Blind Spots in Spine Imaging

Mougnyan Cox, MD; Linda Bagley, MD; Joseph Philip, MD; Joshua Thatcher, MD; Ike Thacker, MD; Conan Gomez; Kennith Layton, MD

Disclosures

Appl Radiol. 2022;51(2):15-23. 

In This Article

Vascular Abnormalities

Vascular abnormalities can be a significant source of morbidity and mortality; some can be mitigated or even prevented by early detection and treatment. One of the most common serious abnormalities on a cervical spine study is dissection of the vertebral artery. It is not uncommon for patients with a vertebral artery dissection to present with neck pain, a frequent complaint in patients with musculoskeletal disorders of the neck. The dissection may be pre-existing and exacerbated by chiropractic manipulation,[10] or it potentially may be the inciting event in patients with vascular fragility syndromes such as fibromuscular dysplasia.

Abnormal vertebral artery flow void on MRI can be a clue to, but not diagnostic of, a vertebral artery dissection (Figure 3), as the artery may be congenitally small or chronically occluded. Posterior circulation infarctions seen at the edge of the field of view on sagittal T2 images of the cervical spine increase the likelihood that the vertebral artery abnormality is real. Protocols with T1 images may also show hyperintense T1 signal from subacute intraluminal thrombus. Vertebral artery dissections are an important cause of neck pain, particularly in younger patients.[11] Early treatment with antithrombotic therapy may promote healing and prevent thromboembolism and posterior circulation ischemia/infarction. Anatomic variants that are not inherently dangerous may become important to recognize prior to surgery or other intervention that may place the artery at risk for injury (Figure 4).

Figure 3.

Middle-aged patient with neck pain. Axial T2 image (A) shows loss of the expected right vertebral artery flow void with central T2 hyperintensity in the larger of the two lumens (arrow). Subsequent computed tomography angiogram of the neck (B) confirms a right vertebral artery dissection and near-occlusion of the larger lumen (arrow).

Figure 4.

Older patient with neck pain. Sagittal T2 image (A) shows spondylosis with marked canal stenosis, spinal cord impingement, and spinal cord signal abnormality (arrow). Axial noncontrast CT (B) demonstrates medial deviation of the dominant left vertebral artery at the level of anticipated decompression surgery with corresponding enlarged vascular groove (arrow). Calling attention to this preoperatively may reduce the chance of vertebral artery injury. Catheter angiography (C) confirms focal tortuosity of the left vertebral artery (arrow).

Abnormalities of the aorta are a primary concern when imaging the thoracolumbar spine. Mycotic aneurysms and thoracic aorta dissections may coexist where destructive discitis-osteomyelitis dominates clinical and imaging findings (Figure 5). Abdominal aortic and aorto-iliac aneurysms and stenoses are not uncommon in patients over age 65, particularly those with a smoking history, and they may be first discovered at spine imaging.[11] Aorto-iliac occlusion or insufficiency may also present with lower-extremity weakness and urinary incontinence and/or retention, clinically mimicking a compressive myelopathy (Figure 6). Owing to the substantial morbidity associated with undiagnosed abnormalities of the vessel, the thoracoabdominal aorta should be included on the checklist of all spine studies and considered equal in importance to any spondylosis (Figure 7).

Figure 5.

Middle-aged patient with discitis-osteomyelitis and an infected abdominal aortic aneurysm. Sagittal T1 image (A) shows abnormal marrow signal and destruction of the L3-L4 disc space and adjoining endplates (arrow), with a focal bulge of the abdominal aorta immediately adjacent to the area of signal abnormality. Contrast-enhanced CT of the abdomen and pelvis (B) showed a focal irregular abdominal aortic aneurysm with a 'draped' appearance of the bulging region (arrow).

Figure 6.

Elderly patient with back pain and lower-extremity weakness. Axial T2 image (A) of the lumbar spine shows loss of the expected flow void in the aorta (arrow). Subsequent CT angiogram of the abdomen and pelvis (B) confirms aortic occlusion (arrow).

Figure 7.

Contrast-enhanced CT of the lumbar spine performed emergently for back pain and concern for cauda equina syndrome shows infiltrative soft tissue encasing the celiac axis and its branches, with invasion of the adjacent left adrenal gland (arrow). Subsequent diagnosis was pancreatic malignancy.

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