4D-SPECT/CT in orthopaedics: a new method of combined quantitative volumetric 3D analysis of SPECT/CT tracer uptake and component position measurements in patients after total knee arthroplasty
Summary (2 min read)
Introduction
- Single-photon emission computed tomography /CT is becoming an increasingly available diagnostic imaging modality worldwide [1–8].
- The clinical diagnostic benefits of SPECT/CT for orthopaedic patients such as the combination of functional, structural and mechanical information have been particularly highlighted for patients with problems after total knee arthroplasty (TKA) [4, 8–11] (Figs. 1, 2 and 3).
- Others used more descriptive methods to characterise areas of altered SPECT tracer uptake [1, 9, 11–13].
- Such a three-dimensional approach to SPECT data analysis promises a richer source of clinical information and allows quantitative comparison of SPECT/CT measurements across patients [14].
- Together with the determination of TKA component position in 3D-CT, it represents a novel approach to biomechanics in patients after TKA [15].
Materials and methods
- Included was a consecutive series of patients undergoing SPECT/CT because of persistent pain after TKA.
- For tracer uptake analysis (intensity and anatomical distribution pattern) the 3D-reconstructed datasets of the delayed SPECT/CT images were used.
- The position of the femoral and tibial TKA component was assessed on 3D-CT after reorientation to the mechanical axis.
- Sample size was estimated according to the reported estimates for reliability studies using intraclass correlation coefficients (ICCs) [17].
Results
- The absolute measurements of tracer intensity for each anatomical area and the ratios (in relation to the background intensity of the distal femur) of both observers are presented in Tables 1 and 2.
- The measurements of tracer uptake intensity using this 3D voxel-based analysis showed very good interand intra-observer reliabilities for all regions (tibia, femur and patella).
- Only the tibial shaft area showed ICCs <0.89.
- Table 4 compares the areas indicating the maximum tracer uptake when measured by each observer.
- For measurement of the femoral and tibial component position, there was strong agreement between the readings of the two observers; the ICCs for the orientation of the femoral and tibial components for inter- and intra-observer reliability were >0.84, which is nearly perfect.
Discussion
- The proposed method of combined quantitative 3D analysis of SPECT tracer uptake and measurements of TKA component position reflects a novel approach to biomechanics in patients after TKA.
- The most important findings and implications of their present study are threefold:.
- The maximum uptake value in each anatomical area was almost perfectly reliable.
- Third, the determination of femoral and tibial TKA component position in 3D-CT was highly reliable.
Conclusions
- The proposed combined 3D-volumetric standardised method of analysing the location, size and the intensity of SPECT/CT tracer uptake regions (“hotspots”), as well as the determination of TKA component position, is highly reliable.
- Its clinical value will be further investigated in prospective clinical studies.
- The authors greatly thank the Gottfried und Julia Bangerter-Rhyner-Stiftung, Berne, Switzerland as well as the Deutsche Arthrose Hilfe e.V, Saarlouis, Germany for supporting their research.
- The authors declare that they have no conflict of interest.
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Citations
74 citations
Cites background from "4D-SPECT/CT in orthopaedics: a new ..."
...A novel four-dimensional SPECT/CT approach correlates tracer uptake and joint replacement component positioning in patients after total knee arthroplasty, showing excellent inter- and intraobserver reliabilities, and might therefore be the evaluation standard of the future [42, 43]....
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57 citations
Cites methods from "4D-SPECT/CT in orthopaedics: a new ..."
...The coronal (varus–valgus) alignment was determined with reference to the mechanical axis, according to different anatomical landmarks which have been previously proven to be available and reliable [34]....
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51 citations
Cites background or methods from "4D-SPECT/CT in orthopaedics: a new ..."
...They reported near perfect inter- and intra-observer reliability for their proposed standardized SPECT/CT algorithm including a localization scheme, intensity value and 3-D prosthetic component analysis [3, 6]....
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...In previous studies this measurement method was shown to be highly accurate [2, 3, 23, 24]....
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...highlighted the clinical value of a standardized diagnostic algorithm including SPECT/CT in patients with problems after TKA [3]....
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...85, which is considered to be a near perfect reliability [3]....
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...3 Measurement of femoral and tibial TKA component positions (varus-valgus, flexion-extension, internal rotation-external rotation) in 3-D reconstructed CT images using a customized software [3]...
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46 citations
Cites background or methods from "4D-SPECT/CT in orthopaedics: a new ..."
...The sagittal (flexion–extension), coronal (varus–valgus) and rotational alignment (internal rotation–external rotation) were determined with reference to the mechanical axis, according to different anatomic landmarks which have been previously proven to be available and reliable [24]....
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...75-mm slices of the knee and 3-mm slices of the hip and ankle joints [24]....
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41 citations
Cites background or methods from "4D-SPECT/CT in orthopaedics: a new ..."
...Konigsberg et al. found a poor interobserver ICC for the femoral component of 0.386 and a good intraobserver ICC of 0.606 [23] measured with 2D-CT....
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...Hirschmann et al. [18] reported a very good intraobserver (ICC of 0.93) and interobserver reliability (ICC 0.88)....
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...The overall measurements for intraobserver and interobserver reliability were good (ICC 0.809 and ICC 0.67) according to Konigsberg et al. [23] for 2D-CT measurements....
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...Four studies reported levels of accuracy using intraclass correlation coefficients (ICC) [18, 19, 23, 29]....
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...Hirschmann et al. [18, 19] reported a very good intraobserver reliability (ICC of 0.97 and 0.99) and interobserver reliability (ICC 0.95 and 0.99) in two studies....
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References
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Frequently Asked Questions (2)
Q2. What are the future works in "4d-spect/ct in orthopaedics: a new method of combined quantitative volumetric 3d analysis of spect/ct tracer uptake and component position measurements in patients after total knee arthroplasty" ?
Its clinical value will be further investigated in prospective clinical studies.