-By Travis Snyder, DO
Distinguishing acute trauma from pre-existing degenerative changes (changes of aging) and other pathologic processes during medical imaging is essential for patient care and management, yet this is often challenging for both the treating physician and the radiologist. Imaging terminology and options, such as MRI pulse sequences can be confusing for physicians and non-physicians alike. Understanding of these concepts is surely essential for attorneys managing medical legal cases.
Understanding the utility of the various modalities available in diagnostic imaging is important. Fractures in the spine or extremities can occasionally be subtle or not visualized on plain film (x-ray) and if there is high clinical concern, MRI is recommended. Extremity x-rays for fractures should ideally include standard 3 views. Ligament and tendon injuries are most often not seen on x-ray, although indirect signs may be present. MRI is the exam of choice to asses these and other soft tissue injuries. CT is excellent for assessing bony pathology such as fractures, particularly rib fractures, but is more limited in assessing the soft tissues. Intravenous contrast may be administered in cross sectional studies (MRI or CT), but other than to assess for abdominal organ or vascular injury, contrast is of limited value in evaluating acute or subacute injuries and is generally reserved to characterize or diagnose nontraumatic conditions such as infection or neoplasm or postsurgical spinal evaluation. A MRI arthrogram is a procedure where MRI sensitive contrast and water are injected into the joint under fluoroscopic imaging guidance by a radiologist and then scanned using MRI. This exam is typically ordered to assess the labrum (an important stabilizing thin but sturdy circumferential soft tissue structure peripheral and superficial to the cartilage), in either in the shoulder or hip where intraarticular contrast (Arthrogram) offers increased detection rate for labral tears1. Ultrasound may be of benefit to assess for traumatic ventral abdominal or inguinal hernia.
In the spine, straightening, and particularly reversal, of the normal cervical and lumbar lordotic (posterior concave arching as seen on sagittal/lateral view) curvatures, can be associated with muscle spasm and pain in the proper clinical setting. Anterior subluxation (anterolisthesis) and posterior subluxation (retrolisthesis) of a vertebral body compared to the one below may indicate underlying ligamentous injury, particularly in younger patients. Translation (movement) of one vertebral body on another as seen on sagittal (lateral or side view) imaging during flexion and extension x-ray/MRI or dynamic flexion/extension video fluoroscopy is a concerning finding. Translation can be indicative of instability with underlying ligamentous injury and has prognostic value in determining disability2. Assessment of ligamentous injury is best seen on sagittal STIR imaging (a dedicated fluid sensitive MRI sequence). Subtle injuries may be better identified on the more advanced 3.0 Tesla magnet (rather than a 1.0 or 1.5 Tesla system).
Intervertebral discs are present in-between the vertebral bodies and best evaluated on MRI. Morphology of disc pathology is important; disc protrusions and extrusions are more likely to be acute than disc osteophyte complexes or broad disc bulges, although acute pathology can be superimposed on preexisting degenerative changes. Size of the disc herniation is also significant secondary to mass effect on nerves and resultant narrowing of neuroforamina or resultant spinal stenosis which should be documented regardless of morphology. Absence of findings such as degenerative disc signal or osteophytes can occasionally aid in assessing acuity. Annular tears/fissures of the intervertebral disc can be associated with trauma or degenerative change; additional descriptions such as size, whether the tear is peripheral, vertically orientated, bright on STIR imaging, or demonstrates a radial component (extends to the center) may assist in determining etiology and prognosis3-4.
Regarding extremities, edema and surrounding fluid at the site of pathology on MRI are helpful findings that may suggest acuity. Unusual injuries in a symptomatic young patient following trauma such as a rotator cuff tear or large SLAP tear (superior labral tear) in the shoulder or a complex meniscal tear in the knee do not typically present a diagnostic dilemma as to traumatic causality. Alternatively, joint space narrowing, subchondral cystic changes and uniform cartilage loss are not acute posttraumatic findings.
Traumatic Brain Injury
Traumatic brain injury often occurs at the grey-white matter junction due to differing densities of the grey (cortical) and white (subcortical) matter. These shearing injuries (diffuse axonal injuries) may be hemorrhagic or non-hemorrhagic. The hemorrhagic injures are best seen on SWI (susceptibility weighted imaging), which is 4-6 times more sensitive than dedicated hemo-sensitive gradient echo images5. Sagittal FLAIR imaging provides added sensitivity for the non-hemorrhagic lesions. Cerebral contusions, subdural hematomas and characteristic ‘coup contrecoup’ patterns are assessed utilizing standard brain sequences.
Diffuse Tensor Imaging (DTI) measures water diffusion along the white matter axons (which can be thought of as “telephone lines” of the brain). Decreased DTI values following head trauma is well documented in the literature and correlates with clinical outcome6. NeuroQuant hippocampal volumetric software analysis adds objective quantification in assessing the
hippocampal volume loss associated with head trauma7.
In addition, advanced trauma brain protocol may include functional (fMRI)8, perfusion imaging9 performed with contrast or using arterial spin labeling (ASL), and MR spectroscopy10.
Of course, any imaging findings, regardless of modality, should be assessed in the proper clinical context and absence of supporting imaging findings does not exclude injury. Clinical corroboration is always advised.
Dr. Snyder is a 2009 Touro University of Nevada Osteopathic Medical School graduate and a current assistant adjunct professor of Radiology and Neuroradiology at Touro. He completed his Radiology residency at McLaren Macomb (Michigan State) in Michigan and his Neuroradiology fellowship at the University of Miami and returned to Las Vegas to practice at SimonMed Imaging in Las Vegas. He has special interest in teaching rotating medical students, lecturing, and research on advanced imaging techniques for traumatic brain injury and carbon monoxide poisoning.
- 3-T MRI of the Shoulder: Is Arthrography Necessary? Magee, T. AJR Jan 2009 Volume 192, Issue 1
- Guides to the Evaluation of Permanent Impairment, Sixth Edition 6. American Medical Association.
- Annular Tears and Disc Degeneration in the Lumbar Spine. A post-mortem study of 135 discs Osti OL, Vernon-Roberts B et al. J Bone Joint Surg Br. 1992 Sep;74(5):678-82.
- Do Presence and Location of Annular Tear Influence Clinical outcome after Lumbar total Disc Arthroplasty? A prospective 1-year follow-up study James J. Yue, et al Int J Spine Surg. 2012; 6: 13–17.
- Hemorrhagic Shearing Lesions in Children and Adolescents with Posttraumatic Diffuse Axonal Injury: Improved Detection and Initial Results. Tong et al. Radiology 2003; 227:332–339.
- A Decade of DTI in Traumatic Brain Injury: 10 Years and 100 Articles Later M.B. Hulkower, et al. American Journal of Neuroradiology November 2013, 34 (11) 2064-2074.
- Man Versus Machine Part 2: Comparison of Radiologists’ Interpretations and NeuroQuant Measures of Brain Asymmetry and Progressive Atrophy in Patients With Traumatic Brain Injury. Ros DE, et al J Neuropsychiatry Clin Neurosci. 2015;27(2):147-52. doi: 10.1176/appi. neuropsych.13040088.
- Functional MRI of Mild Traumatic brain injury (mTBI): Progress and Perspectives from the first Decade of Studies. McDonald B et al. Brain Imaging Behav. 2012 Jun; 6(2): 193–207.
- Perfusion Deficits in Patients with mild Traumatic Brain injury Characterized by Dynamic Susceptibility Contrast MRI. Liu W et al. NMR Biomed. 2013 Jun;26(6):651-63. doi: 10.1002/nbm.2910. Epub 2013 Mar 4.
- Proton MR Spectroscopy in Mild Traumatic Brain Injury. Bozena Kubas et al Pol J Radiol. 2010 Oct-Dec; 75(4): 7–10.
Firm, P.C. is a boutique Las Vegas law firm founded by Preston Rezaee, Esq. Preston Rezaee is also the founder and Editor in Chief of Vegas Legal Magazine.