The Diagnostic Performance of Skeletal 99mTc-MDP SPECT/CT in Patients With Low Back Pain

Low back pain(LBP) is extremely common. Though estimates vary widely, studies in developed countries report one year prevalence of 22-65% and lifetime prevalence up to 84%. (Walker, 2000) (1) The differential diagnosis for back pain is broad and includes degenerative disease, infection, inflammation, tumors and trauma(Zukotynski, Curtis et al. 2010) (2). The etiology of low back pain in young athletes differs from that seen in adults, with bony etiology being more common than disc-related disease(Matesan, Behnia et al. 2016) (3).

The American College of Physicians and the American Pain Society classify LBP into the following broad categories: nonspecific LBP, back pain potentially associated with radiculopathy or spinal stenosis, and back pain potentially associated with another specific spinal cause. Additionally, guidelines emphasize a focused history and physical examination, reassurance, initial pain management medications if necessary, and consideration of physical therapies without imaging in patients with nonspecific LBP. Duration of symptoms also helps guide treatment algorithms in patients with acute, sub-acute, or chronic LBP.(Chou, Qaseem et al. 2011) (4).

Many imaging modalities are available to the clinician and radiologist for evaluating LBP. Application of these modalities depends on the working diagnosis, the urgency of the clinical problem, and comorbidities of the patient. Radiographs of the lumbar spine are not routinely recommended in acute nonspecific LBP because they are of limited diagnostic value. Radiography is the initial imaging study of choice for assessing LBP in patients with a history of trauma and patients suspected of possible vertebral compression fracture.In addition, radiographs are recommended to evaluate a young patient for ankylosing spondylitis.(Jarvik, Gold et al. 2015) (5)

Patients with LBP lasting for >6 weeks having completed conservative management with persistent radiculopathic symptoms, may seek magnetic resonance imaging (MRI). Patients with severe or progressive neurologic deficit on presentation and red flags should be evaluated with MRI. Computed tomography (CT) scans provide superior bone detail but are not as useful in depicting soft tissue pathologies such as disc disease when compared with MRI. CT is useful for revealing bone structural problems such as spondylolysis, pseudarthrosis, fracture, scoliosis, and stenosis and for postsurgical evaluation of bone graft integrity, surgical fusion, and instrumentation (Brinjikji, Luetmer et al. 2015) (6)

Tc-99m methylene diphosphonates bone scan is a highly sensitive technique for detection of bone diseases and can allow the detection of the pathophysiology of trauma at a very early stage. Due its excellent sensitivity it is often used as a screening tool, however limited anatomical details result in poor specificity, It can be performed as limited or whole body bone scintigraphy (Van der Wall, Lee et al. 2010) (7). Dynamic and blood pool phases can increase specificity in the diagnosis of inflammatory pathology, but they are not routinely used in cases of facet joint disease (Shur, Corrigan et al. 2015) (8)