Study notes SPECT-CT as influential in making talar lesion treatment decisions

Using SPECT-CT images surgeons improved their assessment of osteochondral lesion size by 77%.

Issue: November 2009

VANCOUVER, British Columbia — Research comparing MRI and single-photon emission computed tomography scans of osteochondral lesions of the talus reveals that single-photon emission computed tomography images caused physicians to change 59% of their treatment decisions.

“Talus osteochondral lesions can be better treated if you have a better diagnostic tool,” Victor Valderrabano, MD, PhD, said during his presentation at the 25th Annual Summer Meeting of the American Orthopaedic Foot and Ankle Society. “Single-photon emission computed tomography (SPECT-CT) gives you the biologic information with CT accuracy. It influences the treatment choice and gives you a better diagnostic for the size of the lesion and also the subchondral plate.”

During a discussion of the paper an audience member asked Valderrabano about the additional information SPECT-CT provides. Valderrabano noted that the imaging gives surgeons information regarding osteoblastic activity and bony morphology.

“It gives you information that the MRI does not, and the MRI can lead you in a bad decision-making approach,” Valderrabano said, noting that MRI scans can cause surgeons to over-estimate lesion size.

Victor Valderrabano, MD, PhD, said osteochondral lesions could be better treated if surgeons had better diagnostic tools.

Image: Brockenbrough G, Orthopedics Today

MRI vs. SPECT-CT

To determine the influence of SPECT-CT images on surgeons’ decision-making, Valderrabano and colleagues asked three orthopedic foot and ankle surgeons to analyze the MRI and SPECT-CT scans of 26 patients with osteochondral lesions of the talus. Although the surgeons were blinded to the imaging modality used for the scans, they had experience treating osteochondral lesions of the talus and using MRI and SPECT-CT for decision-making.

For each image, the surgeons were asked to interpret the subchondral bone plate morphology and the size of the lesion. They were also asked to determine the presence of kissing lesions, subchondral cysts and subchondral sclerosis. Based on each scan, the surgeons chose one of the following treatments:

microfracture;
excision and debridement;
osteochondral autologous transplantation;
retrograde drilling; or
other treatments.

Integrity of the plate

The investigators discovered that analyzing images taken with SPECT-CT caused the surgeons to change 46 of 78 treatment decisions. The investigators found that surgeons commonly choose retrograde drilling and microfracture, according to the study abstract. However, they discovered no correlation between MRI and SPECT-CT scans and the overall distribution of the chosen treatments.

The investigators also found that using SPECT-CT lead to a 77% improvement in determining the lesion size.

“The integrity of the subchondral bone plate, which is important in the treatment of osteochondral lesions, could be better judged by the SPECT-CT up to 69%,” Valderrabano said.

Large osteochondral lesion
SPECT-CT shows a large osteochondral lesion at the medial talar edge. The distinct uptake at the site of the lesion indicates highly increased bone remodeling of the involved bone tissue.

Image: Valderrabano V; Wiewiorski M

For more information:

Victor Valderrabano, MD, PhD, can be reached at the Orthopaedic Department, University Hospital of Basel, Spitalstrasse 21, Basel CH-4031, Switzerland; 41-61-265-7197; e-mail: vvalderrabano@uhbs.ch. He receives research or institutional support from Synthes and Orthocon.

Reference:

Valderrabano V, Leumann A, Pagenstert G, et al. SPECT-CT: A new diagnostic tool for osteochondral lesions (OCL) of the talus- Comparison to MRI. Presented at the 25th Annual Summer Meeting of the American Orthopaedic Foot and Ankle Society. July 15-18, 2009. Vancouver, British Columbia.