation of a Difficult-to-Access Brain Tumor

February 2018

— Figure 1. Magnetic resonance image of a tumor in the right para-median cerebellum of a 16-year-old boy.

Contributed by Clark C. Chen, MD, PhD

Patients with neurofibromatosis 1 (NF1) are at risk of developing benign and sometimes malignant tumors, including gliomas and other brain tumors. Location of brain tumors can render biopsy difficult and surgical removal prohibitive. Use of real-time magnetic resonance imaging (MRI) to guide biopsies and facilitate laser ablation as intervention with durable response,1,2 as illustrated in this case.


A 16-year-old male patient previously diagnosed with NF1 sought evaluation for a brain tumor. The tumor was a 1.0 x 0.9 x 0.8 cm lesion located in the right para-median cerebellum. The lesion showed contrast enhancement, with minimal surrounding FLAIR signal. The lesion abutted the fourth ventricle but did not exert mass effect on the fourth ventricle (Figure 1).



Because the patient was asymptomatic, this lesion was closely followed with serial MRIs. Enlargement of the lesion was observed on two sequential MRIs. The last MRI showed that the lesion had begun to compress the fourth ventricle. Because of the demonstrated serial radiographic progression and the concern for eventual hydrocephalus, surgical intervention was considered. Due to the deep location of the lesion, surgical resection was not possible without significant morbidity. Instead, the patient underwent a stereotactic biopsy of the lesion. The biopsy yielded nondiagnostic tissues.


The patient was then referred to the University. The patient underwent another MRI, which showed evidence suggesting that the previous biopsy was performed in a region adjacent to the lesion. After case review by multidisciplinary team, which included specialists from neuro-oncology, radiation oncology, neurosurgery and others, repeat biopsy was recommended. The patient underwent an MRI-guided biopsy, a procedure performed within a diagnostic MRI as to enable confirmation of the biopsy site in real time. Pathologic examination of the specimen secured from this biopsy revealed pathology findings consistent with pilocytic astrocytoma.

As a result of these findings, the lesion was ablated with laser-induced thermal coagulation in the same setting. The patient emerged from the procedure without neurologic deficit and was discharged the next day. The final pathologic analysis confirmed the diagnosis of pilocytic astrocytoma. At the 2-year follow-up MRI, the patient demonstrated no evidence of tumor re-growth.


  1. Scheer JK, Hamelin T, Chang L, Lemkull B, Carter BS, Chen CC. Real-time magnetic resonance imaging-guided biopsy using SmartFrame® stereotaxis in the setting of a conventional diagnostic magnetic resonance imaging suite. Oper Neurosurg. (Hagerstown) 2017;13(3):329-337.
  2. Rennert RC, Carroll KT, Mir Amaan A, Hamelin T, Change L, Lemkull BP, CC Chen. Safety of stereotactic laser ablations performed as treatment for glioblastomas in a conventional magnetic resonance imaging suite. Neurosurg Focus. 2016;41(4):E11
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