Answer for BIR CoW 20 Feb 2022
Vertebral artery aneurysm
Findings
Evidence of T1 and T2 predominantly hypointense lesion with whorled appearance seems to arise from left V4 segment of vertebral artery measuring measuring 1.4(transverse) x 1.6(antero-posterior) x 2.3(cranio caudal) cms showing gradient blooming with no diffusion restriction . The lesion shows eccentric T1 and T2 hyperintensity with diffusion restriction – reflecting late subacute thrombosis . MR Angiogram reveals patent lumen measures 7.4 mm(antero-posterior) x 7.6 mm( transverse ) . Left transverse sinus, sigmoid sinus hypoplastic. Impression :Features suggestive of thrombosed saccular aneurysm V4 segment of left vertebral artery.
Discussion
Imaging features of aneurysms in Mri are as follows : CT Findings. Very small unruptured Saccular Aneurysms may be invisible on standard NECT scans. Larger lesions appear as well-delineated masses that are slightly hyperdense to brain . Rim or mural calcification may be present. Acutely ruptured SAs present with aSAH, which is often the dominant imaging feature and frequently obscures the "culprit" aneurysm. Occasionally, an SA appears as a well-delineated, relatively hypodense filling defect within a pool of hyperdense subarachnoid blood. A partially or completely thrombosed SA is typically hyperdense compared with the adjacent brain on NECT scans. Patent SAs show strong, uniform enhancement of the aneurysm lumen. A partially thrombosed SA shows enhancement of the residual lumen. Completely thrombosed SAs do not enhance, although longstanding lesions may demonstrate rim enhancement secondary to reactive inflammatory changes. MR Findings. MR findings vary with pulse sequence, flow dynamics, and the presence as well as the age of associated hemorrhage (either in the subarachnoid cisterns or within the aneurysm itself). About half of all patent SAs demonstrate "flow voids" on T1- and T2WI . The other half exhibit heterogeneous signal intensity secondary to slow or turbulent flow, saturation effects, and phase dispersion. Propagation of pulsation artifacts in the phase-encoding direction is common. FLAIR scans may show hyperintensity in the subarachnoid cisterns secondary to aSAH. If the aneurysm is partially or completely thrombosed, laminated clot with differing signal intensities is often present . "Blooming" on susceptibility-weighted images (GRE, SWI) is common. Contrast-enhanced scans may show T1 shortening in intraaneurysmal slow-flow areas. Highresolution contrast-enhanced MR may demonstrate inflammatory changes in the aneurysm wall and adjacent brain.
References
1 Osborn's Brain imaging , pathology and anatomy by Anne G Osborn Section2 Chapter 6 page number 141 . 2 Backes D et al: ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms. Neurology. 88(17):1600-1606, 2017 3Björkman J et al: Irregular shape identifies ruptured intracranial aneurysm in subarachnoid hemorrhage patients with multiple aneurysms. Stroke. ePub, 2017 Choi HH et al: Growth of untreated unruptured small-sized aneurysms (7mm): incidence and related factors. Clin Neuroradiol. ePub, 2017 4Kleinloog R et al: Risk factors for intracranial aneurysm rupture: a systematic review. Neurosurgery. ePub, 2017 5Backes D et al: Patient- and aneurysm-specific risk factors for intracranial aneurysm growth: systematic review and metaanalysis. Stroke. 47(4):951-7, 2016 6Blankena R et al: Thinner regions of intracranial aneurysm wall correlate with regions of higher wall shear stress: a 7T MRI study. AJNR Am J Neuroradiol. 37(7):1310-7, 2016 7Mayer TE et al: The unruptured intracranial aneurysm treatment score: a multidisciplinary consensus. Neurology. 86(8):792-3, 2016
Findings
Evidence of T1 and T2 predominantly hypointense lesion with whorled appearance seems to arise from left V4 segment of vertebral artery measuring measuring 1.4(transverse) x 1.6(antero-posterior) x 2.3(cranio caudal) cms showing gradient blooming with no diffusion restriction . The lesion shows eccentric T1 and T2 hyperintensity with diffusion restriction – reflecting late subacute thrombosis . MR Angiogram reveals patent lumen measures 7.4 mm(antero-posterior) x 7.6 mm( transverse ) . Left transverse sinus, sigmoid sinus hypoplastic. Impression :Features suggestive of thrombosed saccular aneurysm V4 segment of left vertebral artery.
Discussion
Imaging features of aneurysms in Mri are as follows : CT Findings. Very small unruptured Saccular Aneurysms may be invisible on standard NECT scans. Larger lesions appear as well-delineated masses that are slightly hyperdense to brain . Rim or mural calcification may be present. Acutely ruptured SAs present with aSAH, which is often the dominant imaging feature and frequently obscures the "culprit" aneurysm. Occasionally, an SA appears as a well-delineated, relatively hypodense filling defect within a pool of hyperdense subarachnoid blood. A partially or completely thrombosed SA is typically hyperdense compared with the adjacent brain on NECT scans. Patent SAs show strong, uniform enhancement of the aneurysm lumen. A partially thrombosed SA shows enhancement of the residual lumen. Completely thrombosed SAs do not enhance, although longstanding lesions may demonstrate rim enhancement secondary to reactive inflammatory changes. MR Findings. MR findings vary with pulse sequence, flow dynamics, and the presence as well as the age of associated hemorrhage (either in the subarachnoid cisterns or within the aneurysm itself). About half of all patent SAs demonstrate "flow voids" on T1- and T2WI . The other half exhibit heterogeneous signal intensity secondary to slow or turbulent flow, saturation effects, and phase dispersion. Propagation of pulsation artifacts in the phase-encoding direction is common. FLAIR scans may show hyperintensity in the subarachnoid cisterns secondary to aSAH. If the aneurysm is partially or completely thrombosed, laminated clot with differing signal intensities is often present . "Blooming" on susceptibility-weighted images (GRE, SWI) is common. Contrast-enhanced scans may show T1 shortening in intraaneurysmal slow-flow areas. Highresolution contrast-enhanced MR may demonstrate inflammatory changes in the aneurysm wall and adjacent brain.
References
1 Osborn's Brain imaging , pathology and anatomy by Anne G Osborn Section2 Chapter 6 page number 141 . 2 Backes D et al: ELAPSS score for prediction of risk of growth of unruptured intracranial aneurysms. Neurology. 88(17):1600-1606, 2017 3Björkman J et al: Irregular shape identifies ruptured intracranial aneurysm in subarachnoid hemorrhage patients with multiple aneurysms. Stroke. ePub, 2017 Choi HH et al: Growth of untreated unruptured small-sized aneurysms (7mm): incidence and related factors. Clin Neuroradiol. ePub, 2017 4Kleinloog R et al: Risk factors for intracranial aneurysm rupture: a systematic review. Neurosurgery. ePub, 2017 5Backes D et al: Patient- and aneurysm-specific risk factors for intracranial aneurysm growth: systematic review and metaanalysis. Stroke. 47(4):951-7, 2016 6Blankena R et al: Thinner regions of intracranial aneurysm wall correlate with regions of higher wall shear stress: a 7T MRI study. AJNR Am J Neuroradiol. 37(7):1310-7, 2016 7Mayer TE et al: The unruptured intracranial aneurysm treatment score: a multidisciplinary consensus. Neurology. 86(8):792-3, 2016
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!