PT  - JOURNAL ARTICLE
AU  - Jeroen Mertens
AU  - Tom Lootens
AU  - Johan Vercruysse
AU  - Bieke Van Den Bossche
AU  - Dieter Berwouts
AU  - Bieke Lambert
AU  - Tim Van den Wyngaert
TI  - Bone SPECT/CT tracer uptake analysis in the painful total ankle replacement<strong/>
DP  - 2020 May 01
TA  - Journal of Nuclear Medicine
PG  - 179--179
VI  - 61
IP  - supplement 1
4099  - http://jnm.snmjournals.org/content/61/supplement_1/179.short
4100  - http://jnm.snmjournals.org/content/61/supplement_1/179.full
SO  - J Nucl Med2020 May 01; 61
AB  - 179Objectives: To design and validate a standardized localization and scoring system for bone SPECT/CT to facilitate assessment of painful total ankle replacements (TAR). In addition, patterns of uptake associated with common complications after TAR were identified. Methods: A total of 24 TARs belonging to sixteen patients with persistent or recurrent pain and imaged with bone SPECT/CT between 2011 and 2016 were included in this study. A customized localization scheme was developed taking into account prosthesis biomechanics and failure modes. Two raters used a 5-point scale to grade and localize tracer uptake. Inter-rater agreement was estimated using intraclass correlation coefficients (ICC) to validate the localization scheme. Uptake scores were correlated with the time interval after TAR surgery and associations between scores and the final clinical diagnoses were assessed to identify diagnostic patterns. Results: An excellent inter-rater agreement was found for the standardized localization scheme with an overall ICC of 0.79 (95% CI: 0.75-0.82), with highest (ICC 0.88; 95% CI: 0.74-0.95) and lowest (ICC 0.46; 95% CI: 0.07-0.72) values for the medial gutter and the anterior mid-zone talar area (Ta2a), respectively. Tracer uptake around the TAR was negatively correlated with the time between TAR surgery and SPECT/CT imaging for all assessed areas (Pearson’s ρ=-0.470), all component interface areas (ρ =-0.475), as well as all talar areas (ρ=-0.443) (all P<0.05). The mean uptake scores in patients with medial gutter impingement were significantly higher at the medial gutter (4.65 ±0.94 vs 2.86 ±0.93; P<0.001) and the medial malleolus (3.90 ±0.94 vs 2.86 ±1.26; P< 0.05), compared to patients without medial gutter impingement. Likewise, a higher uptake was observed at the lateral gutter (4.80 ±0.27 vs 2.16 ±0.73; P<0.001) and the lateral malleolus (3.80 ±0.76 vs 1.79 ±0.96; P<0.001) in patients with lateral gutter impingement, compared to patients without lateral gutter impingement. Furthermore, increased uptake was seen at the entire tibial interface in patients with tibial loosening (3.56 ±0.57 versus 2.08 ±0.50 for all tibial areas; P<0.001). Conclusions: Reporting of bone SPECT/CT studies in patients with painful TARs may benefit from the use of the proposed standardized localization and scoring system, showing excellent inter-rater agreement and distinct patterns of uptake that are associated with common post-operative complications. In addition to the pattern of uptake, the time interval between surgery and imaging needs to be taken into account.