Thesis

73 SPECT/CT in the post-operative painful knee iterative wavelet reconstruction techniques [42]. Several vendors of SPECT/CT-scanners now offer metal artefact suppression in order to further increase image quality. As malalignment is a major contributor to a failing knee prosthesis, correct information on the stance of the operated leg is of importance. The Imperial knee protocol, as described by Henckel, et al. in 2006, is useful to assess the necessary measurements and to evaluate mal-alignment [43]. The CT-part for these very lowdose registrations of the hip, knee, ankle and scout view (scanogram) add an effective dose of 64 to 84 mrem (0.64 to 0.84 mSv) [43]. The use of 3D volume-rendered CT images gives the most precise alignment information and is recommended if available [43, 44]. Evidence-based indications for SPECT/CT Scintigraphy is a proven complementary modality to X-ray and MRI in many postoperative knee patients [7, 41, 44, 45]. SPECT/CT offers vastly improved localization, increased accuracy and only a very marginal extra radiation dose when scanning the post-operative knee, adding 16mrem (0.16 mSv) for full-dose CT of the knee, in comparison to planar scintigraphy [41, 44-47]. A downside of SPECT/CT when compared to planar scintigraphy is an increase of direct costs. There are no studies known to us that weigh the added costs of SPECT/CT against the extra gain in diagnostic accuracy and consequent improved care in patients with a post-operative painful knee. Performing a separate CT in addition to the scintigraphy as opposed to SPECT/CT, leads to extra appointments for the patient, no integrated conclusion and less accurate correlation between functional and anatomic findings. Table 2 summarizes an overview of best evidence literature regarding SPECT/CT in postoperative pain after TKA. A very low threshold should therefore be used to replace planar images by SPECT/CT of a post-operative knee, if available and if local costs are acceptable (reimbursement may vary from country to country). Subsequently, 3D volume-rendering CT images offer a superior analysis of the mechanical leg alignment and the degree of correction and should be used in post-operative knee if possible [1, 7]. In this way bone-SPECT/CT offers joint biological and biomechanical information leading to clinically relevant findings that influence patient management and improves outcome [44]. 3

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