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CASE REPORT
Year : 2006  |  Volume : 21  |  Issue : 1  |  Page : 25-26 Table of Contents   

Tc99m MDP Bone Scan in Low Backache - is SPECT Necessary?


Department of Nuclear Medicine, PGIMER, Chandigarh, India

Correspondence Address:
Anish Bhattacharya
Department of Nuclear Medicine, PGIMER, Chandigarh 160012
India
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Source of Support: None, Conflict of Interest: None


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   Abstract 

Bone scintigraphy is routinely performed to identify bone and joint abnormalities in patients with low back pain.Urinary contamination by radiotracer excreted through the renal route may complicate scan interpretation, especially when localized to the symptomatic anatomical region. We present such a case where urinary contamination simulating a bony abnormality on the planar image was clearly identified only on SPECT.

Keywords: Bone scan, SPECT, urinary artifact


How to cite this article:
Bhattacharya A, Mittal BR, Prasad V, Singh B. Tc99m MDP Bone Scan in Low Backache - is SPECT Necessary?. Indian J Nucl Med 2006;21:25-6

How to cite this URL:
Bhattacharya A, Mittal BR, Prasad V, Singh B. Tc99m MDP Bone Scan in Low Backache - is SPECT Necessary?. Indian J Nucl Med [serial online] 2006 [cited 2019 Aug 23];21:25-6. Available from: http://www.ijnm.in/text.asp?2006/21/1/25/43437


   Introduction Top


Tc99m Methylene Diphosphonate (MDP) bone scintigraphy is a routine investigation in the diagnosis of low back pain, especially when radiography is normal. While the sensitivity of this imaging procedure is high, various technical and procedural artifacts should be kept in mind when interpreting positive scan findings.


   Case Report Top


A 17-year-old female patient was referred to our department for investigation of low back pain occurring intermittently for several months. Pain was localized to the left sacro-iliac joint, with radiation to the left lower limb, and was relieved by oral analgesics. There was no history of trauma in the recent past, or any bony pain elsewhere in the body. A plain radiograph of the pelvis was normal.

Three-phase bone scintigraphy was performed. Following intravenous injection of 20 mCi of Tc99m Methylene Diphosphonate, sequential dynamic images were acquired immediately in the posterior projection under a gamma camera (Ecam, Siemens; Germany). Subsequently, static images were acquired after 3-4 minutes, and again after 3 hours. The vascular phase and blood pool images showed normal flow and soft tissue uptake of tracer in the lumbosacral region; the delayed image at 3 hours showed two small foci of radiotracer concentration on the right lateral border of the L5 vertebra and right side of the sacrum [Figure 1].

Single photon emission computed tomographic (SPECT) imaging of the lumbosacral spine was therefore performed in order to identify the bony structure involved. However, both foci of tracer concentration were found to be located superficially on the body surface, and did not correspond to any bony structure [Figure 2]. A second image acquired after a complete change of clothing showed normal physiological distribution of tracer in the spine and pelvis [Figure 3], with disappearance of the two foci seen earlier. It was concluded that urinary contamination of the clothing was responsible for the abnormal foci of tracer seen on the first scan.


   Discussion Top


Sacroiliitis is a common cause of low backache in women and it can be objectively diagnosed by sacroiliac bone scintigraphy even when radiographs are normal [1] . While both planar and SPECT bone scintigraphy have been used in the diagnosis of this condition, the latter is reported to have a higher sensitivity as well as specificity [2],[3] . SPECT bone scanning of the lumbar spine is also useful in management of patients with low backache and suspected spondylosis [4] .

Tc99m Methylene Diphosphonate (MDP) is the most commonly used radiopharmaceutical in bone scintigraphy at present. Since it is excreted through the kidneys [5] , the possibility of urinary contamination of the clothes and body surface should always be kept in mind when interpreting "hot spots" on bone scans, especially in the region of the pelvis and thighs [6],[7] . In a patient with clinical symptoms localized to the lower back, as in the present case, such an artifact on anteroposterior planar imaging should be kept in mind, as the superficial location of the abnormal spot may be detected only on lateral or oblique views, or on SPECT imaging.


   Acknowledgement Top


The authors gratefully acknowledge Mr Madan Parmar for technical assistance in processing the scintigraphic images.

 
   References Top

1.Davis P, Lentle BC. Evidence for sacroiliac disease as a common cause of low backache in women. Lancet 2: 496-7, 1978.  Back to cited text no. 1    
2.Han LJ, Au-Yong TK, Tong WC, et al. Comparison of bone single­photon emission tomography and planar imaging in the detection of vertebral metastases in patients with back pain. Eur J Nucl Med 25: 635-8, 1998.  Back to cited text no. 2    
3.Battafarano DF, West SG, Rak KM, Fortenbery EJ, Chantelois AE. Comparison of bone scan, computed tomography, and magnetic resonance imaging in the diagnosis of active sacroiliitis. Semin Arthritis Rheum 23:161-76, 1993.  Back to cited text no. 3    
4.Dutton JA, Hughes SP, Peters AM. SPECT in the management of patients with back pain and spondylolysis. Clin Nucl Med 25: 93-6, 2000.  Back to cited text no. 4    
5.Britton KE: Diagnostic applications. In: Sampson CB (Ed): Textbook of radiopharmacy theory and practice (3rd ed). Gordon and Breach Science publishers, Amsterdam, Netherlands, 1999, pp. 337-367.  Back to cited text no. 5    
6.Daral TS, Bhatnagar P, Rawat H, et al. An unusual urinary artifact. Ind J Nucl Med 16: 91-92, 2001.  Back to cited text no. 6    
7.Chen SM, Yen TC, Yeh SH. Urinary extravasation detected by technetium-99m bone scan. Clin Nucl Med 19:249-50, 1994.  Back to cited text no. 7    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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    Introduction
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