SPECT/CT bone scintigraphy to evaluate low back pain in young athletes: common and uncommon etiologies
© The Author(s). 2016
Received: 15 February 2016
Accepted: 26 May 2016
Published: 7 July 2016
Low back pain of various etiologies is a common clinical presentation in young athletes. In this article, we discuss the utility of SPECT/CT bone scintigraphy for the evaluation of low back pain in young athletes. The spectrum of lower spine lesions caused by sports injuries and identifiable on bone scan is presented along with strategies to avoid unnecessary irradiation of young patients. Also covered are pitfalls in diagnosis due to referred-pain phenomenon and normal skeletal variants specific to this age group.
KeywordsSPECT/CT Back pain Young athletes Referred pain
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 [1,2]. Chronic low back pain occurs more often than acute pain and is caused by repetitive microtrauma due to flexion, extension, and rotation movements that increase the risk of injury to the posterior elements of the spine.
The initial evaluation of a young adult with back pain starts with lumbar spine radiograph; however this has limited sensitivity in the detection of pars fractures and stress reactions. MRI is preferred if neurologic symptoms are present or if radicular pain is identified on clinical exam. In the absence of neurologic symptoms, evaluation can proceed by bone scintigraphy with planar and SPECT acquisitions. Bone scintigraphy can differentiate acute spondylolysis from old chronic nonunion fracture, and there is a good correlation between a positive bone scan and painful pars lesion . Bone scan with SPECT is superior to MRI and CT in the detection of spondylolysis . One study comparing SPECT and CT versus MRI showed that only 40 out of 50 lesions seen on SPECT were revealed by MRI and there was no case of positive MRI with negative SPECT .
Besides evaluation for marrow edema at the pars interarticularis (high signal intensity on STIR images and low signal in T1), MRI offers a good evaluation of surrounding soft tissue lesion (like posterior ligamentous complex), spinal cord, and intervertebral disc.
18F NaF PET scan has been also shown to be useful in the detection of a variety of skeletal abnormalities in young patients with back pain with higher resolution and similar radiation dosimetry but a higher cost relative to Tc99m-MDP .
SPECT images have better contrast resolution compared to planar images and detect additional sites of abnormal uptake, in one study performed in patients with low back pain in 24 % of the cases . The large field-of-view surveyed by planar whole-body imaging offers the advantage of identifying additional abnormal bony sites that may trigger referred pain or mimic radicular pain unsuspected upon initial clinical evaluation.
Referred pain in the lower lumbar region originating from the sacroiliac joint and hip can be explained by the common innervation of the hip/sacroiliac joints and intervertebral discs by sacral and lower lumbar nerves [7,8]. Studies have shown that patients with low back pain, with or without leg pain, may have the spine, sacrum/sacroiliac joints, or hip as the cause of their symptoms [7–9]. A study published by Sembrano et al. in patients with low back pain, with or without leg pain, showed that in 65 % of cases, the major pain generator came from the spine only; in 5 %, it originated from the sacroiliac joint only; and in 2.5 % of the cases, the back pain originated from the hip only . Because attention is directed to the referral site of pain, the area that represents the source of pain may be overlooked if the imaging field of view is limited. Therefore, correlation with clinical history and physical exam and consideration of the risk factors for a certain pathology type are important in avoiding a delay in diagnosis. For example, long distance female runners are at slightly higher risk for sacral stress fractures that clinically may manifest as low back pain and buttock pain mimicking radicular pain . Although spinal radicular pain has certain characteristics (dermatomal distribution, extension beyond the knee, and sensory or motor loss), there is a high incidence of nonradicular pain mimicking radicular pain .
Bone scan protocol
Planar (whole body or spot) scintigraphic images are obtained 3–4 h after intravenous injection of 9.3 MBq/kg (0.25 mCi/kg) of Tc99m-MDP (methylene diphosphonate), followed by SPECT acquisition with or without additional CT acquisition . Blood flow and blood pool images may be added if an acute injury is suspected. Planar images include a large area encompassing more than the site of pain to cover areas of potential referred pain.
A standard SPECT acquisition protocol for bone imaging with a dual-head gamma camera consists of 25 s per view, 60 view angles over 180° (3° increments between views), and 128 × 128 binning.
Recent SPECT-CT systems are equipped with fully diagnostic quality CT systems; however, usually, only low-dose CT is obtained for attenuation correction and for visualization of bony details over a limited field of view thereby minimizing the impact of radiation on the patient’s gonads. Our routine low-dose CT consists of a 60-mA tube current and a 0.8-s tube rotation at 120 kVp. In the absence of any abnormality on SPECT images, the CT is not performed, thereby sparing young patients the additional radiation. Rarely, a diagnostic beam CT over a limited filed of view is required for anatomic characterization.
Lumbar spine origin of low back pain
Isthmic spondylolysis represents a pars interarticularis fracture usually associated with repetitive forced hyperextension and rotation. It has a higher incidence during the adolescent growth spurt due to incomplete bone maturation of the neural arch and repetitive stress injury [1,2] but heredity also plays a role . It is common for spondylolysis to be bilateral, and the vast majority of cases occur at L5 with the next more common location being L4 . Spondylolysis usually presents with focal chronic low back pain which is unilateral or bilateral and increases with activity, without radicular symptoms.
Lumbar spine pathology other than spondylolysis
Although isthmic spondylolysis is the most common cause of low back pain in young athletes, other etiologies need to be considered. These include stress reaction or fracture at the pedicle, transitional vertebra, lumbar interspinous bursitis, traction apophysitis (at the iliac crest, spinous process, or anterior vertebral ring apophysis), facet joint disease, facet posterior fracture in the lumbar spine region, avulsion fracture of the secondary ossification centers, endplate degenerative changes, and sacral facet fracture. Ligament injuries cannot be diagnosed on bone scan unless resulting in calcification.
Pedicle stress reaction or fracture
Fractures at the vertebral apophyses
In the adolescent age range, fractures at the secondary centers of ossification of the vertebrae (apophyses) can occur since most of them are not yet fused. There are seven secondary centers of ossification (apophyses) in a lumbar vertebra as described below. On bone scan, only faint uptake is usually seen associated with these apophyses and high and asymmetric uptake at one of the secondary ossification centers is suggestive of an avulsion fracture.
Injury to the ring apophysis caused by disc material protruding through the growth plate of ring apophysis can result in limbus vertebra. This is seen as a small corticated bony fragment matching osseous defect at the superior margin usually in anterosuperior location and on imaging that needs to be differentiated from an acute vertebral fracture, a Schmorl nodule, or calcified disc herniation. Limbus vertebra is usually asymptomatic unless it has a posterior location when it can potentially cause a neurologic symptom .
Fractures of the transverse processes of the lumbar vertebrae
Fractures of the transverse processes of the lumbar vertebrae may result from violent lateral flexion-extension forces (as in football) . Fractures of the L5 transverse process raise the suspicion for sacral fracture.
Lumbosacral transitional vertebrae syndrome (Bertolotti syndrome)
Impingement syndrome of the adjacent spinous processes (Baastrup disease-lumbar interspinous bursitis)
Impingement syndrome of the adjacent spinous processes (Baastrup disease-lumbar interspinous bursitis) can be due to a tight thoracolumbar fascia with accentuated lordosis and worsened by excessive hyperextension and hyperflexion .
Facet joint can be also a source of pain if degenerative changes are present and shows increased uptake on bone scan.
Adolescent disc dysplasia
Referred lower lumbar pain
Referred lower lumbar pain can be triggered by pathologic processes localized in the sacrum (sacral fractures), sacroiliac joints (sacroiliac joint syndrome), or hips [8,9]. The large field of view of planar bone scan helps in identifying these possible etiologies of lower lumbar pain.
Sacral stress fracture
Sacroiliac joint syndrome
Sacroiliac joint syndrome is due to increased sports activities with increased abnormal motion or stress at the sacroiliac joint. This can be difficult to diagnose on bone scintigraphy given the normally increased uptake in this age group patient population . Degenerative changes can be seen on CT: sacroiliac joint irregularity, subchondral cysts, and sclerosis .
Low back pain in young athletes not related to sports activity
Discitis or osteomyelitis can also present with increased uptake on bone scan. In case of discitis, there is radiotracer uptake along the affected facing endplates.
In the first few hours after acute trauma, bone scintigraphy may be falsely negative; however, sensitivity is closed to 100 % at 72 h after fracture onset .
Also, it is important to be familiar with normal skeletal development across different age groups. There are 3 primary ossification centers for a spinal vertebra and a total of 21 for sacrum, and these fuse before puberty (usually by 6–7 years old) and are normally not seen any more in the adolescent age range. However, recognizing confounding variants due to failure of the segmentation process or fusion abnormalities of these centers is important [15,31].
Bone scan is a useful clinical tool to explore the etiology of low back pain like spondylolysis and other less common etiologies in young athletes. It is also particularly important to detect the active source of pain when more than one bony abnormality is seen in anatomical imaging. The addition of SPECT-CT increases the clinical accuracy due to increased contrast resolution and anatomical localization.
MM was responsible for the conception and design of the study. MM, FB, MB, and HV collected and assembled the figures. MM, FB and MB wrote the manuscript. MM, FB, MB, and HV gave the final approval and edited the manuscript.
The authors declare that they have no competing interests.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Micheli LJ, Wood R. Back pain in young athletes. Significant differences from adults in causes and patterns. Archives of pediatrics & adolescent medicine. 1995;149(1):15–8. Epub 1995/01/01.View ArticleGoogle Scholar
- Standaert CJ. Low back pain in the adolescent athlete. Physical medicine and rehabilitation clinics of North America. 2008;19(2):287–304. doi:https://doi.org/10.1016/j.pmr.2008.01.002. ix. Epub 2008/04/09.View ArticlePubMedGoogle Scholar
- Lowe J, Schachner E, Hirschberg E, Shapiro Y, Libson E. Significance of bone scintigraphy in symptomatic spondylolysis. Spine. 1984;9(6):653–5. Epub 1984/09/01.View ArticlePubMedGoogle Scholar
- Masci L, Pike J, Malara F, Phillips B, Bennell K, Brukner P. Use of the one‐legged hyperextension test and magnetic resonance imaging in the diagnosis of active spondylolysis. British Journal of Sports Medicine. 2006;40(11):940–6. doi:https://doi.org/10.1136/bjsm.2006.030023.View ArticlePubMedPubMed CentralGoogle Scholar
- Lim R, Fahey FH, Drubach LA, Connolly LP, Treves ST. Early experience with fluorine-18 sodium fluoride bone PET in young patients with back pain. Journal of pediatric orthopedics. 2007;27(3):277–82. doi:https://doi.org/10.1097/bpo.0b013e31803409ba.View ArticlePubMedGoogle Scholar
- Bellah RD, Summerville DA, Treves ST, Micheli LJ. Low-back pain in adolescent athletes: detection of stress injury to the pars interarticularis with SPECT. Radiology. 1991;180(2):509–12. doi:https://doi.org/10.1148/radiology.180.2.1829845. Epub 1991/08/01.View ArticlePubMedGoogle Scholar
- Slipman CW, Jackson HB, Lipetz JS, Chan KT, Lenrow D, Vresilovic EJ. Sacroiliac joint pain referral zones. Archives of physical medicine and rehabilitation. 2000;81(3):334–8. Epub 2000/03/21.View ArticlePubMedGoogle Scholar
- Sembrano JN, Polly Jr DW. How often is low back pain not coming from the back? Spine. 2009;34(1):E27–32. doi:https://doi.org/10.1097/BRS.0b013e31818b8882. Epub 2009/01/08.View ArticlePubMedGoogle Scholar
- Bernard Jr TN, Kirkaldy-Willis WH. Recognizing specific characteristics of nonspecific low back pain. Clinical orthopaedics and related research. 1987;217:266–80. Epub 1987/04/01.PubMedGoogle Scholar
- Fredericson M, Salamancha L, Beaulieu C. Sacral stress fractures: tracking down nonspecific pain in distance runners. The Physician and sportsmedicine. 2003;31(2):31–42. doi:https://doi.org/10.3810/psm.2003.02.189. Epub 2003/02/01.View ArticlePubMedGoogle Scholar
- Gelfand MJ, Parisi MT, Treves ST. Pediatric radiopharmaceutical administered doses: 2010 North American consensus guidelines. J Nucl Med. 2011;52(2):318–22. doi:https://doi.org/10.2967/jnumed.110.084327. Epub 2011/01/15.View ArticlePubMedGoogle Scholar
- Fredrickson BE, Baker D, McHolick WJ, Yuan HA, Lubicky JP. The natural history of spondylolysis and spondylolisthesis. The Journal of bone and joint surgery American volume. 1984;66(5):699–707. Epub 1984/06/01.PubMedGoogle Scholar
- Amato M, Totty WG, Gilula LA. Spondylolysis of the lumbar spine: demonstration of defects and laminal fragmentation. Radiology. 1984;153(3):627–9. doi:https://doi.org/10.1148/radiology.153.3.6494460. Epub 1984/12/01.View ArticlePubMedGoogle Scholar
- Sherman FC, Wilkinson RH, Hall JE. Reactive sclerosis of a pedicle and spondylolysis in the lumbar spine. The Journal of bone and joint surgery American volume. 1977;59(1):49–54. Epub 1977/01/01.PubMedGoogle Scholar
- Tehranzadeh J, Andrews C, Wong E. Lumbar spine imaging. Normal variants, imaging pitfalls, and artifacts. Radiologic clinics of North America. 2000;38(6):1207–53. v-vi. Epub 2000/12/29.View ArticlePubMedGoogle Scholar
- Amari R, Sakai T, Katoh S, Sairyo K, Higashino K, Tachibana K, et al. Fresh stress fractures of lumbar pedicles in an adolescent male ballet dancer: case report and literature review. Archives of orthopaedic and trauma surgery. 2009;129(3):397–401. doi:https://doi.org/10.1007/s00402-008-0685-8. Epub 2008/07/09.View ArticlePubMedGoogle Scholar
- Johansen JG, McCarty DJ, Haughton VM. Retrosomatic clefts: computed tomographic appearance. Radiology. 1983;148(2):447–8. doi:https://doi.org/10.1148/radiology.148.2.6867340. Epub 1983/08/01.View ArticlePubMedGoogle Scholar
- Yagan R. CT diagnosis of limbus vertebra. Journal of computer assisted tomography. 1984;8(1):149–51. Epub 1984/02/01.View ArticlePubMedGoogle Scholar
- Brynin R, Gardiner L. Missed lumbar transverse process fractures in a high school football player. Journal of manipulative and physiological therapeutics. 2001;24(2):123–6. doi:https://doi.org/10.1067/mmt.2001.112562. Epub 2001/02/24.View ArticlePubMedGoogle Scholar
- Connolly LP, d'Hemecourt PA, Connolly SA, Drubach LA, Micheli LJ, Treves ST. Skeletal scintigraphy of young patients with low-back pain and a lumbosacral transitional vertebra. Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2003;44(6):909–14. Epub 2003/06/07.Google Scholar
- Tague RG. High assimilation of the sacrum in a sample of American skeletons: prevalence, pelvic size, and obstetrical and evolutionary implications. American journal of physical anthropology. 2009;138(4):429–38. doi:https://doi.org/10.1002/ajpa.20958. Epub 2008/12/04.View ArticlePubMedGoogle Scholar
- Konin GP, Walz DM. Lumbosacral transitional vertebrae: classification, imaging findings, and clinical relevance. AJNR American journal of neuroradiology. 2010;31(10):1778–86. doi:https://doi.org/10.3174/ajnr.A2036. Epub 2010/03/06.View ArticlePubMedGoogle Scholar
- DePalma MJ, Slipman CW, Siegelman E, Bayruns TJ, Bhargava A, Frey ME, et al. Interspinous bursitis in an athlete. The Journal of bone and joint surgery British volume. 2004;86(7):1062–4. Epub 2004/09/28.View ArticlePubMedGoogle Scholar
- Anakwenze OA, Kancherla V, Rendon N, Drummond DS. Adolescent disc dysplasia and back pain. Journal of Children's Orthopaedics. 2011;5(1):49–53. doi:https://doi.org/10.1007/s11832-010-0302-6.View ArticlePubMedGoogle Scholar
- Johnson AW, Weiss Jr CB, Stento K, Wheeler DL. Stress fractures of the sacrum. An atypical cause of low back pain in the female athlete. The American journal of sports medicine. 2001;29(4):498–508. Epub 2001/07/31.PubMedGoogle Scholar
- Slipman CW, Sterenfeld EB, Chou LH, Herzog R, Vresilovic E. The value of radionuclide imaging in the diagnosis of sacroiliac joint syndrome. Spine. 1996;21(19):2251–4. Epub 1996/10/01.View ArticlePubMedGoogle Scholar
- Chen YC, Fredericson M, Smuck M. Sacroiliac joint pain syndrome in active patients: a look behind the pain. The Physician and sportsmedicine. 2002;30(11):30–7. doi:https://doi.org/10.3810/psm.2002.11.527. Epub 2002/11/01.View ArticlePubMedGoogle Scholar
- Etemadifar MR, Hadi A. Clinical findings and results of surgical resection in 19 cases of spinal osteoid osteoma. Asian spine journal. 2015;9(3):386–93. Epub 2015/06/23. doi: 10.4184/asj.2015.9.3.386. PubMed PMID: 26097653; PubMed Central PMCID: PMCPmc4472586.View ArticlePubMedPubMed CentralGoogle Scholar
- Lisbona R, Rosenthall L. Role of radionuclide imaging in osteoid osteoma. AJR American journal of roentgenology. 1979;132(1):77–80. doi:https://doi.org/10.2214/ajr.132.1.77. Epub 1979/01/01.View ArticlePubMedGoogle Scholar
- Scheyerer MJ, Pietsch C, Zimmermann SM, Osterhoff G, Simmen HP, Werner CM. SPECT/CT for imaging of the spine and pelvis in clinical routine: a physician's perspective of the adoption of SPECT/CT in a clinical setting with a focus on trauma surgery. European journal of nuclear medicine and molecular imaging. 2014;41 Suppl 1:S59–66. doi:https://doi.org/10.1007/s00259-013-2554-0. Epub 2013/09/24.View ArticlePubMedGoogle Scholar
- Moore KL, Persaud TVN. The developing human: clinically oriented embryology: Saunders; 2003.Google Scholar
- Broome DR, Hayman LA, Herrick RC, Braverman RM, Glass RB, Fahr LM. Postnatal maturation of the sacrum and coccyx: MR imaging, helical CT, and conventional radiography. AJR American journal of roentgenology. 1998;170(4):1061–6. doi:https://doi.org/10.2214/ajr.170.4.9530059. Epub 1998/04/08.View ArticlePubMedGoogle Scholar
- Scheuer L, Black S, Cunningham C, Christie A. Developmental juvenile osteology: Elsevier Science; 2000.Google Scholar
- Cardoso HF, Pereira V, Rios L. Chronology of fusion of the primary and secondary ossification centers in the human sacrum and age estimation in child and adolescent skeletons. American journal of physical anthropology. 2014;153(2):214–25. doi:https://doi.org/10.1002/ajpa.22422. Epub 2013/11/15.View ArticlePubMedGoogle Scholar
- Keats TE, Anderson MW. Atlas of normal roentgen variants that may simulate disease: expert consult—enhanced online features and print: Elsevier/Saunders; 2013.Google Scholar