Bone Tracer Uptake Research Articles

Preoperative Assessment of Medication-Related Osteonecrosis of the Jaw Using [18F]fluoride Positron Emission Tomography (PET)/CT and [18F]fluorodeoxyglucose PET/MRI in Correlation with Histomorphometry and Micro-CT-A Prospective Comparative Study.

The purpose of this study was to investigate the imaging characteristics of medication-related osteonecrosis of the jaw (MRONJ) using [18F]fluoride positron emission tomography/computed tomography (PET/CT) and [18F]fluorodeoxyglucose (FDG) PET/magnetic resonance imaging (MRI) for preoperative assessment and to correlate them with microarchitectural and histomorphometric data with respect to clinical findings. Twelve patients (five female; mean age 75 ± 7.6 yr) with symptomatic MRONJ underwent both scans on the same day, and imaging findings were used to plan surgical interventions for seven patients. Bone tracer uptake was classified as high, medium, or low, and surgical samples were evaluated using Micro-CT and histomorphometric analysis. CT showed medullary sclerosis in all patients, and MRI revealed gadolinium enhancement in four patients. PET imaging revealed remarkably elevated [18F]fluoride uptake and moderately increased [18F]FDG uptake in MRONJ compared to healthy jawbones, with both differences being statistically significant. [18F]fluoride uptake was associated with necrosis, bacteria, and inflammatory tissue. Micro-CT data did not show significant differences, but histomorphometric analysis revealed higher osteocyte and lacunae densities in the high [18F]fluoride uptake group, and more necrotic bone in the medium [18F]fluoride uptake group. Bacteria were observed in all areas. In summary, [18F]fluoride PET accurately identified MRONJ extent, revealing functional changes in jawbone remodeling not visible on CT. [18F]FDG PET showed differences in bone and soft tissue, though less pronounced. This method aids in evaluating disease activity and guiding treatment planning, requiring further research for optimal surgical approaches based on tracer uptake.

Clinical and Prognostic Implications of Right Ventricular Uptake on Bone Scintigraphy in Transthyretin Amyloid Cardiomyopathy.

The extent of myocardial bone tracer uptake with technetium pyrophosphate, hydroxymethylene diphosphonate, and 3,3-diphosphono-1,2-propanodicarboxylate in transthyretin amyloid cardiomyopathy (ATTR-CM) might reflect cardiac amyloid burden and be associated with outcome. Consecutive patients with ATTR-CM who underwent diagnostic bone tracer scintigraphy with acquisition of whole-body planar and cardiac single-photon emission computed tomography (SPECT) images from the National Amyloidosis Centre and 4 Italian centers were included. Cardiac uptake was defined according to the Perugini classification: 0=absent cardiac uptake; 1=mild uptake less than bone; 2=moderate uptake equal to bone; and 3=high uptake greater than bone. Extent of right ventricular (RV) uptake was defined as focal (basal segment of the RV free wall only) or diffuse (extending beyond basal segment) on the basis of SPECT imaging. The primary outcome was all-cause mortality. Among 1422 patients with ATTR-CM, RV uptake accompanying left ventricular uptake was identified by SPECT imaging in 100% of cases at diagnosis. Median follow-up in the whole cohort was 34 months (interquartile range, 21 to 50 months), and 494 patients died. By Kaplan-Meier analysis, diffuse RV uptake on SPECT imaging (n=936) was associated with higher all-cause mortality compared with focal (n=486) RV uptake (77.9% versus 22.1%; P<0.001), whereas Perugini grade was not associated with survival (P=0.27 in grade 2 versus grade 3). On multivariable analysis, after adjustment for age at diagnosis (hazard ratio [HR], 1.03 [95% CI, 1.02-1.04]; P<0.001), presence of the p.(V142I) TTR variant (HR, 1.42 [95% CI, 1.20-1.81]; P=0.004), National Amyloidosis Centre stage (each category, P<0.001), stroke volume index (HR, 0.99 [95% CI, 0.97-0.99]; P=0.043), E/e' (HR, 1.02 [95% CI, 1.007-1.03]; P=0.004), right atrial area index (HR, 1.05 [95% CI, 1.02-1.08]; P=0.001), and left ventricular global longitudinal strain (HR, 1.06 [95% CI, 1.03-1.09]; P<0.001), diffuse RV uptake on SPECT imaging (HR, 1.60 [95% CI, 1.26-2.04]; P<0.001) remained an independent predictor of all-cause mortality. The prognostic value of diffuse RV uptake was maintained across each National Amyloidosis Centre stage and in both wild-type and hereditary ATTR-CM (P<0.001 and P=0.02, respectively). Diffuse RV uptake of bone tracer on SPECT imaging is associated with poor outcomes in patients with ATTR-CM and is an independent prognostic marker at diagnosis.

Abstract 15619: Prevalence of Transthyretin Cardiac Amyloidosis in Elderly Subjects From the General Population: The Catch Study

Introduction: The exact prevalence of transthyretin cardiac amyloidosis (ATTR-CA) in the general population has never been defined. Methods: We conducted a population screening in an area of Tuscany (Italy) where there is no cluster of variant ATTR. Six general practitioners proposed study participation to a total of 2,566 subjects aged ≥65 years, with 1,000 accepting. All subjects underwent first-line exams searching the following elements of suspicion of CA: high sensitivity-troponin T ≥14 ng/L, interventricular septal thickness ≥12 mm, any echocardiographic, ECG or clinical red flag. Individuals with any of these elements were referred to the search for a monoclonal protein and bone scintigraphy. Results: Step two exams (bone scintigraphy and search for a monoclonal protein) were proposed to 346 subjects, and 216 (62%) accepted. Three patients were ultimately diagnosed with ATTR-CA (a 79-year-old woman, an 85-year-old and a 74-year-old man), and the diagnosis was deemed likely in another patient (an 83-year-old woman with mild bone tracer uptake but intense uptake in the inferior wall, not willing to undergo endomyocardial biopsy). No patient had a monoclonal protein nor TTR gene mutations. All patients with ATTR-CA had left ventricular wall thickening and complained of dyspnea on moderate effort. The prevalence of ATTR-CA was 3 out of 870 (654 [Step two not proposed] + 216 [Step two performed]) = 0.34%, or 0.46% if considering also the fourth case. Conclusions: The prevalence of wild-type ATTR-CA in the elderly population is 0.34% (established diagnoses) or 0.46% (established or likely diagnoses).

Ureteral Stone Mimicking Metastasis - Planar Bone Scan When Single-photon Emission Computed Tomography/Computed Tomography Is a Necessity.

In this case, we demonstrated a ureteric stone that resembled bone metastasis. Because bone-seeking radiopharmaceuticals are excreted into the urine by the kidneys, normal kidneys and bladder are well visualized on skeletal scintigraphs leading to incidental detection of urinary tract abnormalities. Bone tracer uptake related to ureteral stones has been reported [Figure 1] several times before. We present a right ureteral stone mimicking abnormal focal sacral uptake on planar scan in a patient with rectal cancer. This case emphasizes the importance of using single-photon emission computed tomography/computed tomography to determine the cause of abnormal uptake on a planar scan.

Microcalcification and 99mTc-Pyrophosphate Uptake without Increased Bone Metabolism in Cardiac Tissue from Patients with Transthyretin Cardiac Amyloidosis.

Transthyretin cardiac amyloidosis (ATTR-CA) is characterized by high 99mTc-labeled bone tracer uptake in the heart. However, the mechanism of bone tracer uptake into the heart remains controversial. Since bone tracer uptake into metastatic bone tumors is thought to be associated with increased bone metabolism, we examined 99mTc-pyrophosphate (PYP) scintigraphy findings, endomyocardial biopsy (EMB) tissue findings, and the expression of bone metabolism-related genes in the EMB tissues in patients with ATTR-CA, amyloid light-chain cardiac amyloidosis (AL-CA), and noncardiac amyloidosis (non-CA) in this study. The uptake of 99mTc-PYP in the heart was significantly higher in the ATTR-CA patients than in the AL-CA and non-CA patients. A higher percentage of ATTR-CA EMB tissue showed von Kossa-positive microparticles: ATTR-CA, 62%; AL-CA, 33%; and non-CA, 0%. Calcified microparticles were identified using transmission electron microscopy. However, none of the osteogenic marker genes, osteoclastic marker genes, or phosphate/pyrophosphate-related genes were upregulated in the EMB samples from ATTR-CA patients compared to those from AL-CA and non-CA patients. These results suggest that active calcification-promoting mechanisms are not involved in the microcalcification observed in the heart in ATTR-CA. The mechanisms explaining bone tracer uptake in the heart, which is stronger than that in the ribs, require further investigation.

172 CLINICAL AND PROGNOSTIC IMPLICATIONS OF RV UPTAKE WITH RADIONUCLIDE SCINTIGRAPHY IN TRANSTHYRETIN CARDIAC AMYLOIDOSIS

Abstract Aims The prognostic role of bone tracer uptake in transthyretin cardiac amyloidosis (ATTR-CA) is controversial. The study investigated the potential prognostic significance of biventricular (BiV) uptake in ATTR-CA. Methods Consecutive ATTR-CA patients who had cardiac scintigraphy with acquisition of planar and single-photon emission computed tomography (SPECT) images from the National Amyloidosis Centre (NAC) and four Italian centres were included. Planar BiV uptake was defined in presence of right ventricle (RV) uptake and graded in combination with SPECT imaging. The primary outcome was all-cause mortality. Results Among 1422 patients with ATTR-CA, BiV uptake was found in 85% of cases on planar scintigraphy and in 100% of cases on SPECT images. During a median follow-up of 39 months, BiV uptake at planar scintigraphy was associated with a higher all-cause mortality compared to isolated LV uptake (40.5% vs 10.7%, p&amp;lt;0.001), whereas the Perugini scale was not (p=0.27 in grade 2 vs 3). At multivariable analysis, RV uptake at planar scintigraphy leading to BiV uptake (HR 2.80, p=0.001), together with higher age at diagnosis (HR 1.03, p=0.001), V122I TTR variant (HR 1.60, p=0.001), NAC ATTR Stage (HR 1.29, p=0.003), E/e’ (HR 1.02, p=0.044), right atrium area index (HR 1.04, p=0.018) and GLS (HR 1.05, p=0.003) were independently associated with all-cause death. At time-dependent ROC curve analysis, the addition of planar BiV uptake to the NAC stage resulted in improved accuracy of the model for prediction of all-cause death (from AUC 0.74 to 0.79; p&amp;lt;0.001). Conclusions Planar RV uptake leading to BiV uptake identified ATTR-CA patients with worse outcome, potentially serving as a novel prognostic marker.

Impact of CT tube-voltage and bone density on the quantitative assessment of tracer uptake in Tc-99m bone SPECT/CT: A phantom study

PurposeTo evaluate the effect of computed tomography (CT) tube voltage and CT density for CT-based attenuation correction (CTAC) on quantification of tracer uptake in single photon emission computed tomography (SPECT)/CT. MethodsA cylindrical phantom contained 7 cylinders with diameter of 30 mm. The central cylinder and background part were filled with 17 kBq/ml of 99mTc-pertechnetate solution. Of the remaining 6 cylinders, one cylinder was filled with water and 5 cylinders were filled with each own different concentration of K2HPO4 solution (120, 275, 450, 666, and 960 mg/cm3) to simulate different bone densities. The 6 cylinders also contained 99mTc-pertechnetate solution with the same radioactivity concentration (207 kBq/ml). CT scans were performed with 4 different tube voltages of 80, 100, 120, and 140 kVp for CTAC. The radioactivity concentration in the 6 cylinders were measured on the SPECT images processed with 4 different attenuation coefficient maps derived from each tube voltage of CT images. ResultsCompared with the water cylinder without K2HPO4 solution, the measured radioactivity of the highest density cylinder (K2HPO4 solution concentration: 960 mg/cm3) was found to be overestimated by 3.3 % and 4.3 %, respectively, when the tube voltage was 120 kVp and 140 kVp (p = 0.022). The use of low-tube voltage, such as 80 kVp, has improved the quantitative accuracy of bone SPECT/CT. ConclusionsSPECT quantitative evaluation of tracers in high-density objects tends to overestimate as tube voltage for CTAC increases. However, the overestimation in quantitative SPECT/CT evaluation in simulated bone area is less than 5% at most.

Prognostic implications of biventricular uptake of bone tracers at planar scintigraphy in transthyretin cardiac amyloidosis

Abstract Background The prognostic role of bone tracer uptake in transthyretin cardiac amyloidosis (ATTR-CA) is controversial. A further characterization of cardiac retention measured by Perugini scale with differentiation between biventricular (BiV) and isolated left ventricle (LV) uptake has never been attempted previously. Purpose The study investigated the potential prognostic significance of BiV uptake in ATTR-CA. Methods In this multicentre, observational study, we analysed data of ATTR-CA patients who underwent bone tracer scintigraphy with acquisition of both planar and single photon emission computed tomography (SPECT) imaging. Cardiac uptake was defined according to the Perugini visual scale. Planar BiV uptake was defined according to right ventricle (RV) uptake: 0= absent, 1= &amp;lt; bone, 2= equal to bone, and 3= &amp;gt; bone and confirmed by SPECT imaging. The primary outcome was a composite of cardiac death or hospitalization for heart failure. The secondary outcome was all-cause mortality. Results All 124 ATTR-CA patients enrolled had LV and RV free wall uptake on SPECT images. Of them, 93 (75%) had BiV uptake visible on planar scintigraphy. BiV uptake was found in 14%, 70%, and 92% of Perugini grade 1, 2 and 3 respectively. Compared to those with isolated LV uptake, patients with BiV uptake were older (81 vs 77 years, p=0.006) and more frequently in NYHA≥3 (32% vs 10%, p=0.018). During a median follow-up of 21 months, BiV uptake was associated with a greater occurrence of the primary outcome compared to isolated LV uptake (40% vs 19%, p=0.021), whereas the Perugini scale was not (p=0.2) (Figure 1). At multivariable analysis, NYHA class ≥3 (hazard ratio [HR] 8.1, p=0.007), eGFR &amp;lt;60 ml/min (HR 2.1, p=0.025) and higher degree of RV uptake (HR 1.69, p=0.007) emerged as independent prognostic parameters. In an external cohort of 463 ATTR-CA patients with a median follow-up of 30 months, planar BiV uptake was independently associated with all-cause mortality, with an incremental risk in higher grades of RV uptake (p&amp;lt;0.001) (Figure 1). Conclusions The presence of BiV uptake at planar scintigraphy identified ATTR-CA patients with worse cardiovascular and global outcomes (Figure 2), potentially serving as a novel prognostic marker. Funding Acknowledgement Type of funding sources: None.

Quantitative 99mTc-DPD-SPECT/CT assessment of cardiac amyloidosis

IntroductionTransthyretin (ATTR) amyloidosis is responsible for the majority of cardiac amyloidosis (CA) cases and can be reliably diagnosed with bone scintigraphy and the visual Perugini score. We aimed to implement a quantification method of cardiac amyloid deposits in patients with suspected cardiac amyloidosis and to compare performance to visual scoring. Methods and materials136 patients received 99mTc-DPD-bone scintigraphy including SPECT/CT of the thorax in case of suspicion of cardiac amyloidosis. Imaging phantom studies were performed to determine the scaling factor for standardized uptake value (SUV) quantification from SPECT/CT. Myocardial tracer uptake was quantified in a whole heart volume of interest. ResultsForty-five patients were diagnosed with CA. A strong relationship between cardiac SUVmax and Perugini score was found (Spearman r 0.75, p < 0.0001). Additionally, tracer uptake in bone decreased with increasing cardiac SUVmax and Perugini score (p < 0.0001). ROC analysis revealed good performance of the SUVmax for the detection of ATTR-CA with AUC of 0.96 ± 0.02 (p < 0.0001) with sensitivity 98.7% and specificity 87.2%. ConclusionWe demonstrate an accessible and accurate quantitative SPECT approach in CA. Quantitative assessment of the cardiac tracer uptake may improve diagnostic accuracy and risk classification. This method may enable monitoring and assessment of therapy response in patients with ATTR amyloidosis.

Dual Targeting of Integrin αvβ3 and Neuropilin-1 Receptors Improves Micropositron Emission Tomography Imaging of Breast Cancer.

The receptors neuropilin-1 (NRP-1) and integrin αvβ3 are overexpressed in breast cancer and associated with neovascularization. We synthesized a heterodimeric tracer, 68Ga-DOTA-RGD-ATWLPPR, which simultaneously targets integrin αvβ3 and NRP-1 in breast cancer. In this study, we evaluated the diagnostic efficacy of 68Ga-DOTA-RGD-ATWLPPR during micropositron emission tomography (microPET)/X-ray computed tomography (CT) imaging and gamma counting. We evaluated the receptor-binding characteristics and tumor-targeting efficacy of the tracer in vitro and in vivo. Static microPET/CT imaging and gamma counting studies showed that 68Ga-DOTA-RGD-ATWLPPR uptake in MCF-7 tumors is higher than that of monomeric tracers. 68Ga-DOTA-RGD-ATWLPPR uptake could be blocked with excess unlabeled RGD or ATWLPPR, demonstrating the sensitivity and specificity of the tracer. We did not observe bone tracer uptake in vivo, but the data indicated that 68Ga-DOTA-RGD-ATWLPPR is metabolized in the kidneys and the liver uptake is low. In conclusion, 68Ga-DOTA-RGD-ATWLPPR has improved binding affinity, targeting efficiency, and tumor retention time when compared to monomeric tracers, suggesting that it has potential as an imaging probe for breast cancer detection.

SPECT/CT Assessment of In-Vivo Loading of the Knee Correlates with Polyethylene Deformation in Retrieved Total Knee Arthroplasty.

Background: SPECT/CT distribution patterns in patients with total knee replacements have previously been correlated with factors such as time of implantation, implant type and alignment. It is unknown, however, if an increased and more extended bone tracer uptake (BTU) in SPECT/CT, representing loading of the joint, correlates with findings from retrieval studies. The aim of this study was to further understand this subject. Materials and Methods: 62 retrieved TKA were included. SPECT/CT was performed prior to revision. Quantitative and qualitative medio-lateral comparisons of BTU intensity and distribution in the tibia were performed. Retrieval analysis was performed with a micro-CT method to assess the thickness differences between medial and lateral sides of polyethylene inserts with symmetrical designs. Results: In the subgroup of TKA with asymmetrical SPECT/CT distribution, there was a significant correlation between retrieval and medical imaging data (p = 0.0355): patients showing a more extended BTU in the medial compartment also had a significantly thinner insert in the medial compartment, and vice versa in the lateral side. Conclusion: This is the first study comparing BTU distribution patterns and retrieval findings. Our results support the hypothesis that SPECT/CT is able to identify bone activity due to implant position and loading.

Under-correction of preoperative varus alignment does not lead to a difference in in-vivo bone loading in 3D-SPECT/CT compared to neutral alignment

BackgroundThe aim was to investigate the correlation of bone tracer uptake (BTU) in SPECT/CT and changes in coronal knee alignment after total knee arthroplasty (TKA). We questioned if undercorrection of preoperative varus alignment leads to a difference in BTU compared to neutral alignment. MethodsConsecutive 66 patients who received SPECT/CT before and after TKA were retrospectively included. Adjusted mechanical alignment was the alignment target. The alignment of the knee was measured on 3D-CT by selecting standardized landmarks. Maximum (mean ± SD) and relative BTU (ratio to the reference) were recorded using a previously validated localization scheme (p < 0.05). ResultsIn the native group, 20 knees were aligned (30.3%) in valgus (HKA > 181.5°), 12 (18.2%) in neutral (178.5°-181.5°) and 34 (51.5%) in varus (HKA < 178°). Overall TKA changed the alignment towards neutral. 48.5% remained in the same groups, whereas 50% of native valgus and 33% of varus knees changed to neutral after TKA. In native varus alignment mean BTU was significantly higher in some medial tibial and femoral regions (fem1ia (p = 0.010), fem1ip (p = 0.002), tib1a.mid (p = 0.005), tib1a.tray (p = 0.000), tib1p.tray (p = 0.000)); in native valgus alignment mean BTU was higher in the corresponding lateral tibial and femoral regions (fem2ip (p = 0.001), tib2a.tray (p = 0.011), tib2p.tray (p = 0.002)). After TKA, a significant decrease in femoral and tibial BTU (femoral preoperative BTU 1.64 +/-0.69; femoral postoperative BTU 0.95 +/-0.42; p = 0.000// tibial preoperative BTU 1.65 +/- 0.93; tibial postoperative BTU 1.16 +/- 0.48; p = 0.000) and an increase in patellar BTU was observed (p = 0.025). Native varus alignment correlated with a higher medial BTU decrease medially. Undercorrection of preoperative varus alignment showed no higher BTU after TKA. ConclusionPreoperative varus alignment correlated with a higher decrease in BTU in specific femoral and tibial medial regions. Preoperative valgus alignment correlated with a higher decrease in the corresponding lateral regions. Undercorrection of preoperative varus alignment did not lead to higher bone loading reflected by BTU after TKA.

Does postoperative quantitative bone scintigraphy reflect outcomes following medial open-wedge high tibial osteotomy?

PurposeThe present study evaluated changes in bone tracer uptake (BTU) after medial open-wedge high tibial osteotomy (MOWHTO) and determined whether postoperative BTU correlates with clinical symptoms, radiologic parameters, or cartilage regeneration following MOWHTO.MethodsA total of 210 knees underwent MOWHTO for medial compartmental osteoarthritis (OA) were enrolled in this study. Mean follow-up period was 42.7 months. We assessed BTU for the medial compartment of the knee before MOWHTO and at the time of plate removal. Radiologic parameters included Kellgren-Lawrence (K-L) grade and Hip-Knee-Ankle angle (HKAA). Clinical evaluation included American Knee Society (AKS) score and cartilage status was graded at the time of MOWHTO and second-look arthroscopy according to the International Cartilage Repair Society (ICRS) grading system and articular cartilage regeneration stage. Statistical analysis performed to assess the relationships among postoperative BTU of the medial compartment, radiologic parameters, arthroscopic changes and clinical outcomes.ResultsBTU of medial femoral condyle and tibial plateau were significantly decreased at 2 years after MOWHTO (p<0.001). AKS scores and arthroscopic cartilage status were also significantly improved following MOWHTO. BMI and postoperative HKAA showed significant correlations with postoperative changes of BTU in uni- and multi-variable analysis. Meanwhile, postoperative changes of BTU did not show significant correlation with clinical outcomes or cartilage regeneration following MOWHTO.ConclusionLower BMI and postoperative valgus alignment were significant predictor for postoperative BTU decrease of the medial compartment following MOWHTO. However, postoperative changes of BTU did not reflect cartilage regeneration or clinical outcomes until the midterm follow-up.

Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome

PurposeThe purpose of this study was to investigate whether specific bone tracer uptake (BTU) patterns on preoperative SPECT/CT could predict which patients with varus alignment and medial overload would particularly benefit from medial opening-wedge high tibial osteotomy (MOWHTO). It was the hypothesis that an increased preoperative BTU relative to the reference BTU of the femur on SPECT/CT in the lateral and patellar compartments of the knee are predictive factors for inferior clinical outcome and that the clinical outcome correlates with the extent of alignment correction.MethodsTwenty-three knees from 22 patients who underwent MOWHTO for medial compartment overload were investigated preoperatively using Tc-99m-SPECT/CT. BTU was quantified and localised to specific joint areas according to a previously validated scheme. Pre- and postoperative mechanical alignment was measured. Clinical outcome was assessed at a median of 24 months (range 11–30) after MOWHTO by collecting the WOMAC score.ResultsSignificant correlations between BTU in the patellar area and the total WOMAC score and its subcategories pain and stiffness were found. Thus, BTU in the 1sPat area (superior lateral patellar compartment) correlated with total WOMAC (rho = 0.43, p = 0.04), pain subcategory (rho = 0.43, p = 0.04), and stiffness subcategory (rho = 0.59, p = 0.003). No significant correlations were found between alignment correction, age, gender and WOMAC.ConclusionThis study highlights the role of preoperative SPECT in modern knee surgery to obtain information about the loading pattern on different compartments of the knee. Despite the limited number of participants, the present study shows that a preoperative SPECT/CT scan can help the treating surgeons to identify patients who may be at risk of inferior clinical outcome if an MOWHTO is considered, as an elevated BTU in the patellar region on preoperative SPECT/CT appears to be a potential risk factor for postoperative pain and stiffness.Level of evidenceLevel III.

The use of SPECT/CT quantification of 99mTc-PYP uptake to assess tafamidis treatment response in ATTR cardiac amyloidosis

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Nuclear scintigraphy with bone-avid radiotracers such as Tc-99m-PYP, Tc99m-DPC and Tc-99m-HMDP are used to diagnose transthyretin (ATTR) cardiac amyloidosis with limited quantification employing a semi-quantitative visual score and a heart to contralateral lung ratio. Therapy for ATTR cardiac amyloid currently is limited to a single FDA approved agent, tafamidis, however, there is no data regarding the longitudinal assessment of imaging findings in patients undergoing therapy. SPECT/CT acquisition and analysis with dedicated software can provide volumetric assessment and quantification of cardiac tracer uptake. Purpose The purpose of this study was to perform longitudinal assessment of cardiac ATTR amyloid 99mTc-PYP imaging findings to determine if treatment with tafamidis results in any change in quantitative measures of tracer uptake. There is no data on if treatment results in a decrease in cardiac amyloid burden as assessed by 99mTc-PYP imaging. Methods A prospective, single center, study of patients with ATTR cardiac amyloid being treated with tafamidis (either 80mg or 61mg dose) who have baseline and follow-up 99mTc-PYP studies. SPECT/CT quantification software was used to quantify heart, lung, and bone tracer uptake and generate standardized uptake values (SUVs). Comparison of baseline (before treatment) total SUVs, mean SUV value, percentage of the injected dose, mean SUV of heart to mean SUV of bone ratio and to mean SUV of right lung ratio was made to the values obtained at follow-up after tafamidis treatment. Measurements were obtained from the whole heart and the isolated left ventricle. Data was obtained by two physicians and the results averaged. Results 5 patients were analyzed with a mean age 73.8 ± 7.7, 80% were males, and a mean length of tafamidis therapy at repeat imaging of 12.5 ± 3.8 months. At follow-up there was an average decrease in whole heart total SUV counts by -25.9 ± 10.3%, in the mean SUV value by -18.2 ± 18.2% and in the percentage of injected dose by -23.7 ± 14.0%. Similar decreases were seen in the isolated left ventricle measures. Heart to bone and heart to lung ratios showed a mixed response to therapy. Detailed results are provided in the table. Conclusion The measurements of total SUV counts, mean SUV value, and percentage of the injected dose showed improvement with tafamidis treatment. The ratios did not uniformly show improvement and the reason for this finding is unclear. This new technique offers a potential method for following tafamidis therapy and assessing the cardiac amyloid burden.

Correlations of typical pain patterns with SPECT/CT findings in unhappy patients after total knee arthroplasty

PurposeThe diagnostic process in patients after painful total knee arthroplasty (TKA) is challenging. The more clinical and radiological information about a patient with pain after TKA is included in the assessment, the more reliable and sustainable the advice regarding TKA revision can be. The primary aim was to investigate the position of TKA components and evaluate bone tracer uptake (BTU) using pre-revision SPECT/CT and correlate these findings with previously published pain patterns in painful patients after TKA.MethodsA prospectively collected cohort of 83 painful primary TKA patients was retrospectively evaluated. All patients followed a standardized diagnostic algorithm including 99m-Tc-HDP-SPECT/CT, which led to a diagnosis indicating revision surgery. Pain character, location, dynamics and radiation were systematically assessed as well as TKA component position in 3D-CT. BTU was anatomically localized and quantified using a validated localization scheme. Component positioning and BTU were correlated with pain characteristics using non-parametric Spearman correlations (p < 0.05).ResultsBased on Spearman’s rho, significant correlations were found between pain and patients characteristics and SPECT/CT findings resulting in nine specific patterns. The most outstanding ones include: Pattern 1: More flexion in the femoral component correlated with tender/splitting pain and patella-related pathologies. Pattern 3: More varus in the femoral component correlated with dull/heavy and tingling/stinging pain during descending stairs, unloading and long sitting in patients with high BMI and unresurfaced patella. Pattern 6: More posterior slope in the tibial component correlated with constant pain.ConclusionThe results of this study help to place component positioning in the overall context of the "painful knee arthroplasty" including specific pain patterns. The findings further differentiate the clinical picture of a painful TKA. Knowing these patterns enables a prediction of the cause of the pain to be made as early as possible in the diagnostic process before the state of pain becomes chronic.Level of evidenceLevel III

Subchondral Bone Condition and Intraoperative Grading of Cartilage Degeneration Underneath Patella Unrelated to the Clinical Outcome after TKA with Unresurfaced Patella.

The degree of cartilage degeneration assessed intraoperatively may not be sufficient as a criterion for patellar resurfacing in total knee arthroplasty (TKA). However, single-photon emission tomography/computed tomography (SPECT/CT) is useful for detecting osteoarthritic involvement deeper in the subchondral bone. The purpose of the study was to determine whether SPECT/CT reflected the cartilage lesion underneath the patella in patients with end-stage osteoarthritis (OA) and whether clinical outcomes after TKA without patellar resurfacing differed according to the severity of patellofemoral (PF) OA determined by visual assessment and SPECT/CT findings. This study included 206 knees which underwent TKA. The degree of cartilage degeneration was graded intraoperatively according to the International Cartilage Repair Society grading system. Subjects were classified into low and high uptake groups according to the degree of bone tracer uptake (BTU) on SPECT/CT in the PF joint. The Feller's patella score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed preoperatively and postoperative 1 and 2 years. The increased BTU in the PF joint was associated with more severe degenerative cartilage changes underneath the patella (p < 0.001). The risk for the presence of denudated cartilage was greater in the high uptake group (odds ratio = 5.89). There was no association between clinical outcomes and visual grading of patellar cartilage degeneration or the degree of BTU on SPECT/CT. The visual assessment of the degree of cartilage degeneration underneath the patella and preoperative SPECT/CT evaluation of the PF joint were not predictive of clinical outcome after TKA with unresurfaced patella.

Meniscus Tear Presented as Bone Marrow Edema Manifested in Hybrid Images in Skeletal Scintigraphy: A Case Report

Chronic knee pain is a common degenerative disorder amongst the elderly, and differential diagnosis through imaging remains crucial. Bone marrow edema represents an increase of water content in the normally fatty bone marrow. The size of the bone marrow edema is associated with the development of knee pain in Osteoarthritis (OA). Bone marrow edema cannot be seen on plain radiography, and while a SPECT/CT scan is more sensitive than MRI in detection of bone marrow edema, the definite diagnosis of bone marrow edema is dependent upon MRI. SPECT/CT is the combination of 3D scintigraphy and computed tomography, which provides more specific anatomical localization and improved sensitivity. It is a valuable tool for the early evaluation of knee pain, as the increase of bone tracer uptake can be seen in bone marrow edema (BME), cartilage lesions, meniscus tear or derangement and valgus/varus alignment. Hence acquiring information from both MRI and SPECT/CT can help determine the optimal treatment. We present a case of chronic knee pain as evaluated by MRI and SPECT/CT.

Meniscus Tear Presented as Bone Marrow Edema Manifested in Hybrid Images in Skeletal Scintigraphy: A Case Report

Chronic knee pain is a common degenerative disorder amongst the elderly, and differential diagnosis through imaging remains crucial. Bone marrow edema represents an increase of water content in the normally fatty bone marrow. The size of the bone marrow edema is associated with the development of knee pain in Osteoarthritis (OA). Bone marrow edema cannot be seen on plain radiography, and while a SPECT/CT scan is more sensitive than MRI in detection of bone marrow edema, the definite diagnosis of bone marrow edema is dependent upon MRI. SPECT/CT is the combination of 3D scintigraphy and computed tomography, which provides more specific anatomical localization and improved sensitivity. It is a valuable tool for the early evaluation of knee pain, as the increase of bone tracer uptake can be seen in bone marrow edema (BME), cartilage lesions, meniscus tear or derangement and valgus/varus alignment. Hence acquiring information from both MRI and SPECT/CT can help determine the optimal treatment. We present a case of chronic knee pain as evaluated by MRI and SPECT/CT.

No reduced patellar loading with latest-generation cruciate-retaining total knee arthroplasty\u2014a comparative study of Attune and Press-Fit Condylar\xae

PurposeTo investigate if the latest-generation cruciate-retaining total knee arthroplasty (CR-TKA) systems through more patella-friendly femoral trochlea reduce the patellar bone loading.MethodsTwenty patients who underwent Attune CR-TKA were matched with twenty-one patients who underwent Press-Fit Condylar® (PFC) CR-TKA. The patella was always preserved. The in vivo patellar loading was measured twice by two blinded observers and localised on an 8-quadrant grid on 1-year post-operatively SPECT/CT images. The position of the TKA components, patella height, thickness, tilt, and tibial tuberosity-trochlear groove index were measured in 3D CT. Knee function was assessed pre-operatively, at 12 and 24 months post-operatively with the knee society score (KSS). All data were compared between groups with the Mann-Whitney U test and within groups with Spearman’s correlation.ResultsA significantly higher bone tracer uptake (BTU) was seen in the Attune group in the lateral non-articular patellar quadrants. No other significant differences of the BTU were seen. The post-operative KSS did not differ significantly. Spearman’s correlation showed no correlations between the significantly higher BTU of the lateral non-articular patellar quadrants and the position of the TKA and patellar measurements. All patellar measurements did not correlate with bone stress in SPECT/CT.ConclusionNo significant improvement in terms of in vivo patellar bone stress was seen with the latest-generation CR-TKA system. The increased bone stress at the non-articular lateral patellar quadrants of the Attune could be due to higher stabilising quadriceps forces.