Diagnostic accuracy of SPECT/CT arthrography in patients with suspected aseptic joint prostheses loosening.

PURPOSE: To evaluate the diagnostic accuracy of SPECT/CT arthrography in patients with suspected aseptic prosthesis loosening following hip and knee arthroplasty. METHODS: A retrospective review of 63 SPECT/CT arthrogram studies (36 knees and 27 hips) between February 1, 2013, and July 1, 2018, was conducted. All patients underwent clinical and radiologic evaluation as part of their assessment for persistent pain following hip and knee arthroplasty. The detection of tracer activity along the bone-prosthetic interface on SPECT/CT suggests aseptic loosening. Operative assessment as well as clinical/radiologic follow-up at a minimum of 1 year was used as the reference standard. RESULTS: The sensitivity and specificity of SPECT/CT for detection of aseptic loosening was 6/7 (86%) and 55/56 (98%), respectively. This gives a positive predictive value (PPV) of 6/7 (86%), a negative predictive value (NPV) of 55/56 (98%), and a diagnostic accuracy of 61/63 (97%). CONCLUSION: SPECT/CT arthrography has a high diagnostic accuracy (97%) in the evaluation of loosening of both hip and knee arthroplasties in patients with persistent post-procedural pain.

Utility of FDG PET and Cardiac MRI in Diagnosis and Monitoring of Immunosuppressive Treatment in Cardiac Sarcoidosis.

PURPOSE: To compare the contributions of cardiac MRI and PET in the diagnosis and management of cardiac sarcoidosis (CS), with particular reference to quantitative measures. MATERIALS AND METHODS: This is a retrospective, observational study of 31 patients (mean age, 45.7 years) with proven extracardiac sarcoidosis and possible CS who were investigated with fluorine 18 fluorodeoxyglucose (FDG) PET/CT and cardiac MRI. Patients were treated at physicians' discretion with repeat combined imaging after an interval of 102-770 days (median, 228 days). RESULTS: Significant myocardial FDG uptake was shown on visit 1 (myocardial maximum standardized uptake value [SUVmax] > 3.6) in 17 of 22 patients who were subsequently treated. Myocardial SUVmax decreased at follow-up (6.5 to 4.0; P < .01) and was matched by significant decreases in FDG-avid lung and mediastinal node disease. A volumetric measure of myocardium above a threshold SUV (cardiac metabolic volume) decreased from a mean of 42.5 to a mean of 4.1 (P < .001). This was associated with significant improvement in the left ventricular ejection fraction (LVEF) (45.8 increasing to 50.9; P < .031). There was no change in volume of late gadolinium enhancement at treatment. Patients who were untreated showed no change in any FDG PET or cardiac MRI parameter. CONCLUSION: Myocardial FDG uptake in patients suspected of having CS is presumed to represent active inflammation. When treated with corticosteroids, this resolved or regressed at follow-up, with an improvement in LVEF and FDG-avid thoracic disease. Patients who were untreated showed no change in any parameter. Quantification of FDG-avid myocardium using cardiac metabolic volume is proposed as a useful objective measure for assessing response to therapy.© RSNA, 2020See also commentary by Gutberlet in this issue.

Quantitative blood flow evaluation of vasodilation-stress compared with dobutamine-stress in patients with end-stage liver disease using 82Rb PET/CT.

BACKGROUND: Our aim was to determine if end-stage liver disease (ESLD) is associated with an attenuated response to vasodilator-stress or dobutamine-stress using 82Rb-PET MPI with blood flow quantification. METHODS AND RESULTS: Pre-liver transplant patients who had a normal dipyridamole-stress (n = 27) or dobutamine-stress (n = 26) 82Rb PET/CT MPI study with no identifiable coronary artery calcium were identified retrospectively and compared to a prospectively identified low-risk of liver disease dipyridamole-stress control group (n = 20). The dipyridamole-stress liver disease group had a lower myocardial flow reserve (MFR) (1.89 ± 0.79) than the control group (2.79 ± 0.96, P < .05). The dobutamine-stress group had a higher MFR than both other groups (3.69 ± 1.49, P < .05). A moderate negative correlation between MELD score and MFR was demonstrated for the dipyridamole-stress liver disease group (r = - 0.473, P < .05). This correlation was not observed for the dobutamine-stress liver disease group (r = - 0.253, P = .21). The liver failure group as a whole (n = 53) had a higher resting myocardial blood flow (0.97 ± 0.33 mL/min/g) than the control group (0.82 ± 0.26, P < .05). CONCLUSION: Dipyridamole demonstrates an attenuated vasodilatory response in ESLD patients compared to a non-ESLD control group related to higher resting blood flow and comparatively reduced stress blood flow. Dobutamine does not demonstrate this effect implying it may be the preferred pharmacologic MPI stress agent for ESLD patients.

Bone and Gallium Single-Photon Emission Computed Tomography-Computed Tomography is Equivalent to Magnetic Resonance Imaging in the Diagnosis of Infectious Spondylodiscitis: A Retrospective Study.

OBJECTIVES: Spondylodiscitis has historically been a difficult clinical diagnosis. Two imaging techniques that address this problem are magnetic resonance imaging (MRI) and combined bone (99mTc-methylene diphosphonate) and gallium-67 single-photon emission computed tomography-computed tomography (SPECT-CT). Their accuracies have not been adequately compared. The purpose of this study is to compare the sensitivities and specificities of bone and gallium SPECT-CT and MRI in infectious spondylodiscitis. METHODS: This retrospective study assessed all patients who underwent a bone or gallium SPECT-CT of the spine to assess for infectious spondylodiscitis from January 1, 2010, to May 2, 2012, at a single tertiary care centre. Thirty-four patients (23 men; average 62 ± 14 years of age) were included. The results of the bone or gallium SPECT-CT were compared against MRI for all patients in the cohort who underwent an MRI within 12 weeks of the SPECT-CT. A diagnosis of spondylodiscitis in the discharge summary was considered the reference standard, and was based on a combination of clinical scenario, response to therapy, imaging, or microbiology. RESULTS: Spondylodiscitis was diagnosed in 18 patients and excluded in 16. Bone or gallium SPECT-CT and MRI had similar (P > .05; κ = 0.74) sensitivities (0.94 vs 0.94), specificities (1.00 vs 1.00), positive predictive values (1.00 vs 1.00), negative predictive values (0.94 vs 0.80), and accuracies (0.97 vs 0.95) when compared to the reference standard. CONCLUSION: Although MRI remains the initial modality of choice in diagnosing spondylodiscitis, bone and gallium SPECT-CT appears diagnostically equivalent and should be considered a viable supplementary or alternative imaging modality particularly if there is contraindication or inaccessibility to MRI.

Validation of metabolic tumor volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery.

BACKGROUND: Despite the promise of metabolic tumor volume (MTV) as a risk-stratifying marker, the retrospective design of the initial study limits its generalizability. Therefore, this study sought to validate MTV as a prognostic factor for oral cavity squamous cell carcinoma (OCSCC) treated with primary surgery within an independent data set. METHODS: The validation data set consisted of 42 patients diagnosed with OCSCC between 2008 and 2012. The original cohort consisted of 80 patients. MTV and SUVmax were calculated for the primary tumor and nodal metastasis separately, as well as combined. Before statistical analysis, MTV and SUVmax values were divided into intertertile thirds to allow for intergroup survival analysis. Validation analysis was conducted on the validation data set alone. Data from both cohorts were then combined (n=122) to increase statistical power. RESULTS: An increase in combined MTV of 17.5cm(3) was associated with statistically significant increase in risk of disease recurrence (HR=19.2, p<0.001) and death (HR=9.2, p<0.05). Combined SUVmax failed to predict overall (HR=1.0, p>0.05) and disease-free survival (HR=1.0, p>0.05). Increase in the MTV of the primary tumor was associated with an increase in the risk of disease recurrence (HR=21.7, p=0.0001) and risk of death (HR=7.0, p=0.0001), while increase in the MTV of the locoregional neck metastasis was not (p>0.05). An MTV cutoff value of greater than 10.2cm(3) was found to significantly affect survival. CONCLUSION: Due to the reproducibility of MTV findings, this study validates MTV as an independent prognostic factor for OCSCC treated with primary surgery.

Accuracy of Dual Phase Single-Photon Emission Computed Tomography/Computed Tomography in Primary Hyperparathyroidism: Correlation With Serum Parathyroid Hormone Levels.

PURPOSE: The objectives of this study were: 1) to determine the accuracy of dual-phase (99m)Tc -methoxyisobutylisonitrile (MIBI) with single-photon emission computed tomography/computed tomography (SPECT/CT) for the preoperative localization of parathyroid adenomas in the setting of primary hyperparathyroidism; 2) to determine the accuracy of localization for ectopic glands; and 3) to assess the relationship between accuracy and serum parathyroid hormone (PTH) levels. METHODS: Eighty-eight patients who underwent (99m)Tc-MIBI SPECT/CT imaging for primary hyperparathyroidism at our institution over a 27-month period were retrospectively assessed. The preoperative SPECT/CT results were compared to intraoperative findings (within 1 year of imaging). The relationship between serum PTH level (within 3 months) and SPECT/CT accuracy was then evaluated. RESULTS: Accuracy indices for the retrothyroid subgroup were sensitivity 86.7%, specificity 96.4%, positive predictive value 98.1%, negative predictive value 77.1%, and accuracy 89.8%. Accuracy indices for ectopic parathyroid adenomas were sensitivity 81.5%, specificity 100%, positive predictive value 100%, negative predictive value 92.4%, and accuracy 94.3%. For the overall group, SPECT/CT demonstrated a sensitivity of 85.1% and a PPV of 98.7%. SPECT/CT correctly identified the abnormal parathyroid gland in 60% of patients with a normal serum PTH (<6.9 pmol/L), 73% between 6.9-9.9 pmol/L, 86% between 10.0-14.9 pmol/L, 100% between 15.0-19.9 pmol/L, 88% between 20.0-24.5 pmol/L, and 100% of patients with a PTH greater than 25.0 pmol/L. CONCLUSIONS: Dual-phase (99m)Tc- MIBI with SPECT/CT is an accurate and reliable means to correctly localize both retrothyroid and ectopic parathyroid adenomas for the purpose of surgical planning. The accuracy of SPECT/CT increases with increasing serum PTH levels.

The Accuracy of Single Photon Emission Computed Tomography/Computed Tomography Arthrography in Evaluating Aseptic Loosening of Hip and Knee Prostheses.

Aseptic loosening represents the most common complication associated with hip and knee arthroplasty and is a common indication for surgical revision in the post-arthroplasty population. The optimal imaging methodology in evaluating clinical suspected loosening is not well-defined. Our study retrospectively evaluated nuclear medicine arthrography with hybrid single photon emission computed tomography/computed tomography (SPECT/CT) in 38 patients (21 hip, 17 knee) compared with reference standards of surgical evaluation, spontaneous resolution of symptoms without revision, or a minimum of 1 year clinical and radiographic follow-up. Our study demonstrated a sensitivity of 100%, specificity of 96.0%, PPV of 92.9%, NPV of 100%, and accuracy of 97.4% with this imaging technique suggesting utility of nuclear medicine arthrography with SPECT/CT in the clinical evaluation of suspected aseptic loosening.

Prostate perfusion mapped by technetium-99m macroaggregated albumin after selective arterial injection.

PURPOSE: To determine if perfusion of the prostate can be mapped using technetium-99m ((99m)Tc) macroaggregated albumin (MAA) after selective prostate artery catheterization. MATERIALS AND METHODS: Selective prostate artery injections of MAA were performed and analyzed in 14 patients; 9 patients received unilateral injection, and 5 patients received bilateral injections (37 MBq/1 mCi per injection). Fused single-photon emission computed tomography/computed tomography (SPECT/CT) images were subsequently acquired using a fiducial marker technique. Perfusion distribution was assessed, and relative intraprostatic versus extraprostatic activity was quantified and compared between groups. RESULTS: The percentage of the prostate gland containing activity was significantly greater for the bilateral injection group compared with the unilateral injection group (76.6% vs 44.3%, P < .05). The percentage of relative intraprostatic versus extraprostatic activity was significantly lower for the bilateral injection group compared with the unilateral injection group (40.3% vs 75.9%, P < .05). Sites of visualized extraprostatic activity included the seminal vesicles (8 of 14 patients), internal iliac vessels (7 of 14 patients), bladder wall (5 of 14 patients), space of Retzius (3 of 14 patients), rectal wall (3 of 14 patients), and penis (1 of 14 patients). CONCLUSIONS: Perfusion mapping with (99m)Tc-MAA can be effectively performed with SPECT/CT after selective prostate artery catheterization. The relative percentage of intraprostatic versus extraprostatic activity can be quantified, and the distribution of activity within and outside the prostate gland can be determined.

Metabolic tumour volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery.

BACKGROUND: Metabolic tumour volume (MTV) obtained from pre-treatment 18 F-fluorodeoxydeglucose positron emission tomography with computed tomography (PET-CT) has been validated as an independent predictive factor of outcomes in head and neck cancer patients (HNC) treated with primary chemoradiotherapy (CRT). However its role in patients treated with primary surgery has not yet been studied. OBJECTIVE: To evaluate the prognostic value of MTV in patients treated with primary surgery for oral cavity squamous cell carcinoma (OCSCC). METHOD: Demographic and survival data was obtained from patients diagnosed with OCSCC from 2008-2012 in Alberta, Canada. All patients included in the study had PET-CT scan before curative surgical resection. MTV and maximum standardized uptake value (SUVmax) value was delineated from pre-treatment PET-CT scans using Segami Oasis software (Columbus, OH). MTV and SUVmax were divided into intertertile thirds before statistical analysis to allow for in-group comparison of survival. RESULTS: A total of 80 patients were analyzed using SPSS ver. 20.0 (SPSS Inc, Chicago, IL). Five-year overall, and disease-free survival using Kaplan-Meier curves were 70% and 73% respectively. When the combined SUVmax (tumour primary and locoregional metastasis) was evaluated, it failed to predict overall (HR = 1.0, p = 0.99) or disease-free survival (HR = 1.0, p = 0.227). CONCLUSIONS: This study shows that MTV is an independent adverse prognostic factor for death and disease recurrence in OCSCC treated with primary surgery.

Streamlining the imaging of clinically suspected pheochromocytoma: using urine metanephrines to decrease imaging costs.

PURPOSE: To improve the cost efficiency of the imaging evaluation of clinically suspected pheochromocytoma by using 24-hour fractionated urine metanephrine (FUM) results. METHODS: A retrospective review of I-123 meta-iodo-benzyl-guanidine single photon emission tomography (SPECT) computed tomography (CT) studies performed at our institution between January 2007 and February 2011 for clinically suspected pheochromocytoma was performed. SPECT-CT results from 70 patients were compared with results from 24-hour FUM analysis (within 2 months of SPECT-CT) and with relevant CT or magnetic resonance imaging studies (within 6 months of SPECT-CT). An imaging algorithm was developed to maximize cost efficiency without altering the final imaging interpretation. Actual imaging costs for the studied cohort were compared with the expected costs if this algorithm had been applied. RESULTS: If the 24-hour FUMs were normal, then all the SPECT-CT studies were negative (16/70). Eighty-seven percent of patients with abnormal total metanephrine had a positive SPECT-CT. If the total metanephrine was normal but 1 or more of the metanephrine fractions were abnormal, then 39%-58% of the SPECT-CT studies were positive. Within this subgroup, none had a positive SPECT-CT if a CT or magnetic resonance image was negative or benign. The actual imaging costs averaged CAD$2833.19 per patient for this cohort. Applying a streamlined imaging algorithm guided by 24-hour FUM analysis would result in an average imaging cost of CAD$1225.97 per patient without an expected change in the final imaging impression. CONCLUSION: By using 24-hour FUM results to streamline imaging, considerable cost savings per patient (56.7%) can be attained without a change in the final overall imaging interpretation.

Lymphoscintigraphy in early-stage non-small cell lung cancer with technetium-99m nanocolloids and hybrid SPECT/CT: a pilot project.

OBJECTIVE: The goal of our study was to determine if lymph node activity could be visualized using a hybrid single-photon emission computed tomography/computed tomography (SPECT/CT) scanner with two commonly used colloidal lymphatic radiotracers--99mTc-antimony sulfide colloid (ASC) and 99mTc-filtered sulfur colloid (FSC) in the setting of low-stage non-small cell lung cancer (NSCLC). METHODS: Patients undergoing CT-guided percutaneous lung biopsies for clinically suspected early-stage lung cancer were randomized to peri-lesional injection of 37 MBq (0.5 mL) of either ASC or FSC. SPECT/CT of the thorax was performed at either 1, 2, or 3 h post-injection. The images were reviewed to determine if lymph node activity separate from the injection site could be identified. RESULTS: 24 patients were included. Lymph node activity was identified in 50% of patients. A total of 15 lymph nodes with activity were visualized including 5 ipsilateral hilar, 6 ipsilateral mediastinal, and 4 distant locations. No contralateral mediastinal or hilar activity was visualized. There was a tendency to improved visualization with ASC and the longer 3 h wait time. Most patients also demonstrated significant pleural, tracheobronchial, and/or systemic activity. CONCLUSIONS: SPECT/CT imaging can demonstrate lymph node activity separate from the injection site in at least some low-stage NSCLC patients with a perilesional injection of 99mTc nanocolloid tracers. Further investigation into the role of pre-operative lymphoscintigraphy with SPECT/CT in patients with lung cancer is warranted.

The clinical utility of a diagnostic imaging algorithm incorporating low-dose perfusion scans in the evaluation of pregnant patients with clinically suspected pulmonary embolism.

PURPOSE OF THE REPORT: The aim of this study was to determine the proportion of pregnant patients with a clinical suspicion of pulmonary embolism and a normal chest radiograph who require further evaluation with perfusion scintigraphy alone compared with both perfusion scintigraphy and computed tomography (CT). PATIENTS AND METHODS: All patients who had a low-dose perfusion lung scan as part of a clinical imaging algorithm to assess for clinically suspected pulmonary embolism in pregnant patients at 3 regional hospitals from September 2009 to February 2011 were retrospectively reviewed. The proportion of patients requiring a low-dose perfusion-only lung scan was compared with the proportion requiring further evaluation with both a low-dose perfusion scan and a CT scan to complete the algorithm. RESULTS: Seventy-four (74) patients were included. Sixty-one (61/74; 82.4%) patients had a normal low-dose perfusion-only scan and did not require further imaging. Thirteen (13/74; 17.6%) patients demonstrated an abnormal perfusion scan and required further imaging with a CT scan. One patient (1/74; 1.4%) was diagnosed with pulmonary embolism. CONCLUSIONS: Our results suggest that for pregnant patients with a normal chest radiograph, pulmonary embolism can be excluded in 82.4% of patients with a low-dose perfusion scan alone.

The clinical significance of incidental intra-abdominal findings on positron emission tomography performed to investigate pulmonary nodules.

BACKGROUND: Lung cancer is a common cause of cancer-related death. Staging typically includes positron emission tomography (PET) scanning, in which (18)F-fluoro-2-dexoy-D-glucose (FDG) is taken up by cells proportional to metabolic activity, thus aiding in differentiating benign and malignant pulmonary nodules. Uptake of FDG can also occur in the abdomen. The clinical significance of incidental intraabdominal FDG uptake in the setting of pulmonary nodules is not well established. Our objective was to report on the clinical significance of incidental intra-abdominal FDG activity in the setting of lung cancer. METHODS: Fifteen hundred FDG-PET reports for studies performed for lung cancer were retrospectively reviewed for the presence of incidental FDG-positive intraabdominal findings. Patient charts with positive findings were then reviewed and information extracted. RESULTS: Twenty-five patients (25/1500) demonstrated incidental intraabdominal FDG uptake thought to be significant (1.7%) with a mean patient age of 71 years. Colonic uptake was most common (n = 17) with 9 (52%) being investigated further. Of these 9 cases, a diagnosis of malignancy was made in 3 patients, pre-malignant adenomas in 2 patients, a benign lipoma in 1 patient and no abnormal findings in the remaining patients. 8 patients were not investigated further (3 diagnosed with metastatic lung cancer and 2 were of advanced age) secondary to poor prognosis. CONCLUSION: Incidental abdominal findings in the colon on FDG-PET scan for work-up of pulmonary nodules need to be further investigated by colonoscopy.

Effect of hepatic steatosis on liver FDG uptake measured in mean standard uptake values.

PURPOSE: To evaluate the association between diffuse fatty infiltration of the liver and average fluorine 18 fluorodeoxyglucose (FDG) uptake in the liver. MATERIALS AND METHODS: Institutional review board approval was obtained for this study; the requirement for informed patient consent was waived. Consecutive nonenhanced whole-body hybrid FDG positron emission tomographic (PET)-computed tomographic (CT) scans obtained in 142 patients (mean age, 63.6 years; age range, 19-94 years) from October 1, 2008, to November 28, 2008, were retrospectively reviewed. Mean attenuation (in Hounsfield units) and standardized uptake value (SUV) measurements for the liver and spleen were obtained, with identical regions of interest used for the CT and PET examinations. The patients were assigned to three study groups: a control group-119 patients with a mean liver attenuation value greater than or equal to the mean spleen attenuation value, a diffuse fatty liver disease group-23 patients in whom the mean liver attenuation value was less than the mean spleen attenuation value, and a more strictly defined fatty liver disease group-a subset of 10 patients from the diffuse fatty liver disease group with a mean liver attenuation value minus mean spleen attenuation value difference of less than or equal to -10 HU. Mean SUV (SUV(m)) values were compared between the groups by using a two-sample t test for means. The association between mean liver attenuation and average FDG uptake was assessed with linear regression analysis. RESULTS: The average SUV(m)for the control group was 2.18 (standard deviation [SD], 0.36; 95% confidence interval [CI]: 2.12, 2.24). No significant difference was identified when the average SUV(m)for the control group was compared with those for the fatty liver disease (SUV(m), 2.03; SD, 0.36; 95% CI: 1.90, 2.16) (P >.05) and more strictly defined fatty liver disease (SUV(m), 2.07; SD, 0.24; 95% CI: 1.92, 2.22) groups (P >.05). Linear regression analysis of liver SUV(m)as a function of mean liver attenuation revealed a mean slope of 0.005 (SD, 0.04; 95% CI: -0.005, 0.015) and a correlation coefficient of 0.02. CONCLUSION: No association between liver attenuation and FDG uptake measured in terms of SUV(m)was observed. On the basis of these data, it is acceptable to use the liver as a comparator for extrahepatic foci of equivocal increased FDG activity in patients with fatty liver disease. (c) RSNA, 2010.

99mTc-WBC scintigraphy with SPECT/CT in the evaluation of arterial graft infection.

OBJECTIVE: The goals of our study were to retrospectively review our experience in using Tc-white blood cell (WBC) single-photon emission computed tomography/computed tomography (SPECT/CT) imaging in the evaluation of possible arterial graft infection and to attempt to establish objective criteria for assessment. METHODS: Eleven Tc-WBC SPECT/CT studies performed for the evaluation of clinically suspected arterial graft infection were retrospectively reviewed and compared with reference outcomes. In an attempt to define objective criteria for interpretation, comparison was also made with background liver and bone marrow activity. RESULTS: When compared with reference outcomes, the subjective scan interpretations showed 6 of 11 true positives (TP), 4 of 11 true negatives (TN), and 1 of 11 false positive (FP). Using the liver as a comparator resulted in 4 of 10 TP, 5 of 10 TN, and 1 of 10 FN. Using the bone marrow as a comparator resulted in 3 of 10 TP, 5 of 10 TN, and 2 of 10 FN. In one patient neither the liver nor the bone marrow was in the field of view. CONCLUSION: These findings suggest a high accuracy for Tc-WBC SPECT/CT in assessing clinically suspected arterial graft infection. Furthermore, the liver may be the best objective comparator for standardized interpretation.