There is a growing awareness that invasive procedures involving needles, such as biopsy, contrast injection and sedation, can have potentially dangerous side effects. In particular, there are concerns regarding the use of gadolinium-based contrast media in patients with compromised renal functions. The availability of sequences such as 3D ASL, a non-contrast, wholebrain sequence providing quantitative perfusion assessment for evaluating tumors and neurodegenerative diseases, assessing stroke or other cerebrovascular disease, and identifying structural vascular problems is an invaluable sequence in our facility.
Combining 3D ASL with PROBE spectroscopy in oncology patients provides the ability to confidently characterize lesions non-invasively and needle-free without contrast injection.
Patient history
A 55-year-old male with recently diagnosed adrenal cancer and some neurological concerns was referred for an MR brain exam to detect for secondary or metastatic lesions. The patient was also diagnosed with poor renal function, which was a pathology resulting from the adrenal cancer, and had not yet started dialysis treatment. As a consequence, MR contrast media could not be administered.
Technique
Typically, a post-contrast 3D T1 FSPGR acquisition is utilized to obtain information on contrast agent uptake for active lesions and non-contrast uptake for necrotic lesions. Since a contrast agent could not be used in this patient, 3D ASL and PROBE spectroscopy were the key sequences to provide morphological and vascular imaging data, and help differentiate the patient’s brain tumors.
Figure 1.
A lesion is depicted on the left temporal lobe, measuring 42 x 30 mm from its long axes, (yellow arrows) and another lesion is shown on the right temporal lobe and measuring 10 mm from its long axis (red arrows). (A, B) Axial T2 FSE, 4 mm slices acquired in 3:07 min. and (C) map from 3D ASL, 4 mm slices, PLD 2525 ms, 5:10 min.
Figure 2.
T2 FSE and the CBF map from 3D ASL help detect the posteroexternal hyperperfused area. (A, B) Coronal T2 FSE, 4:1 mm slices acquired in 3:10 min. and (C) fused coronal T2 FSE and MPR coronal CBF map from 3D ASL.
Results
With 2D FSE, two lesions were depicted, one located on the left temporal lobe and measuring 42 × 30 mm from its long axes, and the second lesion located on the right temporal lobe and measuring 10 mm from its long axis.
The 3D ASL sequence showed a posteroexternal hyperperfused area on the Cerebral Blood Flow (CBF) parametric map.
The second lesion is widely necrosed with no aspect on CBF map.
The lesion located on the left temporal lobe is surrounded with fluid, hypointense in T1 and hyperintense in T2, T2 FLAIR and T2∗. A PROBE spectroscopy study of this fluid area shows a peak of lipids confirming necrotic component.
These lesions are surrounded with oedemic areas hyperintense in T2 and T2 FLAIR and are at the origin of a moderated mass effect on the left temporal horn and left lateral ventricle.
The lesion located on the left temporal lobe measuring 42 × 30 mm shows a compatible profile with a secondary or metastatic lesion (double component with tissue and necrosis).
Figure 3.
Using spectroscopy PROBE SV, it is possible to identify the posteroexternal hyperperfused area with a necrotic component. (A) Fused axial T2 FSE and monovoxel spectroscopy PROBE SV and (B) fused CBF map from axial 3D ASL and monovoxel spectroscopy PROBE SV, TE=35 ms, 12 x 12 x 12 mm (1.728 cm3), 7 min. (C) Monovoxel spectroscopy PROBE SV showing spectrum of diseased region with peak of lipids.
Figure 4.
Area of fluid is hypointense in (A) T1 FSE images and hyperintense in (B-D) T2* EPI, T2 FLAIR and T2 FSE.
Figure 5.
Fluid area with lipids peak confirms necrotic component. (A) Fused axial T2 FSE and multivoxel spectroscopy PROBE SI, TE=144 ms; (B) fused axial T2 FSE and lactates and lipids metabolites map; and (C) multivoxel spectroscopy PROBE SI demonstrating comparison between spectrum of perilesional region (yellow line) and VS spectrum of contralateral healthy region (blue line).
Figure 6.
Images depict posteroexternal hyperperfused area and necrotic fluid area. (A) Fused CBF map from 3D ASL and lactates and lipids metabolites map and (B) fused axial T2 FSE and CBF map from 3D ASL and lactates and lipids metabolites map. Note: 6B is for presentation purposes only, not generated by post-processing software.
Discussion
The diagnostic approach and therapeutic pathway for this patient is possible due to the use of 3D ASL and PROBE spectroscopy, which confirmed the tumoral nature of a lesion. First, the hyperperfusion aspect on the CBF map from the 3D ASL sequence was consistent with a tumoral neo- angiogenesis of the lesion located on the left temporal lobe. Second, the lipids peak on PROBE spectroscopy confirmed the extended necrotic component within this same lesion.
