Modern brain tumor imaging

Abstract

The imaging and clinical management of patients with brain tumor continue to evolve over time and now heavily rely on physiologic imaging in addition to high-resolution structural imaging. Imaging remains a powerful noninvasive tool to positively impact the management of patients with brain tumor. This article provides an overview of the current state-of-the art clinical brain tumor imaging. In this review, we discuss general magnetic resonance (MR) imaging methods and their application to the diagnosis of, treatment planning and navigation, and disease monitoring in patients with brain tumor. We review the strengths, limitations, and pitfalls of structural imaging, diffusion-weighted imaging techniques, MR spectroscopy, perfusion imaging, positron emission tomography/MR, and functional imaging. Overall this review provides a basis for understudying the role of modern imaging in the care of brain tumor patients.

Keywords: Brain neoplasms; Glioblastoma; Glioma; Magnetic resonance imaging; Neuroimaging.

Fig. 1. 57-year-old male patient who presented with loss of consciousness and seizure and who initially had a non-contrast CT (A) performed that demonstrated a partially calcified mass in the left frontal lobe. Preoperative MR images include axial T2 FLAIR (B), axial T1 post-contrast (C), axial SWI (D), coronal T2 FLAIR (E), axial DWI (F), axial ADC map (G), and DTI tractography of the left corticospinal tract superimposed on axial T2 (H). This T2/FLAIR hyperintense (B, E, and H), non-enhancing mass (C), with internal calcifications visible on CT (A) and as susceptibility on SWI (D) was a grade II oligoastrocytoma (TP53 mutation negative, IDH1 mutation positive, 1p19q co-deletion positive). A gross total resection was performed and the patient remains alive. ADC, apparent diffusion coefficient; CT, computed tomography; DTI, diffusion-tensor imaging; DWI, diffusion weighted imaging; FLAIR, fluid attenuated inversion recovery; MR, magnetic resonance; SWI, susceptibility weighted imaging.

Fig. 2. 78-year-old female patient with a glioblastoma who presented with gait instability, dizziness, and dysarthria for 6-8 weeks. Preoperative MR images include axial T1 post-contrast (A), coronal T1 post-contrast (B), axial T2 FLAIR (C), axial DWI (D), axial ADC map (E), axial DSC perfusion (F), and corresponding perfusion curve (G). Post-contrast T1 images (A and B) demonstrate irregular rim enhancement and central necrosis of this tumor centered in the right frontal lobe. Surrounding the enhancing component is T2 FLAIR hyperintensity (C) which is likely infiltrative cellular edema. The lesion demonstrates restricted diffusion with low ADC values (D and E) and increased relative cerebral blood volume compared to the contralateral side (F and G) with return to baseline of the perfusion curve consistent with a primary glial tumor. ADC, apparent diffusion coefficient; DSC, dynamic susceptibility contrast-enhanced; DWI, diffusion weighted imaging; FLAIR, fluid attenuated inversion recovery; MRI, magnetic resonance image.

Fig. 3. 33-year-old female patient with a left insular glioblastoma (19q deletion, 1p intact, IDH1 mutation, PTEN and EGFR mutation negative) who presented with syncope and seizure. Preoperative MR images include axial T1 post-contrast (A), axial T2 FLAIR (B), axial DWI (C), axial ADC map (D), spectroscopy with choline to NAA ratio overlay on axial T1 post-contrast (E), corresponding spectroscopy and choline to NAA ratios (F), axial DSC perfusion (G), corresponding perfusion curve (H), and DTI tractography of the left corticospinal tract (I) and left arcuate fasciculus (J) superimposed on axial T2. Post-contrast T1 image (A) demonstrate irregular patchy partial enhancement within the tumor. T2 FLAIR (B) shows the extent of non-enhancing T2 FLAIR hyperintense tumor. The lesion demonstrates areas of restricted diffusion with low ADC values (C and D) and increased relative cerebral blood volume compared to the contralateral side (G and H) with return to baseline of the perfusion curve consistent with a primary glial tumor. Spectroscopy (E and F) demonstrates elevated choline relative to NAA, consistent with a glioma. ADC, apparent diffusion coefficient; DSC, dynamic susceptibility contrast-enhanced; DTI, diffusion tensor imaging; DWI, diffusion weighted imaging; EGFR, epidermal growth factor receptor; FLAIR, fluid attenuated inversion recovery; IDH, isocitrate dehydrogenase; MRI, magnetic resonance image; NAA, N-acetylaspartate; PTEN, phosphatase and tensin homolog.

Fig. 4. 49-year-old female patient with two months of headaches and falls and a remote history of right lung lobectomy for reported benign tumor with MR imaging demonstrating a solitary mass in the right cingulate gyrus which upon resection was metastatic adenocarcinoma (ultimately metastatic non-small cell lung cancer). Preoperative MR images include axial T1 post-contrast (A), axial T2 FLAIR (B), axial DSC perfusion (C), and corresponding perfusion curve (D). Post-contrast T1 image (A) demonstrates the solitary enhancing mass. T2 FLAIR (B) shows the large amount of peri-tumoral vasogenic edema. DSC perfusion (C and D) shows elevated cerebral blood volume relative to the contralateral side without return of the curve to baseline, suggesting a solitary metastasis as opposed to a glioma. DSC, dynamic susceptibility contrast-enhanced; FLAIR, fluid attenuated inversion recovery; MRI, magnetic resonance image.

Fig. 5. 64-year-old male patient who presented with expressive aphasia and dysarthria and ultimately was diagnosed with glioblastoma (IDH1 non-mutated, PTEN deleted, EGFR amplification negative) and underwent a subtotal resection. Preoperative MR images include axial T1 post-contrast (A) demonstrating a peripherally enhancing mass, and task based BOLD-fMRI functional maps superimposed on anatomic images (B-F) (courtesy of Pratik Mukherjee, MD, PhD). A tongue movement paradigm (B and C) demonstrated bilateral supra-sylvian peri-rolandic activation, which on the left abuts the posterior aspect of the tumor anteriorly as demonstrated on axial (B) and sagittal (C) images. A covert visual verb generation paradigm localized expressive language function to the left (D and E), which was anterior to the tumor but approached the anterior inferior aspect of the tumor (not pictured). A passive listening paradigm localized receptive language function to the left (F), separate from the tumor. EGFR, epidermal growth factor receptor; fMRI, functional magnetic resonance image; IDH, isocitrate dehydrogenase; MRI, magnetic resonance image; PTEN, phosphatase and tensin homolog.

Fig. 6. Single modality FMISO PET/MR imaging in a 65-year-old man with recurrent left temporal lobe WHO grade III anaplastic astrocytoma. Simultaneously obtained, axial FMISO PET (A), post contrast T1-weighted (B), and fused T1 post contrast FMISO (C) PET/MR demonstrates recurrence of disease evidenced by contrast enhancing focus bordering the posterior margin of an anterior left temporal lobe resection cavity. This region demonstrates increased FMISO uptake. FMISO, ¹⁸F-flouromisoidazole; MR, magnetic resonance; PET, positron emission tomography; WHO, World Health Organization.