Vol.:(0123456789) 1 3 Annals of Nuclear Medicine https://doi.org/10.1007/s12149-018-01324-7 ORIGINAL ARTICLE Distribution of bone tracer uptake in symptomatic knees after ACL reconstruction compared to asymptomatic non-operated knees: a method for better diferentiating patient-specifc from disease- specifc bone tracer uptake in SPECT/CT Dominic T. Mathis 1  · Lukas Büel 1  · Helmut Rasch 2  · Felix Amsler 3  · Michael T. Hirschmann 1,4  · Rolf W. Hügli 2 Received: 10 November 2018 / Accepted: 16 December 2018 © The Japanese Society of Nuclear Medicine 2019 Abstract Objective To evaluate the diferences of bone tracer uptake (BTU) in symptomatic and asymptomatic contralateral knees in patients after reconstruction of the anterior cruciate ligament (ACL-R) and to identify typical BTU patterns and threshold values to diferentiate pathological from physiological BTU. Methods 53 patients after unilateral ACL-R were retrospectively included in the study. The population was subdivided into a group of symptomatic operated knees and a group of contralateral asymptomatic non-operated knees. BTU was measured in SPECT/CT using a validated anatomical localization-scheme and normalized mean BTU values were calculated in both knees. Wilcoxon signed rank-test and Pearson’s rank-correlation coefcient were used (p < 0.05). Results Symptomatic knees after ACL-R showed signifcantly more BTU than asymptomatic ones (p < 0.01).Based on the measured BTU activity in SPECT/CT in symptomatic operated and asymptomatic non-operated knees, intensity thresholds of pathological BTU were established. A BTU threshold of greater than the Median + 1 SD of the asymptomatic non-operated knee was defned as pathological. In both groups the highest mean BTU was found on the femoral, tibial and patellar articular surfaces, the lowest BTU in femoral and tibial regions far from the joint. Conclusions The established BTU thresholds for SPECT/CT in knees after ACL-R help to diferentiate disease-specifc from patient-specifc BTU. It could be speculated that BTU in asymptomatic knees equates to the preoperative condition of the knee joint before ACL-R. Therefore, the results of this study help to understand in-vivo loading of the knee and ultimately lead to prediction of development of osteoarthritis in an early stage. Keywords Anterior cruciate ligament reconstructionm · SPECT CT · Physiological pattern recognition · Knee · Osteoarthritis Introduction The clinical value of combined single photon emission com- puterized tomography and computerized tomography (SPECT/ CT) is well established in patients with knee problems [1, 2]. Improved diagnostics have been reported in patients after total knee arthroplasty, patients with chondral or osteochondral lesions, patients before and after high tibial osteotomy and after ACL reconstruction [1–7]. With its most commonly used tracer 99 m-Technetium-Hydroxymethylen-Diphosphonate (HDP), which targets active osteoblasts, it allows a window into the bone remodeling as well as in-vivo loading of the joint [8, 9]. SPECT/CT allows combined assessment of structural, mechanical and functional information [6, 10]. * Dominic T. Mathis dominic.mathis@unibas.ch 1 Department of Orthopaedic Surgery and Traumatology, Kantonsspital Baselland (Bruderholz, Liestal, Laufen), 4101 Bruderholz, Switzerland 2 Institute of Radiology and Nuclear Medicine, Kantonsspital Baselland, 4101 Bruderholz, Switzerland 3 Amsler Consulting, Gundeldingerrain 111, 4059 Basel, Switzerland 4 University of Basel, 4000 Basel, Switzerland