PURPOSE:To evaluate the robustness of the Hopkins criteria score (HCS) with regards to new PET reconstruction methods in therapy response assessment of head and neck cancer after (chemo)radiotherapy [(C)RT]. METHODS:Maximum standardized uptake value and HCS were retrospectively assessed on fluorine-18-deoxyglucose PET/computed tomography (CT) 12 weeks after (C)RT for neck lymph nodes and the primary tumor site in 66 patients with three different reconstruction methods: standard high sensitivity reconstruction, European Association of Nuclear Medicine (EANM) Research Ltd. (EARL) reference standards 1 (EARL1) and 2 (EARL2). Histopathology (27 patients, 41%) or follow-up PET/CT 9 months after end of treatment (39 patients, 59%) served as reference standard. HCS 4 and 5 were rated as positive, 1-3 negative. The performance of HCS for all methods and intermethod concordance was assessed. RESULTS:A total of 17 (26%) patients had tumor persistence. There was no significant difference in the performance of the reconstruction methods regarding tumor persistence. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for PET/CT with HCS for overall tumor persistence was 77, 80, 57, 91, and 79% for sensitivity reconstruction, 65, 90, 69, 88, and 83% for EARL1 and 71, 82, 57, 89, and 79% for EARL2. The intermethod concordance of HCS across all sites demonstrated a substantial to perfect agreement with Cohens κ ranging from 0.6 to 1.0. CONCLUSION:PET/CT HCS for therapy response assessment in head and neck cancer serves as a robust Score independent of newer sensitive reconstructions. Despite the high NPV of PET/CT in this situation the unsatisfactory PPV remains challenging.

PURPOSE:To evaluate the usefulness of [18F] fluoro- d -glucose PET combined with computed tomography ([ 18 F]FDG PET/CT) in staging T1 lung tumors with pure solid morphology on CT, focusing on the different histology subtypes, accuracy, detection rate of metastases, and its impact on changes in TNM staging. PATIENTS AND METHODS:Retrospectively, 238 patients with lung cancer and T1 nodules with pure solid morphology on CT scan, staged with [ 18 F]FDG PET/CT and chest contrast-enhanced CT (ceCT) were included. Primary tumor (T) sizes were assessed on chest ceCT and PET/CT. Maximum standardized uptake values (SUVmax) of the primary lung tumor were obtained from PET. Prevalence of lymph node and distant metastases was assessed for the three substages of T1 lung cancer (T1a, T1b, and T1c). RESULTS:Sixty-two (26%) patients with solid T1 lung cancer had lymph node metastases (T1a: 22%, T1b: 16%, T1c: 38%), and 29 (12%) showed distant metastases (T1a: 11%, T1b: 11%, T1c: 14%) in PET/CT imaging. [ 18 F]FDG PET/CT detected distant metastases in 12 patients with negative chest ceCT. [ 18 F]FDG PET/CT upstaged 26 patients (11%) and downstaged 13 patients (6%) compared with ceCT. Primary tumor histological subtypes and SUVmax values significantly correlated with the risk of lymph node and distant metastases ( P  < 0.001). However, the sensitivity for mediastinal nodal detection (N+) was poor with both CT (35%) and [ 18 F]FDG PET/CT (47.5%). CONCLUSION:[ 18 F]FDG PET/CT is useful for staging of pure solid T1 lung cancer with a detection rate of 26% for lymph node metastases and 12% for distant metastases. [ 18 F]FDG PET/CT is more accurate and has a higher positive predictive value than chest ceCT and leads to a change in the TNM stage in 17% of patients. Due to the limited sensitivity of FDG PET/CT in detecting lymph node metastases, lymphadenectomy cannot be omitted even in small pure solid T1 lung cancer.

PURPOSE:To compare the performance of pseudoplanar (PP) images reprojected from bone single photon emission computed tomography/computed tomography (SPECT/CT) against 'real' planar bone scintigraphy for the assessment of localization and grading of radiotracer uptake of active osteoarthritic joints in the foot and ankle. Noninferiority of PP images would shorten the protocol substantially. METHODS:Late-phase real planar (RP) and SPECT/CT reconstructed PP images of 96 feet in 48 patients (22 women, 26 men, median age: 49 years, interquartile range: 34-67 years) with foot and ankle osteoarthritis were independently evaluated by three different readers. Presence, localization, and uptake grade (grade 1: mild, 2: moderate, and 3: high uptake of the radiotracer) of the active osteoarthritic joints were assessed. SPECT/CT served as a reference standard, and maximum standardized uptake value (SUV max ) was measured for all active foot and ankle joints. RESULTS:Overall, 123 of 3168 joints in 48 patients had active osteoarthritis (OA) on SPECT/CT. The most frequently affected joints were the tarsometatarsal ( n  = 29), upper ankle (27), lower ankle (23), and talonavicular (15) joints. The mean SUV max of all active joints was 11.9 ± 7.5. The rate of correct detection and localization of active joints for the three readers was 77/82/85% for RP and 80/81/81% for PP, without significant difference. There was substantial agreement between RP and PP images among all the readers (R1 : 0.70, R2 : 0.76, R3 : 0.74). There was a significant correlation for visual uptake grading among all the readers for RP and PP images ( P  = 0.001). CONCLUSION:Planar images can be replaced by reconstructed PP images, leading to a substantially time-saving foot and ankle bone SPECT/CT protocol, as PP images are noninferior to planar images for the detection, localization, and grading of osteoarthritis. We expect that further technical advances coupled with artificial intelligence will improve the performance of hybrid imaging in nononcologic indications.

PURPOSE:This study aimed to evaluate correlation between various parameters from integrated 82-rubidium PET/coronary computed tomography angiography (RbPET/CCTA), like coronary artery calcium (CAC) score, coronary artery disease-reporting and data system (CAD-RADS), myocardial ischemia scores, and myocardial blood flow parameters [stress myocardial blood flow (sMBF) and myocardial flow reserve (MFR)]. METHODS:In this retrospective study, 184 consecutive patients [107 women, 77 men, median age: 67 years [(interquartile range: 61-74 years)] with suspicion of CAD were imaged with RbPET/CCTA in the 'one-stop imaging' approach. The association between CAC score, CAD-RADS, relative perfusion, and myocardial blood flow was assessed. RESULTS:There was a weak but statistically significant inverse correlation between the global CAD-RADS score and global sMBF ( ρ = -0.239, P = 0.001) and global MFR ( ρ = -0.248, P = 0.0001). There was a significant difference in CAD-RADS 3-5 vs. CAD-RADS 0-2 for global as well as per-vessel sMBF and MFR values ( P < 0.05). There was a very weak inverse correlation between global CAC and global sMBF ( ρ = -0.165, P = 0.026) and a nonsignificant, very weak inverse correlation between global CAC and global MFR ( ρ = -0.120, P = 0.106). CONCLUSION:Combined CCTA and RbPET 'one-stop imaging' provides comprehensive anatomical and physiological information in patients with suspected CAD. The PET and computed totmography parameters seem to lack linear and robust correlation. In the given circumstances, CAD-RADS scores appear to have a relatively better, though weak, correlation with sMBF, MFR, and relative ischemia scores compared with CAC scores.

Besides tumor imaging, 18fluorine-fluorodeoxyglucose (FDG) is equally useful for the detection of inflammatory diseases such as polymyalgia rheumatica and large vessel vasculitis. Critical incidental findings might be observed with FDG positron emission tomography/computed tomography (PET/CT) needing urgent medical attention and intervention. We present a case of an 81-year-old patient with a history of polymyalgia rheumatica. Cardiac activity representing an evolving non-ST segment elevation myocardial infarction was detected incidentally by FDG PET/CT.

Objective 18 F-fluorocholine PET/CT is considered the imaging gold standard for detection of hyperfunctioning parathyroid glands . However, increased uptake might also occur in the thyroid gland. The aim of our study was to assess the incidence and significance of 18 F-fluorocholine uptake in the thyroid gland in patients with hyperparathyroidism. Materials and methods This retrospective study includes 195 consecutive patients with hyperparathyroidism, who underwent 18 F-fluorocholine PET/CT, for detection of hyperfunctioning parathyroid glands. PET/CT images were reviewed by two nuclear medicine physicians for the presence of focal or diffuse thyroid uptake. PET/CT results were compared with laboratory parameters, ultrasonography, EU-TIRADS classification in the presence of thyroid nodules, cytology, and final histology. Results 25 patients (13%) showed 18 F-fluorocholine uptake in the thyroid gland: focal thyroid uptake (FTU) in 7 patients (4%), diffuse thyroid uptake (DTU) in 8 patients (4%), and combined uptake (FTU + DTU) in 10 patients (5%), with a total of 20 active thyroid nodules. There was no correlation between EU-TIRADS classification and PET parameters. One highly 18 F-fluorocholine active thyroid nodule and one isoactive thyroid nodule turned out to be papillary thyroid cancers in the final histology; 50% of the patients with DTU had Hashimoto’s thyroiditis. Conclusion Incidental 18 F-fluorocholine uptake in the thyroid gland was observed in 13% of patients. As reported for 18 F-FDG, focal 18 F-fluorocholine uptake might represent thyroid cancer and should be evaluated with ultrasound and, if indicated, with fine-needle aspiration cytology. Diffuse 18 F-fluorocholine uptake most likely represents multinodular goiter or Hashimoto’s thyroiditis.

ABSTRACT:Localized pulmonary amyloidosis forming a solitary mass known as "amyloidoma of the lung" is rare. Differentiation from lung cancer can be difficult due to suspicious features on CT and high 18 F-FDG uptake. We present a case of a 77-year-old woman with an incidental lung lesion on abdominal CT. Further evaluation with chest CT and 18 F-FDG PET/CT maintained the suspicion of lung cancer. However, histology revealed amyloidoma without signs of malignancy. Knowledge of imaging similarities between pulmonary amyloidomas and malignancies is important for interpreting 18 F-FDG PET/CT of lung tumors; however, only biopsy can confirm the rare differential diagnosis such as pulmonary amyloidoma.

Purpose The purpose of this study was to evaluate and quantify the prevalence of increased uptake in SPECT/CT in symptomatic and asymptomatic foot and ankle joints in patients with osteoarthritis. Methods In 63 patients with osteoarthritis (OA), the painful symptomatic foot (SF) and asymptomatic contralateral foot (AF) were imaged with bone SPECT/CT. Presence, localization, and maximum standardized uptake value (SUV max ) of the active joints were assessed for SF and AF. CT OA grade (grade 1: mild, grade 2: moderate, grade 3: severe) and presence of five morphological features of OA (joint space narrowing, subchondral sclerosis, subchondral cysts, irregular joint margins, and osteophytes) were evaluated. Results In total 32 (51%) patients showed additional uptake in the AF, whereas 31 (49%) patients showed it only in the SF. SF showed more active joints than AF (106 vs. 43). CT OA grades positively correlated with SUV max (Kendall’s tau b = 0.62, P < 0.001). SUV max values (per foot) in SF were higher in patients with uptake in bilateral feet (SF+, AF+) [median (IQR): 17.9 (10.7–23.3)] as compared with patients with active sites only in the SF (SF+, AF−) [10.4 (6.4–19.1); P < 0.001]. Number of active OA joints in SF was higher in patients with bilateral uptake ( P = 0.017). Conclusion In conclusion, half of the patients exhibited increased uptake in the contralateral asymptomatic foot. SUV max showed a significant correlation to CT osteoarthritis grade, in the symptomatic and asymptomatic foot. Future follow-up studies will provide further insights into the prognostic and therapeutic value of these findings.

Localized pulmonary amyloidosis forming a solitary mass known as "amyloidoma of the lung" is rare. Differentiation from lung cancer can be difficult due to suspicious features on CT and high F-18-FDG uptake. We present a case of a 77-year-old woman with an incidental lung lesion on abdominal CT. Further evaluation with chest CT and F-18-FDG PET/CT maintained the suspicion of lung cancer. However, histology revealed amyloidoma without signs of malignancy. Knowledge of imaging similarities between pulmonary amyloidomas and malignancies is important for interpreting F-18-FDG PET/CT of lung tumors; however, only biopsy can confirm the rare differential diagnosis such as pulmonary amyloidoma.

This chapter introduces the jaw conditions where bone SPECT/CT can contribute to patient management. Hemimandibular elongation/condylar hyperplasia is a common condition with an important role for SPECT/CT in diagnosis and management. In osteomyelitis and osteonecrosis of the jaws, SPECT/CT can contribute in the diagnosis, staging disease extent, guiding surgery, and assessment of treatment response. Finally, bone SPECT/CT can be used to assess degenerative changes of the temporomandibular joint and various benign and malignant tumors.

Tarsal coalition (TC) is a congenital abnormal connection (fibrous, cartilaginous, or osseous) between two or more bones in the hind and midfoot, mostly consisting of calcaneonavicular or talocalcaneal coalition, and is often asymptomatic. However, TCs may result in foot motion limitation and pain with or without flatfoot (pes planus), arising in adolescents and young adults. Appropriate imaging is needed to pinpoint foot pain in the (suspected) TC, starting with plain radiographs. Still, normal radiographs do not exclude TCs. Computed tomography (CT) and MRI are frequently used advanced imaging techniques. CT alone has known limited sensitivity in cartilaginous and fibrous TCs and correlation between CT abnormalities and pain may be challenging, as solely anatomical changes in TCs are often asymptomatic. MRI can depict soft tissue abnormalities in TC with high accuracy. Nonetheless, after the implantation of metallic osteosynthesis material, MRI is often limited due to image distortion, signal loss, and misregistration. Bone scintigraphy with [99mTc]Tc-diphosphonate single photon emission computed tomography/CT (bone-SPECT/CT) is a known sensitive tool to detect osteoblastic bone pathology. However, the literature concerning bone-SPECT/CT in TC patients is limited. This article reviews bone-SPECT/CT patterns in TCs, how it complements other imaging techniques and their relation to clinical complaints. Bone-SPECT/CT excels in accurate bone pathology characterization in TC, confidently excluding synchronous lesions elsewhere, and offering optimal insight into osseous structures and 3D-localization of bone metabolism for surgery planning. Furthermore, even with implanted osteosynthesis material, bone-SPECT/CT can pinpoint the culprit pain generator, where MRI is either contra-indicated or considerably hampered.

OBJECTIVE:To evaluate the value of SPECT/CT (single photon emission computed tomography/computed tomography) in foot and ankle arthrodesis and development of secondary osteoarthritis in the adjacent joints. MATERIALS AND METHODS:SPECT/CT of 140 joints in the foot and ankle (34 upper ankle (UA), 28 lower ankle (LA), 27 talonavicular (TN), 12 calcaneo-cuboidal (CC), and 39 other smaller joints after arthrodesis in 72 patients were evaluated retrospectively regarding fusion grade in CT (0 = no fusion, 1 = < 50% fusion, 2 = > 50% fusion, 3 = complete fusion) and radiotracer uptake (0 = no uptake, 1 = mild uptake, 2 = moderate uptake, 3 = high uptake) on SPECT/CT. Severity of osteoarthritis (1 = mild, 2 = moderate, 3 = severe) and radiotracer uptake grade in adjacent joints was also assessed. In 54 patients, clinical information about interventions in the follow-up was available. RESULTS:According to the SPECT/CT, arthrodesis was successful (grade 2 or 3 CT fusion and grade 0 or 1 uptake) in 73% (25/34) of UA joints, 71% (20/28) of LA joints, 67% (18/27) TN, 100% (12/12) CC joints, and 62% (24/39) of other smaller joints. In 12 joints, there were discrepant findings in SPECT/CT (fusion grade 2 and uptake grade 2 or 3 (n = 9); or, fusion grade 0 or 1 and uptake grade 1 (n = 3)). The fusion rate 6-12 months after arthrodesis was 42% (14/33), 59% (20/34) after 13-24 months, and 89% (65/73) after more than 24 months, respectively. Average radiotracer uptake in arthrodesis decreased with age: 6-12 months: 1.60, 12-24 months: 1.32, > 24 months: 0.38. There was a significant negative correlation between radiotracer uptake grade and CT fusion grade. Osteoarthritis was observed in 131 adjacent joints. During the post scan follow-up, additional arthrodeses were performed in 33 joints, of which 11 joints were re-arthrodesis and 22 were new arthrodeses in osteoarthritic adjacent joints. All these 11 joints with failed arthrodesis had grade 0 of CT fusion and grade 2 or 3 of radiotracer uptake. All 22 adjacent joints with osteoarthritis, which subsequently underwent arthrodesis, had grade 2 or 3 radiotracer uptake, and the primary arthrodesis joints were healed and fused in all these cases. CONCLUSION:Bone SPECT/CT is a valuable hybrid imaging tool in the evaluation of foot and ankle arthrodesis and gives additional useful information about the development of secondary osteoarthritis in the adjacent joints with higher value for the assessment of secondary osteoarthritis. A practical four-type classification ('Lucerne Criteria') combining metabolic and morphologic SPECT/CT information for evaluation of arthrodesis joints has been proposed.