Damian McNamara

June 22, 2016

SAN DIEGO — For people with back pain, single-photon emission CT (SPECT)/CT can improve management decisions, according to a retrospective case series presented here at the Society of Nuclear Medicine and Molecular Imaging 2016 Annual Meeting.

Whether or not to perform an injection "was the important part," but the imaging guided the type of injection, identified the most appropriate spinal level, and helped plan the needle trajectory, said investigator Oliver Edwards, MD, from the University of Utah in Salt Lake City.

"This reinforces the notion that clinical presentation combined with radiologic findings allows for a more systematic approach than a local injection approach" to the treatment of axial spine pain, Dr Edwards said.

SPECT/CT combines the sensitivity of a conventional bone scan with improved spatial resolution and better anatomic localization, he explained. The radioisotope technetium-99m-methylene diphosphonate (99mTc-MDP) binds to areas of increased blood flow and degenerative changes, which means that SPECT/CT has greater precision.

Several smaller studies — one of 33 patients (Korean J Pain. 2011;24:81-86) and another of 58 patients (Br J Rheumatol. 1996;35:1269-1273) — have supported the use of SPECT/CT for facet joint pain injections.

"Our hope was that with a larger study, we would see similar results," Dr Edwards said.

Chronic Back Pain With Possible Facet Involvement

His team evaluated 113 patients with chronic back pain for at least 6 weeks, possible facet joint pain (determined on physical exam), and facet arthropathy seen on imaging. The patients weren't sufficiently helped by physical therapy or pain medications.

In the study cohort, 56% of pain was lumbar or sacral, 41% was cervical, and 4% was located in the thoracic spine. In addition, 77% of the patients had elevated 99mTc-MDP uptake in at least one facet joint, and 69% received either a targeted facet joint injection or a medial branch block. Mean of the cohort was 60 years.

Average visual analog scale scores improved from 4.9 before targeted facet joint injection to 1.5 after. In addition, 49% of the patients proceeded to radiofrequency ablation, and 76% of these patients experienced pain relief for at least 1 month.

Overall, SPECT/CT guidance was associated with clinical improvement in 62% of patients, Dr Edwards reported.

The fact that the study included no age-matched control group is a possible limitation, he acknowledged. And the study design precluded the calculation of false-positive rates, false-negative rates, and predictive values.

Questions About Cost

This is a "very interesting study that raises important questions that should be followed up," said Edward Silberstein, MD, from the University of Cincinnati Medical Center. However, he raised a few concerns about cost, appropriate use of resources, and some aspects of the study design.

"Even though we have all these wonderful modalities for looking at the back — CT, SPECT, and others — it may be an unnecessary use of a lot of money," Dr Silberstein told Medscape Medical News. A number of societies, driven in part by concerns about expense, are developing appropriate-use criteria for medical imaging, he added.

In this study, "we didn't know how long the patients had back pain," Dr Silberstein pointed out. And "SPECT is expensive, so it would have been nice to have a control group," he explained.

Dr Edwards and Dr Silberstein have disclosed no relevant financial relationships.

Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2016 Annual Meeting: Abstract 321. Presented June 14, 2016.

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