Preoperative CA19‑9 level and dual time point FDG‑PET/CT as strong biological indicators of borderline resectability in pancreatic cancer: A retrospective study

Tumor resectability, which is increasingly determined based on preoperative chemotherapy, is critical in determining the best treatment for pancreatic cancers. The present study evaluated the usefulness of serum carbohydrate antigen 19-9 (CA19-9) and the preoperative 8F-fluorodeoxyglucose positron emission tomography/computed tomography standardized uptake value (SUV) percentage change (SUVmax%=[(SUVmax2-SUVmax1)/SUVmax1] ×100, where SUVmax1 and SUVmax2 represent the initial and delayed phases, respectively) as biological factors indicative of tumor resectability. The present study included patients with resectable pancreatic cancer who underwent complete surgical resection, for whom both CA19-9 and SUVmax% were documented using cut-off values of 500 U/ml and 24.25%, respectively. Patients were classified as follows: i) High CA19-9 and SUVmax%: both CA19-9 and SUVmax% were elevated; ii) high CA19-9 or SUVmax%: either CA19-9 or SUVmax% were elevated; or iii) low CA19-9 and SUVmax%: neither value met the cut-off. Relapse-free survival (RFS) and overall survival (OS) were calculated, for which univariate and multivariate analyses were performed. Of the 86 patients included, 39 were classified as high CA19-9 or SUVmax% and 12 as high CA19-9 and SUVmax%, with the former group having a significantly worse RFS (vs. low CA19-9 and SUVmax%; P<0.001; vs. high CA19-9 or SUVmax%; P=0.011) and OS (vs. low CA19-9 and SUVmax%, P=0.002; vs. high CA19-9 or SUVmax%, P<0.001). Therefore, high CA19-9 and SUVmax% was an independent predictor of worse RFS (P<0.001) and OS (P=0.003). In conclusion, CA19-9 and SUVmax% can be utilized as biological indicators of resectability.

Prostate Cancer Radioligand Therapy: Beta-labeled Radiopharmaceuticals

Prostate cancer is the most common malignancy in men worldwide, with an estimated 174,650 new cases per year in the United States, and the second cancer-related cause of death, after lung cancer, with 31,620 deaths per year. While the 5 year survival rate for prostate cancer in patients without metastatic spread is nearly 100%, those with distant metastases have 5 year survival rates of approximately 30%. Initial diagnosis and assessment are based on PSA levels, Gleason score (derived from prostate biopsy), and advanced imaging modalities, including prostate MR imaging and PSMA-PET/computed tomography in patients with high-risk features.

The effect of prednisolone and a short-term prednisolone discontinuation for the diagnostic accuracy of FDG-PET/CT in polymyalgia rheumatica-a prospective study of 101 patients

PURPOSE

2-[18F]Fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) has been suggested as an imaging modality to diagnose polymyalgia rheumatica (PMR). However, the applicability of FDG-PET/CT remains unclear, especially following glucocorticoid administration. This study aimed to investigate the diagnostic accuracy of FDG-PET/CT before and during prednisolone treatment, as well as following short-term prednisolone discontinuation.

METHODS

Treatment naïve suspected PMR patients were clinically diagnosed at baseline and subsequently had an FDG-PET/CT performed. Patients diagnosed with PMR were administered prednisolone following the first FDG-PET/CT and had a second FDG-PET/CT performed after 8 weeks of treatment. Subsequently, prednisolone was tapered with short-term discontinuation at week 9 followed by a third FDG-PET/CT at week 10. An FDG-PET/CT classification of PMR/non-PMR was applied, utilizing both the validated Leuven score and a dichotomous PMR score. The final diagnosis was based on clinical follow-up after 1 year.

RESULTS

A total of 68 and 27 patients received a final clinical diagnosis of PMR or non-PMR. A baseline FDG-PET/CT classified the patients as having PMR with a sensitivity/specificity of 86%/63% (Leuven score) and 82%/70% (dichotomous score). Comparing the subgroup of non-PMR with inflammatory diseases to the PMR group demonstrated a specificity of 39%/54% (Leuven/dichotomous score). After 8 weeks of prednisolone treatment, the sensitivity of FDG-PET/CT decreased to 36%/41% (Leuven/dichotomous score), while a short-term prednisolone discontinuation increased the sensitivity to 66%/60%.

CONCLUSION

FDG-PET/CT has limited diagnostic accuracy for differentiating PMR from other inflammatory diseases. If FDG-PET/CT is intended for diagnostic purposes, prednisolone should be discontinued to enhance diagnostic accuracy.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT04519580). Registered 17th of August 2020.

FDG-PET/CT for investigation of pyrexia of unknown origin: a cost of illness analysis

BACKGROUND

Our study aims to explore the current utilisation of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the diagnostic pathway of pyrexia of unknown origin (PUO) and associated cost of illness in a large tertiary teaching hospital in Australia.

METHOD

1257 febrile patients between June 2016 and September 2022 were retrospectively reviewed. There were 57 patients who met the inclusion criteria of "classical PUO", of which FDG-PET/CT was performed in 31 inpatients, 15 outpatients and 11 inpatients did not have an FDG-PET/CT scan. The patient demographics, clinical characteristics and inpatient cost were analysed, together with the diagnostic performance of FDG-PET/CT and impact on clinical management.

RESULT

The mean age, length of stay and total cost of admission were higher for inpatients who received FDG-PET/CT versus those who did not. The median cost per patient-bed-day did not differ between the two groups. Inpatients who received earlier FDG-PET/CTs (≤ 7 days from admission) had shorter length of stays and lower total cost compared to those who received a later scan. A negative FDG-PET/CT scan, demonstrating no serious or life-threatening abnormalities resulted in subsequent discharge from hospital or outpatient clinic in 7/10 (70%) patients. There were 11/40 (28%) scans where ancillary abnormalities were identified, requiring further evaluation.

CONCLUSION

FDG-PET/CT showed high diagnostic accuracy and significant impact on patient management in patients with PUO. FDG-PET/CT performed earlier in admission for PUO was associated with shorter length of stay and lower total cost.

Miliary tuberculosis diagnosed by diffuse hepatic uptake on PET/CT and transjugular liver biopsy

The patient was an 81-year-old man. In his 20s, he had been treated with pharmacotherapy for pulmonary tuberculosis for 1 year. He presented to the Department of Respiratory Medicine with a chief complaint of dyspnea. The possibility of respiratory disease appeared to be low, but hepatic impairment was detected. The patient was thus referred to our department. Though the cause of hepatic impairment was unknown, the soluble interleukin-2 receptor level was elevated, suggesting malignant lymphoma. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) revealed diffuse, homogenous, intense FDG uptake in the entire liver, and transjugular liver biopsy confirmed the diagnosis. Histopathological examination revealed an epithelioid granuloma, and auramine staining was positive for bacilli suggestive of tuberculosis. CT revealed diffuse micronodular shadows in the lung, yielding a diagnosis of miliary tuberculosis. Therefore, the patient was prescribed antituberculosis medication by the Department of Respiratory Medicine. His subsequent clinical course was good. The miliary (hepatic) tuberculosis was typical based on the diffuse, homogenous, intense FDG uptake throughout the liver observed on PET-CT.

18 F-Fluorodeoxyglucose Uptake in Bilateral Diaphragmatic Crura: A Relatively Uncommon Benign Variant Noted in a Treated Case of Extraosseous Paraspinal Ewing's Sarcoma

A toddler was diagnosed with extraosseous Ewing's sarcoma, primary large epidural paraspinal soft tissue in the lumbar region encasing the cord and neural foramen from D12-L1 to L4-L5. After eight cycles of induction chemotherapy with vincristine, doxorubicin, and cyclophosphamide alternating with etoposide and ifosfamide, 18 F-FDG positron emission tomography/computed tomography ( 18 F-FDG-PET/CT) scan confirmed no active disease. Later external beam radiotherapy (EBRT) at D10-L5 was completed. At 3 months follow-up, 18 F-FDG-PET/CT reconfirmed no residual/active disease; however, a new incidental finding of diffuse benign bilateral diaphragmatic 18 F-FDG uptake was noted in the clinically asymptomatic patient, which remained unexplained.

Prospective Assessment of Fluorine-18-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography (FDG-PET/CT) for Early Identification of Checkpoint-Inhibitor-Induced Pseudoprogression

The activity of immune checkpoint inhibitors (ICIs) in patients with metastatic melanoma is often monitored using fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scans. However, distinguishing disease progression (PD) from pseudoprogression (PsPD), where increased FDG uptake might reflect immune cell activity rather than tumor growth, remains a challenge. This prospective study compared the efficacy of dual-time point (DTP) FDG-PET/CT with modified response criteria (PERCIMT) in differentiating PsPD from PD. From July 2017-January 2021, 41 patients suspected to have PsPD on an evaluation scan were prospectively included (29 evaluable). A subsequent DTP FDG-PET/CT scan was conducted within 14 days, followed by a confirmatory FDG-PET/CT scan. Additionally, PERCIMT were applied. DTP FDG-PET/CT identified 24% with PsPD and 76% with PD. Applying PERCIMT criteria, 69% showed PsPD, while 31% had PD. On follow-up, 10 patients (34%) demonstrated confirmed PsPD, while 19 (66%) exhibited PD. The sensitivity and specificity of DTP FDG-PET/CT were 20% and 74%, respectively, and for PERCIMT this was 80% and 37%, respectively. Our findings suggest limited efficacy of DTP FDG-PET/CT in distinguishing PsPD from PD in ICI-treated patients with metastatic melanoma. The use of PERCIMT could complement clinical assessment and be incorporated in multidisciplinary team conferences for enhanced decision-making.

Role of 18F-fluorodeoxyglucose positron-emission tomography/computed tomography in restaging of adrenocortical carcinoma

Background

The objective was to retrospectively evaluate the contribution of fluorodeoxyglucose [18F] positron emission tomography/computed tomography (18FDG-PET/CT) to the re-staging of adrenocortical carcinoma (ACC).

Materials and methods

A total of 16 patients (10 males and 6 females), who underwent adrenalectomy due to adrenocortical carcinoma and 18FDG-PET/CT scan to re-stage the tumor between July 2007 and April 2013, were included in the present study. The mean age was 53.37 ± 13.91 years (min: 30, max: 74) The patients were required to fast for six hours prior to scanning, and whole-body PET scanning from the skull base to the upper thighs was performed approximately 1 h after the intravenous injection of 555 MBq of F-18 FDG. Whole body CT scanning was performed in the cranio-caudal direction. FDG-PET images were reconstructed using CT data for attenuation correction. Suspicious recurrent or metastatic lesions were confirmed by histopathology or clinical follow-up.

Results

Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 18FDG-PET/CT were 100%, 83.3%, 90.9%, 83.3%, and 93.7%, respectively.

Conclusion

18FDG-PET/CT detects local recurrence and/or distant metastases with high accuracy in the re-staging of operated adrenocortical carcinoma. It is considered that the procedure could play an important role in treatment decision after the operation and post-operative follow-up and could influence the entire decision-making process.

Integrated FDG-PET/CT contribution over cross-sectional imaging in recurrence or progression of pancreaticobiliary neoplasms

PURPOSE

We aim to compare FDG-PET/CT and cross-sectional imaging (contrastenhanced CT/MRI) diagnostic abilities in detecting recurrence/progression of pancreaticobiliary system tumors and to reveal the clinical impact of integrated FDGPET/CT to CT/MRI on patient management.

MATERIALS AND METHODS

FDG-PET/CT and CT/MRI scans of 70 patients from initiation of treatment until proven recurrence/progression were retrospectively evaluated. FDGPET/CT and contrast-enhanced CT/MRI accuracy, sensitivity, specificity, PPV and NPV are compared in terms of overall recurrence/progression diagnosis and sitespecific concern; local disease, local lymph node, and distant organ metastasis. The impact of integrated FDG-PET/CT on patient management is scrutinized.

RESULTS

CT/MRI has higher sensitivity than FDG-PET/CT in detecting loco-regional involvement (90% vs 76.7% P: 0.152), local lymph node metastasis (88.9% vs 77.8%, P: 0.380) and distant organ metastasis (96.5% vs 80.7%; P: 0.006) in tumor recurrence/progression. In overall diagnosis, CT/MRI is more sensitive and accurate but less specific than FDG-PET/CT (92.3% vs 87.7%; 87.1% vs 84.2%; 40% vs 20%, respectively). In 8% (6/70) of patients FDG-PET/CT had a major impact on patient management.

CONCLUSION

FDG-PET/CT and cross-sectional imaging have different advantages and shortcomings. In recurrence/progression, recognition of early changes is more feasible by CT/MRI. However, inconsistency of morphologic and metabolic findings is important reason of cross-sectional imaging failure. FDG-PET/CT is superior in showing extraabdominal metastases, but missing small-volume lesions and misinterpreting inflammatory changes are still a problem lowering its sensitivity. Nevertheless FDGPET/CT is good option for guiding undetermined imaging findings or clinic-radiologic mismatch.

Increased Thyroidal Activity on Routine FDG-PET/CT after Combination Immune Checkpoint Inhibition: Temporal Associations with Clinical and Biochemical Thyroiditis

BACKGROUND

FDG-PET/CT used for immune checkpoint inhibitor (ICI) response assessment can incidentally identify immune-related adverse events (irAEs), including thyroiditis. This study aimed to correlate the time course of FDG-PET/CT evidence of thyroiditis with clinical and biochemical evolution of thyroid dysfunction.

METHODS

A retrospective review was performed by two independent blinded nuclear medicine physicians (NMPs) of thyroidal FDG uptake in 127 patients who underwent PET/CT between January 2016 and January 2019 at baseline and during treatment monitoring of combination ICI therapy for advanced melanoma. Interobserver agreement was assessed and FDG-PET/CT performance defined by a receiver-operating characteristic (ROC) curve using thyroid function tests (TFTs) as the standard of truth. Thyroid maximum standardized uptake value (SUVmax) and its temporal changes with respect to the longitudinal biochemistry were serially recorded.

RESULTS

At a median of 3 weeks after commencing ICI, 43/127 (34%) had a diagnosis of thyroiditis established by abnormal TFTs. FDG-PET/CT was performed at baseline and at a median of 11 weeks (range 3-32) following the start of therapy. ROC analysis showed an area under the curve of 0.87 (95% CI 0.80, 0.94) for FDG-PET/CT for detection of thyroiditis with a positive predictive value of 93%. Among patients with biochemical evidence of thyroiditis, those with a positive FDG-PET/CT were more likely to develop overt hypothyroidism (77% versus 35%, p < 0.01). In the evaluation of the index test, there was an almost perfect interobserver agreement between NMPs of 93.7% (95% CI 89.4-98.0), kappa 0.83.

CONCLUSION

Increased metabolic activity of the thyroid on routine FDG-PET/CT performed for tumoral response of patients undergoing ICI therapy is generally detected well after routine biochemical diagnosis. Elevation of FDG uptake in the thyroid is predictive of overt clinical hypothyroidism and suggests that an ongoing robust inflammatory response beyond the initial thyrotoxic phase may be indicative of thyroid destruction.

Differentiating Hodgkin Lymphoma and Sarcoid Reaction in Subsequent FDG-PET/CT: A Case Report and Literature Review

Sarcoidosis is frequently associated with various hematological and solid tumors; it can be discovered by chance during tumor evaluations. Sarcoidosis can occur before some cancers, coexist with others, or be diagnosed 1 to 2 years later. Sarcoid reaction affecting hilar and mediastinal lymph nodes can pose a diagnostic challenge in patients with histopathological confirmation of Hodgkin lymphoma who are being evaluated using fluorodeoxyglucose-positron emission tomography computed tomography (FDG-PET/CT) scan because it cannot be easily distinguished from lymphoma infiltration. The presence of an increase or persistence of a prominent activity on a follow-up FDG-PET/CT scan after chemotherapy treatment for lymphoma that is associated with a complete metabolic response in the site of the primarily diagnosed lymphomatous disease is highly suggestive of concurrent sarcoidosis and necessitates careful assessment to avoid unnecessary therapy.

An Innovative Non-Linear Prediction Model for Clinical Benefit in Women with Newly Diagnosed Breast Cancer Using Baseline FDG-PET/CT and Clinical Data

Objectives: We aimed to develop a novel non-linear statistical model integrating primary tumor features on baseline [18F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), molecular subtype, and clinical data for treatment benefit prediction in women with newly diagnosed breast cancer using innovative statistical techniques, as opposed to conventional methodological approaches. Methods: In this single-center retrospective study, we conducted a comprehensive assessment of women newly diagnosed with breast cancer who had undergone a FDG-PET/CT scan for staging prior to treatment. Primary tumor (PT) volume, maximum and mean standardized uptake value (SUVmax and SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured on PET/CT. Clinical data including clinical staging (TNM) but also PT anatomical site, histology, receptor status, proliferation index, and molecular subtype were obtained from the medical records. Overall survival (OS), progression-free survival (PFS), and clinical benefit (CB) were assessed as endpoints. A logistic generalized additive model was chosen as the statistical approach to assess the impact of all listed variables on CB. Results: 70 women with newly diagnosed breast cancer (mean age 63.3 ± 15.4 years) were included. The most common location of breast cancer was the upper outer quadrant (40.0%) in the left breast (52.9%). An invasive ductal adenocarcinoma (88.6%) with a high tumor proliferation index (mean ki-67 expression 35.1 ± 24.5%) and molecular subtype B (51.4%) was by far the most detected breast tumor. Most PTs displayed on hybrid imaging a greater volume (12.8 ± 30.4 cm3) with hypermetabolism (mean ± SD of PT maximum SUVmax, SUVmean, MTV, and TLG, respectively: 8.1 ± 7.2, 4.9 ± 4.4, 12.7 ± 30.4, and 47.4 ± 80.2). Higher PT volume (p < 0.01), SUVmax (p = 0.04), SUVmean (p = 0.03), and MTV (<0.01) significantly compromised CB. A considerable majority of patients survived throughout this period (92.8%), while five women died (7.2%). In fact, the OS was 31.7 ± 14.2 months and PFS was 30.2 ± 14.1 months. A multivariate prediction model for CB with excellent accuracy could be developed using age, body mass index (BMI), T, M, PT TLG, and PT volume as predictive parameters. PT volume and PT TLG demonstrated a significant influence on CB in lower ranges; however, beyond a specific cutoff value (respectively, 29.52 cm3 for PT volume and 161.95 cm3 for PT TLG), their impact on CB only reached negligible levels. Ultimately, the absence of distant metastasis M displayed a strong positive impact on CB far ahead of the tumor size T (standardized average estimate 0.88 vs. 0.4). Conclusions: Our results emphasized the pivotal role played by FDG-PET/CT prior to treatment in forecasting treatment outcomes in women newly diagnosed with breast cancer. Nevertheless, careful consideration is required when selecting the methodological approach, as our innovative statistical techniques unveiled non-linear influences of predictive biomarkers on treatment benefit, highlighting also the importance of early breast cancer diagnosis.

Integration of PET in DLBCL

F-fluorodeoxyglucose positron emission tomography-computerized tomography (18FDG-PET/CT) is the gold-standard imaging modality for staging and response assessment for most lymphomas. This review focuses on the utility of 18FDG-PET/CT, and its role in staging, prognostication and response assessment in diffuse large B-cell lymphoma (DLBCL), including emerging possibilities for future use.

FDG-PET/CT discriminates between patients with and without lymphomas in primary Sjögren's syndrome

OBJECTIVES

To assess the usefulness of [18F]-fluorodeoxyglucose (FDG)-PET/CT (i) to discriminate between primary SS (pSS) patients with and without lymphomas and (ii) to evaluate systemic disease activity in pSS.

METHODS

ACR-EULAR-positive pSS patients who underwent FDG-PET/CT were included. Scans were visually evaluated and quantitative analysis was performed by measuring standardized uptake values (SUV) of salivary and lacrimal glands and systemic regions. Receiver operating characteristic curve analyses were performed to find SUV cut-off values to discriminate between lymphoma and non-lymphoma.

RESULTS

Of the 70 included patients, 26 were diagnosed with a pSS-associated lymphoma, mostly of the mucosa-associated lymphoid tissue type (23/26). Lymphoma patients showed higher FDG uptake in the parotid and submandibular glands, and more frequently showed presence of nodular lung lesions, compared with non-lymphoma patients. The accuracy of the maximum SUV (SUVmax) in the parotid and submandibular gland to predict lymphoma diagnosis was good, with optimal cut-off points of 3.1 and 2.9. After combining these three visual and quantitative findings (nodular lung lesions, parotid SUVmax > 3.1 and submandibular SUVmax > 2.9), sensitivity was 92% when at least one of the three features were present, and specificity was 91% in case at least two features were present. Furthermore, FDG-PET/CT was able to detect systemic manifestations in pSS patients, mostly involving lymph nodes, entheses and lungs.

CONCLUSIONS

FDG-PET/CT can assist in excluding pSS-associated lymphomas in patients without PET abnormalities, possibly leading to a decrease of invasive biopsies in suspected lymphoma patients. Furthermore, FDG-PET/CT is able to detect systemic manifestations in pSS and can guide to the best biopsy location.

Staging fluorodeoxyglucose positron emission tomography/computed tomography for muscle-invasive bladder cancer: a nationwide population-based study

OBJECTIVE

To provide insight into the use and staging information on lymph-node involvement added by fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in patients with muscle-invasive bladder cancer (MIBC), based on a nationwide population-based cohort study.

PATIENTS AND METHODS

We analysed a nationwide cohort of patients with MIBC without signs of distant metastases, newly diagnosed in the Netherlands between November 2017 and October 2019. From this cohort, we selected patients who underwent pre-treatment staging with CT only or CT and FDG-PET/CT. The distribution of patients, disease characteristics, imaging findings, nodal status (clinical nodal stage cN0 vs cN+) and treatment were described for each imaging modality group (CT only vs CT and FDG-PET/CT).

RESULTS

We identified 2731 patients with MIBC: 1888 (69.1%) underwent CT only; 606 (22.2%) underwent CT and FDG-PET/CT, 237 (8.6%) underwent no CT. Of the patients who underwent CT only, 200/1888 (10.6%) were staged as cN+, vs 217/606 (35.8%) who underwent CT and FDG-PET/CT. Stratified analysis showed that this difference was found in patients with clinical tumour stage (cT)2 as well as cT3/4 MIBC. Of patients who underwent both imaging modalities and were staged with CT as cN0, 109/498 (21.9%) were upstaged to cN+ based on FDG-PET/CT. Radical cystectomy (RC) was the most common treatment within both imaging groups. Preoperative chemotherapy was more frequently applied in cN+ disease and in FDG-PET/CT-staged patients. Concordance of pathological N stage after upfront RC was higher among patients staged as cN+ with CT and FDG-PET/CT (50.0% pN+) than those staged as cN+ with only CT (39.3%).

CONCLUSION

Patients with MIBC who underwent pre-treatment staging with FDG-PET/CT were more often staged as lymph node positive, regardless of cT stage. In patients with MIBC who underwent CT and FDG-PET/CT, FDG-PET/CT led to clinical nodal upstaging in approximately one-fifth. Additional imaging findings may influence subsequent treatment strategies.

Advanced multiparametric MRI and FDG-PET/CT in multinodular and vacuolating neuronal tumor: A pathologically confirmed case

Multinodular and vacuolating neuronal tumor (MVNT) is a relatively new disease concept proposed in 2013 and was classified as a separate tumor type in 2021 by the World Health Organization (WHO) classification. MVNT can cause seizures but is a benign disease, with no cases of enlargement or postoperative recurrence reported. Recent reports described advanced MRI features in MVNT cases, but the diagnosis of MVNT is usually based on characteristic MRI findings of clusters of nodules. Here, we report advanced multiparametric MRI and FDG-PET/CT findings in a case of MVNT with epileptiform symptoms that was pathologically confirmed by surgery.

The Role of FDG-PET in the Evaluation of Hidradenitis Suppurativa: A Systematic Review

Hidradenitis suppurativa (HS) is a chronic skin disorder characterized by nodules, comedones, and sinus tracts that often leave prominent scarring. In recent years, non-invasive imaging techniques have been used to assess the inflammatory activity, vascularization, and treatment response of lesions. Specifically, fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans may aid in identifying systemic inflammation in patients with HS, improving diagnosis. Inflamed hypermetabolic tissues exhibit a greater uptake of FDG due to increased glucose uptake and vascularity. A systematic review was conducted to summarize the utility of nuclear imaging techniques in the diagnosis and treatment follow-up of HS. PubMed, Scopus, and ScienceDirect databases were utilized for relevant articles discussing the utility of PET scans in managing HS. A total of 51 citations were identified in the initial search. Following the review of titles, abstracts, and duplicates, 43 articles were excluded, leaving a total of eight articles for analysis. Data were extracted from each article, encompassing the number of patients, imaging techniques employed, and final results. An analysis of the data demonstrated that FDG-PET showed evidence of identifying subclinical lesions of the disease, improving the visualization of HS, and providing an objective method of assessing severity.

Circulating Tumor DNA in Head and Neck Squamous Cell Carcinoma: Association with Metabolic Tumor Burden Determined with FDG-PET/CT

BACKGROUND

The detection of circulating tumor DNA (ctDNA) with next-generation sequencing (NGS) in venous blood is a promising tool for the genomic profiling of head and neck squamous cell carcinoma (HNSCC). The association between ctDNA findings and metabolic tumor burden detected with FDG-PET/CT imaging is of particular interest for developing prognostic and predictive algorithms in HNSCC.

METHODS

Twenty-six prospectively enrolled HNSCC patients were eligible for further analysis. All patients underwent tumor tissue and venous liquid biopsy sampling and FDG-PET/CT before definitive oncologic treatment. An NGS-based commercial panel was used for a genomic analysis of the samples.

RESULTS

Maximum variant allele frequency (VAF) in blood correlated positively with whole-body (WB) metabolic tumor volume (MTV) and total lesion glycolysis (TLG) (r = 0.510, p = 0.008 and r = 0.584, p = 0.002, respectively). A positive liquid biopsy was associated with high WB-TLG using VAF ≥ 1.00% or ≥5.00% as a cut-off value (p = 0.006 or p = 0.003, respectively). Additionally, ctDNA detection was associated with WB-TLG when only concordant variants detected in both ctDNA and tissue samples were considered.

CONCLUSIONS

A high metabolic tumor burden based on FDG imaging is associated with a positive liquid biopsy and high maximum VAF. Our findings suggest a complementary role of metabolic and genomic signatures in the pre-treatment evaluation of HNSCC.

Mismatch of systematic and local inflammatory activity in Takayasu arteritis with coronary involvement: a case report

BACKGROUND

Accurate evaluation of the activity stage in Takayasu arteritis (TA) is important for the revascularization of TA with coronary artery involvement (TA-CAD). Here, we report the case of a patient with a mismatch of systemic and local inflammatory activity, leading to 13 times the need for recurrent coronary revascularization.

CASE SUMMARY

A 31-year-old woman with a family history of coronary artery disease underwent percutaneous coronary intervention (PCI) for critical ostial lesions. This patient was identified with Numano Type V TA and she underwent optimal medical therapy and PCIs. Her clinical inflammatory markers were quickly normalized. However, in-stent restenosis events recurred every 3 months. Virtual-histology intravascular ultrasound (VH-IVUS) and 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) confirmed local vascular inflammation. A coronary artery bypass graft (CABG) was also conducted. Before this procedure, both the CABG grafts and the anastomotic areas were accurately assessed with 18FDG-PET/CT. Eventually, this patient remained both angina- and event-free for 2 years post-CABG.

DISCUSSION

The persistence of TA activity despite normal clinical inflammatory markers is uncommon as is the need for recurrent revascularization after appropriate PCI management. Intracoronary imaging and 18FDG-PET/CT play a critical role in assessing TA activity as well as precisely guiding CABG grafts and anastomosis sites to prevent graft failure.

FDG-PET/CT for lymph node staging prior to radical cystectomy

BACKGROUND

¹⁸F-Fluorodeoxyglucose positron emission combined with computed tomography (FDG-PET/CT) has been proposed to improve preoperative staging in patients with bladder cancer subjected to radical cystectomy (RC).

OBJECTIVE

Our aim was to assess the accuracy of FDG-PET/CT for lymph node staging ascertained at the multidisciplinary tumour board compared to lymph node status in the surgical lymphadenectomy specimen obtained at RC, and to explore potential factors associated with false-positive FDG-PET/CT results.

DESIGN, SETTING AND PARTICIPANTS

Consecutive patients with bladder cancer undergoing RC with extended lymph node dissection between 2011 and 2019 without preoperative chemotherapy in a tertial referral cystectomy unit were included in the study.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Sensitivity, specificity, positive and negative predictive values and likelihood ratios were calculated. Potential factors investigated for association with false-positive FDG-PET/CT were; bacteriuria within four weeks prior to FDG-PET/CT, Bacillus Calmette-Guerin (BCG) treatment within 12 months prior to FDG-PET/CT and transurethral resection of bladder tumour (TURB) within four weeks prior to FDG-PET/CT.

RESULTS

Among 157 patients included for analysis, 44 (28%) were clinically node positive according to FDG-PET/CT. The sensitivity and specificity for detection of lymph node metastasis were 50% and 84%, respectively, and the corresponding positive predictive and negative predictive values were 61% and 76%. Positive and negative likelihood ratios were 3.0 and 0.6, respectively. No association was found between bacteriuria, previous BCG treatment or TURB within 28 days and false-positive FDG-PET/CT results.

CONCLUSIONS

Preoperative FDG-PET/CT prior to RC had a clinically meaningful high specificity (84%) but lower sensitivity (50%) for detection of lymph node metastases compared to lymph node status in an extended pelvic lymphadenectomy template. We could not identify any factors associated with false-positive FDG-PET/CT outcomes.

Accuracy of nodal staging by 18F-FDG-PET/CT in limited disease small-cell lung cancer

BACKGROUND

Small-cell lung cancer (SCLC) is highly aggressive with a nearly incurable disease in most cases. The most important prognostic factor is the status of the mediastinal lymph nodes. Only a small proportion of patients can be diagnosed at early stages and directed to curative multimodal treatment. Therefore, accuracy of nodal staging by (18F)-Fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) computed tomography (18F-FDG-PET/CT) in (very) limited disease SCLC, although not well investigated, is highly important.

METHODS

Treatment naive, non-bulky patients treated or diagnosed with SCLC between June 2012 and April 2020 with complete data including FDG-PET/CT and invasive mediastinal staging were retrospectively analyzed (n = 19). Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV) and accuracy of mediastinal lymph node staging of 18F-FDG-PET/CT was calculated.

RESULTS

The FDG-PET/CT showed a sensitivity of 91%, and the specificity was calculated as 87.5%. In this cohort, the disease prevalence in lymph nodes was 58% (n = 11). Positive predictive value was 91%, NPV 88% and accuracy calculated at 89%. One patient was upstaged from single-level N2 to multilevel N2. In one patient, upstaging in invasive staging was performed from N2 to N3, and one patient was downstaged from N1 to N0.

CONCLUSIONS

FDG-PET/CT is a valuable tool for the detection of distant metastases, but in mediastinal staging of SCLC some limitations might remain. Invasive methods remain the gold standard. Therefore, the mediastinal lymph nodal status of patients with SCLC screened for multimodal treatment should be further evaluated by additional invasive techniques to verify the exact N-staging and to optimize treatment stratification.

Divergent Oxidative Stress in Normal Tissues and Inflammatory Cells in Hodgkin and Non-Hodgkin Lymphoma

BACKGROUND

Previous studies reported mitochondrial and endoplasmic reticulum redox stress in peripheral blood mononucleated cells (PBMCs) of treatment-naïve Hodgkin lymphoma (HL) patients. Here, we assessed whether this response also applies to non-HL (NHL) patients, and whether the oxidative damage is a selective feature of PBMCs or, rather, also affects tissues not directly involved in the inflammatory response.

METHODS

Isolated PBMCs of 28 HL, 9 diffuse large B cell lymphoma, 8 less aggressive-NHL, and 45 controls underwent flow cytometry to evaluate redox stress and uptake of the glucose analogue 2-NBDG. This analysis was complemented with the assay of malondialdehyde (MDA) levels and enzymatic activity of glucose-6P-dehydrogenase and hexose-6P-dehydrogenase (H6PD). In all lymphoma patients, ¹⁸F-fluoro-deoxyglucose uptake was estimated in the myocardium and skeletal muscles.

RESULTS

Mitochondrial reactive oxygen species generation and MDA levels were increased only in HL patients as well as H6PD activity and 2-NBDG uptake. Similarly, myocardial FDG retention was higher in HL than in other groups as opposed to a similar tracer uptake in the skeletal muscle.

CONCLUSIONS

Redox stress of PBMCs is more pronounced in HL with respect to both NHL groups. This phenomenon is coherent with an increased activity of H6PD that also extends to the myocardium.

The effect of butylscopolamine on [18F]FDG uptake in the gastrointestinal tract is negligible and regionally variable

BACKGROUND

Butylscopolamine (or hyoscine butylbromide, trade name Buscopan^®) is occasionally administered as a premedication to reduce non-specific FDG uptake in the gastrointestinal tract based on its antiperistaltic effect. To date, there are no consistent recommendations for its use. The aim of this study was to quantify the reduction in intestinal and non-intestinal uptake by butylscopolamine administration and to derive relevance for clinical evaluation.

RESULTS

458 patients (PET/CT for lung cancer) were retrospectively reviewed. 218 patients with butylscopolamine and 240 patients without butylscopolamine had comparable characteristics. While the SUV_mean in the gullet/stomach and small intestine was significantly reduced with butylscopolamine, the colon and rectum/anus showed no difference. The liver and salivary glands showed a reduced SUV_mean, while skeletal muscle and blood pool were unaffected. An effect of butylscopolamine was particularly evident in men and patients under 65 years of age. There was no difference in the perceived confidence in the assessment of intestinal findings in the subjective evaluation, although in the butylscopolamine group further diagnostics appeared advisable more frequently.

CONCLUSIONS

Butylscopolamine reduces gastrointestinal FDG accumulation only in selected segments and, despite a significant effect, only to a small extent. A general recommendation for the use of butylscopolamine cannot be derived from these results, its use for specific issues could be considered individually.

Widespread presentation of brown tumors mimicking multiple myeloma

Brown tumors or osteitis fibrosa cystica has become a rare presentation of primary hyperparathyroidism in up-to-date clinical practice. Here, we describe a case of longstanding untreated hyperparathyroidism presenting itself with brown tumors in a 65-year-old patient. During the diagnostic work-up of this patient, bone SPECT/CT and ¹⁸F-FDG-PET/CT revealed multiple widespread osteolytic lesions. Differentiating from other bone tumors such as multiple myeloma is challenging. In this case, the final diagnosis was made by integrating the medical history, biochemical diagnosis of primary hyperparathyroidism, pathological findings and medical imaging.

Case Report: Early detection of lung carcinoid in an asymptomatic individual by blood-test initiated PET-CT imaging

We present the case of a 53-year-old woman who was diagnosed with early-stage lung cancer by targeted cancer screening consisting of an immunological biopsy-based blood test followed by radiological imaging. The PanTum Detect blood test detects the biomarkers Apo10/DNaseX and Transketolase-like 1 (TKTL1) in circulating macrophage-like cells from peripheral blood samples to identify asymptomatic individuals with a high risk for malignancy. The elevated blood test values initiated an ¹⁸F-FDG PET/CT visualization for further clarification. In this case, imaging indicated a lung carcinoma in the right upper lobe. A biopsy confirmed the presence of a lung carcinoma, which was removed surgically. Histologic examination revealed a typical I A2 carcinoid, which was completely removed, making further therapy obsolete.

Impact of minimal residual disease standardised assessment by FDG-PET/CT in transplant-eligible patients with newly diagnosed multiple myeloma enrolled in the imaging sub-study of the FORTE trial

Background

18F-FDG-PET/CT is the current standard technique to define minimal residual disease (MRD) outside the bone marrow (BM) in multiple myeloma (MM), recently standardised applying the Deauville scores (DS) to focal lesions (FS) and bone marrow uptake (BMS) and defining the complete metabolic response (CMR) as uptake below the liver background (DS <4).

Methods

In this analysis, we aimed at confirming the role of CMR, and complementarity with BM multiparameter flow cytometry (MFC) at 10^-5, in an independent cohort of newly diagnosed transplant-eligible MM patients previously enrolled in the phase II randomised FORTE trial. 109 of the 474 global patients enrolled in the trial between February 23, 2015, and April 5, 2017, who had paired PET/CT (performed at baseline [B] and preceding maintenance therapy [PM]) and MFC evaluation, were included in this analysis.

Findings

At B, 93% of patients had focal lesions within the bones (FS ≥4 in 89%) and 99% increased BM uptake (BMS ≥4 in 61%). At PM, CMR was achieved in 63% of patients, which was a strong predictor for prolonged PFS in univariate analysis at landmark time PM (HR 0.40, P = 0.0065) and in Cox multivariate analysis (HR 0.31, P = 0.0023). Regarding OS, a trend in favour of CMR was present in univariate (HR 0.44, P = 0.094), and Cox multivariate model (HR 0.17, P = 0.0037). Patients achieving both PET/CT CMR and MFC negativity at PM showed significantly extended PFS in univariate (HR 0.45, P = 0.020) and multivariate analysis (HR 0.41, P = 0.015).

Interpretation

We herein confirm the applicability and validity of DS criteria to define CMR and its prognostic relevance and complementarity with MFC at the BM level.

Funding

Amgen, Celgene/Bristol Myers Squibb, Italian Ministry of Health (RC-2022-2773423).

A machine learning tool to improve prediction of mediastinal lymph node metastases in non-small cell lung cancer using routinely obtainable [18F]FDG-PET/CT parameters

BACKGROUND

In patients with non-small cell lung cancer (NSCLC), accuracy of [18F]FDG-PET/CT for pretherapeutic lymph node (LN) staging is limited by false positive findings. Our aim was to evaluate machine learning with routinely obtainable variables to improve accuracy over standard visual image assessment.

METHODS

Monocentric retrospective analysis of pretherapeutic [18F]FDG-PET/CT in 491 consecutive patients with NSCLC using an analog PET/CT scanner (training + test cohort, n = 385) or digital scanner (validation, n = 106). Forty clinical variables, tumor characteristics, and image variables (e.g., primary tumor and LN SUVmax and size) were collected. Different combinations of machine learning methods for feature selection and classification of N0/1 vs. N2/3 disease were compared. Ten-fold nested cross-validation was used to derive the mean area under the ROC curve of the ten test folds ("test AUC") and AUC in the validation cohort. Reference standard was the final N stage from interdisciplinary consensus (histological results for N2/3 LNs in 96%).

RESULTS

N2/3 disease was present in 190 patients (39%; training + test, 37%; validation, 46%; p = 0.09). A gradient boosting classifier (GBM) with 10 features was selected as the final model based on test AUC of 0.91 (95% confidence interval, 0.87-0.94). Validation AUC was 0.94 (0.89-0.98). At a target sensitivity of approx. 90%, test/validation accuracy of the GBM was 0.78/0.87. This was significantly higher than the accuracy based on "mediastinal LN uptake > mediastinum" (0.7/0.75; each p < 0.05) or combined PET/CT criteria (PET positive and/or LN short axis diameter > 10 mm; 0.68/0.75; each p < 0.001). Harmonization of PET images between the two scanners affected SUVmax and visual assessment of the LNs but did not diminish the AUC of the GBM.

CONCLUSIONS

A machine learning model based on routinely available variables from [18F]FDG-PET/CT improved accuracy in mediastinal LN staging compared to established visual assessment criteria. A web application implementing this model was made available.

Predictive Value of Total Metabolic Tumor Burden Prior to Treatment in NSCLC Patients Treated with Immune Checkpoint Inhibition

OBJECTIVES

We aimed to assess the predictive value of the total metabolic tumor burden prior to treatment in patients with advanced non-small-cell lung cancer (NSCLC) receiving immune checkpoint inhibitors (ICIs).

METHODS

Pre-treatment 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (PET/CT) scans performed in two consecutive years for staging in adult patients with confirmed NSCLC were considered. Volume, maximum/mean standardized uptake value (SUVmax/SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were assessed per delineated malignant lesion (including primary tumor, regional lymph nodes and distant metastases) in addition to the morphology of the primary tumor and clinical data. Total metabolic tumor burden was captured by _totalMTV and _totalTLG. Overall survival (OS), progression-free survival (PFS) and clinical benefit (CB) were used as endpoints for response to treatment.

RESULTS

A total of 125 NSCLC patients were included. Osseous metastases were the most frequent distant metastases (n = 17), followed by thoracal distant metastases (pulmonal = 14 and pleural = 13). Total metabolic tumor burden prior to treatment was significantly higher in patients treated with ICIs (mean _totalMTV ± standard deviation (SD) 72.2 ± 78.7; mean _totalTLG ± SD 462.2 ± 538.9) compared to those without ICI treatment (mean _totalMTV ± SD 58.1 ± 233.8; mean _totalTLG ± SD 290.0 ± 784.2). Among the patients who received ICIs, a solid morphology of the primary tumor on imaging prior to treatment was the strongest outcome predictor for OS (Hazard ratio HR 28.04, p < 0.01), PFS (HR 30.89, p < 0.01) and CB (parameter estimation PE 3.46, p < 0.01), followed by the metabolic features of the primary tumor. Interestingly, total metabolic tumor burden prior to immunotherapy showed a negligible impact on OS (p = 0.04) and PFS (p = 0.01) after treatment given the hazard ratios of 1.00, but also on CB (p = 0.01) given the PE < 0.01. Overall, biomarkers on pre-treatment PET/CT scans showed greater predictive power in patients receiving ICIs, compared to patients without ICI treatment.

CONCLUSIONS

Morphological and metabolic properties of the primary tumors prior to treatment in advanced NSCLC patients treated with ICI showed great outcome prediction performances, as opposed to the pre-treatment total metabolic tumor burdens, captured by _totalMTV and _totalTLG, both with negligible impact on OS, PFS and CB. However, the outcome prediction performance of the total metabolic tumor burden might be influenced by the value itself (e.g., poorer prediction performance at very high or very low values of total metabolic tumor burden). Further studies including subgroup analysis with regards to different values of total metabolic tumor burden and their respective outcome prediction performances might be needed.

Dedifferentiated liposarcoma lung metastases with different FDG-PET/CT findings

BACKGROUND

Dedifferentiated liposarcoma (DDLPS) is a rare tumor and generally shows poor prognosis with the lung frequent metastatic site. 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is used for staging or metastatic evaluation of this disease. We report a case of bilateral lung metastases of DDLPS showing uncommon imaging on FDG-PET/CT with completely different FDG uptake, which made preoperative diagnosis difficult.

CASE PRESENTATION

The patient was a male in his 60 s and bilateral lung nodules were noted after proton beam therapy for retroperitoneal DDLPS. FDG-PET/CT showed high FDG uptake in the left S3 15-mm nodule but no uptake in the right S8 10-mm nodule. Thoracoscopic wedge resection for the left nodule was performed, and the pathology revealed metastasis of dedifferentiated liposarcoma. After resection of the left nodule, the right S8 nodule enlarged without FDG uptake. Thoracoscopic right S8 segmentectomy was performed, and metastasis of dedifferentiated liposarcoma was diagnosed. The 2 tumors showed completely different appearances on FDG-PET/CT with similar histopathological findings.

CONCLUSIONS

We encountered a case of multiple pulmonary metastases of DDLPS which did not follow the same imaging appearance on FDG-PET/CT. Appropriate timing of surgical resection for pathological diagnosis should be determined carefully.

Usefulness of 18F-Fluorodeoxyglucose Positron Emission Tomography in Diagnosing Polymyalgia Rheumatica and Large-Vessel Vasculitis: A Case-Control Study

INTRODUCTION

We aimed to evaluate the utility of FDG-PET/CT in diagnosing polymyalgia rheumatica (PMR) and associated large-vessel vasculitis (LVV).

METHODS

We analyzed FDG-PET/CT completed between 2015 and 2019 on patients diagnosed with PMR. For comparisons, patients with PMR were matched 1:1 to controls based on age and gender. FDG-PET/CT had been completed on the controls over the same period. The FDG uptake was scored visually for 17 articular or periarticular sites and 13 vascular sites using a semi-quantitative scoring system (score of 0-3).

RESULTS

Eighty-one patients with PMR and eighty-one controls were included (mean age 70.7 (9.8) years; 44.4% women). Significant differences between the PMR and control groups were found at all articular and periarticular sites for the following: (i) the FDG uptake score (p < 0.001 for all locations); (ii) the number of patients per site with significant FDG uptake (score ≥ 2); (iii) the global FDG articular uptake scores (31 [IQR, 21 to 37] versus 6 [IQR, 3 to 10], p < 0.001); and (iv) the number of sites with significant FDG uptake (score ≥ 2) (scores of 0-17) (11 [IQR, 7 to 13] versus 1 [IQR, 0 to 2], p < 0.001). No significant differences in the global FDG vascular uptake scores were found between the patients who were considered isolated PMR and the control groups.

CONCLUSIONS

The FDG uptake score and the number of sites with significant FDG uptake could be pertinent criteria for the diagnosis of PMR. Unlike others, we did not confirm the presence of vascular involvement in patients with isolated PMR.

Prognostic factors in giant cell arteritis associated aortitis with PET/CT and CT angiography at diagnosis

BACKGROUND

Prognosis data on giant-cell arteritis (GCA)-associated aortitis are scarce and heterogeneous. The aim of this study was to compare the relapses of patients with GCA-associated aortitis according to the presence of aortitis on CT-angiography (CTA) and/or on FDG-PET/CT.

METHODS

This multicenter study included GCA patients with aortitis at diagnosis; each case underwent both CTA and FDG-PET/CT at diagnosis. A centralized review of image was performed and identified patients with both CTA and FDG-PET/CT positive for aortitis (Ao-CTA+/PET+); patients with positive FDG-PET/CT but negative CTA for aortitis (Ao-CTA-/PET+), and patients solely positive on CTA.

RESULTS

Eighty-two patients were included with 62 (77%) of female sex. Mean age was 67±8 years; 64 patients (78%) were in the Ao-CTA+/PET+ group; 17 (22%) in the Ao-CTA-/PET+ group and 1 had aortitis only on CTA. Overall, 51 (62%) patients had at least one relapse during follow-up: 45/64 (70%) in the Ao-CTA+/PET+ group and 5/17 (29%) in the Ao-CTA-/PET+ group (log rank, p = 0.019). In multivariate analysis, aortitis on CTA (Hazard Ratio 2.90, p = 0.03) was associated with an increased risk of relapse.

CONCLUSION

Positivity of both CTA and FDG-PET/CT for GCA-related aortitis was associated with an increased risk of relapse. Aortic wall thickening on CTA was a risk factor of relapse compared with isolated aortic wall FDG uptake.

Baseline ultrasound and FDG-PET/CT imaging in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a cutaneous tumor with a high tendency to metastasize, and a significant proportion of patients have metastases at first presentation. This study aims to determine the value of baseline ultrasound (US) and ¹⁸ fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸ FDG-PET/CT) imaging in both patients with clinically localized MCC (Stage I/II) and patients who present with palpable lymph nodes (Stage III).

METHODS

This retrospective cohort included 135 MCC patients who underwent baseline US (with fine needle aspiration cytology (FNAC)) and/or FDG-PET/CT imaging between 2015 and 2021.

RESULTS

Of the 104 patients with clinically localized disease, 48% were upstaged to Stage III and 3% to Stage IV by imaging or sentinel lymph node biopsy (SLNB). FDG-PET/CT imaging identified regional metastases in 23%, while US with FNAC identified regional metastases in 19%. SLNB was performed in 56 patients, of whom 57% were upstaged to Stage III. Of the 31 patients who presented with palpable lymph nodes, 16% were upstaged to Stage IV by FDG-PET/CT imaging.

CONCLUSION

Baseline imaging frequently upstages Stage I/II MCC patients to Stage III, both by US and FDG-PET/CT, Stage IV disease is rarely identified. Patients who present with palpable nodes are frequently upstaged to Stage IV by FDG-PET/CT imaging.

Additional Primary Tumors Detected Incidentally on FDG PET/CT at Staging in Patients with First Diagnosis of NSCLC: Frequency, Impact on Patient Management and Survival

We aimed to assess the frequency of additional primary malignancies detected incidentally on [¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) at staging in NSCLC patients. Moreover, their impact on patient management and survival was assessed. Consecutive NSCLC patients with available staging FDG-PET/CT between 2020 and 2021 were retrospectively enrolled. We reported whether further investigations of suspicious findings presumably not related to NSCLC were recommended and performed after FDG-PET/CT. Any additional imaging, surgery or multimodal management was considered as an impact on patient management. Patient survival was defined using overall survival OS and progression-free survival PFS. A total of 125 NSCLC patients were included, while 26 findings in 26 different patients were suspicious for an additional malignancy on FDG-PET/CT at staging. The most frequent anatomical site was the colon. A total of 54.2% of all additional suspicious lesions turned out to be malignant. Almost every malignant finding had an impact on patient management. No significant differences were found between NSCLC patients with suspicious findings versus no suspicious findings with regards to their survival. FDG-PET/CT performed for staging might be a valuable tool to identify additional primary tumors in NSCLC patients. Identification of additional primary tumors might have substantial implications for patient management. An early detection together with interdisciplinary patient management could prevent a worsening of survival compared to patients with NSCLC only.

Heroin Use Is Associated With Vascular Inflammation in Human Immunodeficiency Virus

BACKGROUND

Heroin use may work synergistically with human immunodeficiency virus (HIV) infection to cause greater immune dysregulation than either factor alone. Unraveling how this affects end-organ disease is key as it may play a role in the excess mortality seen in people with HIV (PWH) who use heroin despite access to care and antiretroviral therapy.

METHODS

This is a prospectively enrolled, cross-sectional study of adults with and without HIV who use and do not use heroin using (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to compare tissue-specific inflammation including aortic (target-to-background ratio [TBR]), splenic, and bone marrow (standardized uptake value [SUV]).

RESULTS

A total of 120 participants were enrolled. The unadjusted mean difference in aortic TBR was 0.43 between HIV-positive [HIV+] heroin+ and HIV+ heroin-negative [heroin-] (P = .02); however, among HIV-, aortic TBR was similar regardless of heroin-use status. Further, HIV-by-heroin-use status interaction was significant (P = .02), indicating that the relationship between heroin use and higher aortic TBR depended on HIV status. On the other hand, both HIV (1.54 vs 1.68; P = .04, unadjusted estimated means for HIV+ vs HIV-) and heroin use were associated with lower bone marrow SUV, although the effect of heroin depended on sex (heroin-use-by-sex interaction, P = .03). HIV-by-heroin-use interaction was not significant for splenic or bone marrow SUV.

CONCLUSIONS

Aortic inflammation was greatest in PWH who use heroin, but paradoxically, bone marrow activity was the least in this group, suggesting complex and possibly divergent pathophysiology within these different end organs.

Predicting the pathological invasiveness of early lung adenocarcinoma prior to surgery using Deauville criteria: reliability and validity

PURPOSE

This retrospective study aimed to investigate the validity and reliability of FDG-PET/CT visual assessment using Deauville criteria to predict pathological invasiveness of early lung adenocarcinoma prior to surgery.

MATERIALS AND METHODS

Between April 2020 and January 2022, 51 patients who underwent surgery for pathological stage 0/I lung adenocarcinoma were enrolled. The pulmonary lesions were divided into two groups according to pathological invasiveness: less invasive (including adenocarcinoma in situ and minimally invasive adenocarcinoma and invasive adenocarcinoma. We compared CT size (total and solid size), SUVmax, and Deauville score between the two groups. Furthermore, we investigated inter-rater and intra-rater agreements regarding the Deauville score. Receiver operating characteristic (ROC) curve analysis was performed to identify the diagnostic performance of each method.

RESULTS

Based on pathologic diagnoses, 51 lesions in the 51 patients were divided into 6 less invasive and 45 invasive adenocarcinoma lesions. According to quadratic-weighted Kappa statistics, inter-rater (k = 0.93) and intra-rater (k = 0.97) agreements among all five components of the Deauville score indicated high agreement. There was a statistically significant difference in CT solid size, SUVmax, and Deauville score between the two groups. There were no significant differences between CT solid size and FDG-PET/CT assessments (AUC = 0.93 for Deauville score and SUVmax, AUC = 0.84 for CT solid size).

CONCLUSION

FDG-PET/CT visual assessment using the Deauville score could assist in deciding upon minimally invasive surgery for early lung adenocarcinoma.

Prognostic value of baseline and early response FDG-PET/CT in patients with refractory and relapsed aggressive B-cell lymphoma undergoing CAR-T cell therapy

PURPOSE

Chimeric antigen receptor (CAR)-T cells are a viable treatment option for patients with relapsed or refractory (r/r) aggressive B-cell lymphomas. The prognosis of patients who relapse after CAR-T cell treatment is dismal and factors predicting outcomes need to be identified. Our aim was to assess the value of FDG-PET/CT in terms of predicting patient outcomes.

METHODS

Twenty-two patients with r/r B-cell lymphoma who received CAR-T cell treatment with tisagenlecleucel (n = 17) or axicabtagene ciloleucel (n = 5) underwent quantitative FDG-PET/CT before (PET-0) and 1 month after infusion of CAR-T cells (PET-1). PET-1 was classified as complete metabolic response (CMR, Deauville score 1-3) or non-CMR (Deauville score 4-5).

RESULTS

At the time of PET-1, 12/22 (55%) patients showed CMR, ten (45%) patients non-CMR. 7/12 (58%) CMR patients relapsed after a median of 223 days, three of them (25%) died. 9/10 (90%) non-CMR patients developed relapse or progressive disease after a median of 91 days, eight of them (80%) died. CMR patients demonstrated a significantly lower median total metabolic tumor volume (TMTV) in PET-0 (1 ml) than non-CMR patients (225 ml).

CONCLUSION

Our results confirm the prognostic value of PET-1. 42% of all CMR patients are still in remission 1 year after CAR T-cell treatment. 90% of the non-CMR patients relapsed, indicating the need for early intervention. Higher TMTV before CAR-T cell infusion was associated with lower chances of CMR.

MRI VS. FDG-PET for diagnosis of response to neoadjuvant therapy in patients with locally advanced rectal cancer

Aim

In this study, we aimed to compare the diagnostic values of MRI and FDG-PET for the prediction of the response to neoadjuvant chemoradiotherapy (NACT) of patients with locally advanced Rectal cancer (RC).

Methods

Electronic databases, including PubMed, Embase, and the Cochrane library, were systematically searched through December 2021 for studies that investigated the diagnostic value of MRI and FDG-PET in the prediction of the response of patients with locally advanced RC to NACT. The quality of the included studies was assessed using QUADAS. The pooled sensitivity, specificity, positive and negative likelihood ratio (PLR and NLR), and the area under the ROC (AUC) of MRI and FDG-PET were calculated using a bivariate generalized linear mixed model, random-effects model, and hierarchical regression.

Results

A total number of 74 studies with recruited 4,105 locally advanced RC patients were included in this analysis. The pooled sensitivity, specificity, PLR, NLR, and AUC for MRI were 0.83 (95% CI: 0.77-0.88), 0.85 (95% CI: 0.79-0.89), 5.50 (95% CI: 4.11-7.35), 0.20 (95% CI: 0.14-0.27), and 0.91 (95% CI: 0.88-0.93), respectively. The summary sensitivity, specificity, PLR, NLR and AUC for FDG-PET were 0.81 (95% CI: 0.77-0.85), 0.75 (95% CI: 0.70-0.80), 3.29 (95% CI: 2.64-4.10), 0.25 (95% CI: 0.20-0.31), and 0.85 (95% CI: 0.82-0.88), respectively. Moreover, there were no significant differences between MRI and FDG-PET in sensitivity (P = 0.565), and NLR (P = 0.268), while the specificity (P = 0.006), PLR (P = 0.006), and AUC (P = 0.003) of MRI was higher than FDG-PET.

Conclusions

MRI might superior than FGD-PET for the prediction of the response of patients with locally advanced RC to NACT.

Persistent pain and numbness in the extremities of an adult due to paraneoplastic peripheral neuropathy caused by olfactory neuroblastoma: A case report

Background

Paraneoplastic peripheral neuropathy (PPN) caused by olfactory neuroblastoma (ONB) has not yet been reported.

Case report

We present a rare case of an adult who hospitalized repeatedly over the past 9 months for persistent pain and numbness in the limbs. This patient was initially diagnosed with chronic inflammatory demyelinating polyneuropathy (CIDP) and treated accordingly, but neurological symptoms did not improve significantly. After this admission, FDG-PET/CT showed focal hypermetabolism of a soft-tissue mass in the nasal cavity, and further lesion biopsy suggested ONB. Combined with positive serum anti-Hu antibody, the diagnosis of PPN associated with ONB was eventually made. Furthermore, the patient's neurological symptoms were relieved after removal of the primary tumor, confirming the accuracy of the diagnosis.

Conclusion

Our case not only expanded the clinical characteristics of ONB but also highlighted the importance of early and comprehensive tumor screening for the diagnosis of PPN.

Liver adenomatosis mimics metastatic liver involvement on FDG-PET/ CT

BACKGROUND

Liver adenomatosis is a very rare disease. In the literature, we were able to find only two case reports documenting the appearance of this disease on PET/CT with 18F-fludeoxyglucose (FDG-PET/CT).

CASE

Numerous liver foci were detected during sonography in a 52-year-old female patient with uncharacteristic pain in the epigastrium without oncological history, with negative oncomarkers and without clinical signs of generalized neoplasia. Complementary MRI examination expressed the suspicion of metastatic origin of the foci, and FDG-PET/CT was indicated in order to identify the primary tumour and assess the extent of the disease. A whole-body FDG-PET/CT examination showed multiple (&gt; 20) markedly hypermetabolic liver foci with 3-20 mm in diameter, reaching a relative accumulation of SUVBWmax = 13, together with several ametabolic cysts; elsewhere in the scope of the examination, focally pathologically increased metabolic activity was not evident. Subsequently, the patient underwent a biopsy targeted at one of the hypermetabolic liver foci with the finding of HNF 1A inactivated variant of hepatocellular adenoma; primary or secondary malignancy was not demonstrated. Considering the histological findings and the large number of liver foci, the final diagnosis of liver adenomatosis was set. The patient remains under continuous observation.

CONCLUSION

Adenomatous foci were markedly hypermetabolic during FDG-PET/CT examination and could not be distinguished from tumour metastases by this method. Our finding is consistent with two other observations we were able to find in the literature.

[A case of giant cell arteritis after prednisolone dose reduction during treatment of polymyalgia rheumatica]

Giant cell arteritis (GCA) is closely associated with polymyalgia rheumatica (PMR). We herein report an 82-year-old woman who developed GCA during PMR treatment. She initially presented with shoulder pain and was diagnosed with PMR based on elevated serum C-reactive protein (CRP) levels and bursitis detected in both shoulders on ultrasonography (US). Treatment was initiated with a daily dose of 15 mg prednisolone (PSL), which led to rapid symptom alleviation, and the dosage was tapered to 1 mg/day. One month later, she developed myalgia extending from the lumbar region to the thigh and tenderness in the left temporal region. However, no abnormalities in the temporal artery were observed on US. Although the PSL dose was increased to 2 mg for relapse of PMR, the symptoms did not improve. One week later, she developed occipital pain with an increased CRP level of 9 mg/dL. She was diagnosed with GCA based on the 1990 ACR Classification Criteria. Fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) detected anomalous accumulations in the bilateral superficial temporal and vertebral arteries, but not in the larger vessels. We therefore diagnosed her with cranial-type GCA. At this time point, we repeated US and found a halo sign in the temporal artery. Although epithelioid and giant cells were not observed in the temporal artery biopsy, vascular inflammatory findings such as disruption of the internal elastic lamina and chronic inflammatory cell infiltration were noted. Symptoms improved immediately and CRP levels decreased after the PSL dose was increased to 30 mg daily. To mitigate the risk of steroid-induced diabetes, tocilizumab was introduced, and gradual tapering of PSL was implemented. In conclusion, we encountered a case of GCA that developed after PSL reduction during the course of PMR. PET/CT confirmed intracranial artery inflammation and facilitated a definitive diagnosis. Although PET/CT cannot be routinely performed for diagnose in Japan, we consider it useful as an adjunctive diagnostic tool.

Accuracy of FDG-PET/CT for Response Evaluation of Muscle-Invasive Bladder Cancer following Neoadjuvant or Induction Chemotherapy

INTRODUCTION

The aim of the study was to confirm the diagnostic accuracy of a second FDG-PET/CT following neoadjuvant or induction chemotherapy (NAIC) prior to radical cystectomy for patients with localized muscle-invasive bladder cancer (MIBC).

METHODS

Retrospective review of 62 consecutive patients with MIBC, that had a first FDG-PET/CT between April 2016 and September 2021. Patients then underwent NAIC, followed by a second FDG-PET/CT and radical cystectomy. Patients with no hypermetabolism in the bladder and lymph nodes on the second FDG-PET/CT were considered metabolic complete responders, while patients with no evidence of residual disease on histopathology were considered pathologic complete responders. The accuracy of the second FDG-PET/CT to distinguish complete responders from patients with residual disease was calculated, with histopathology as gold standard.

RESULTS

Of 62 patients, 1 was lost to follow-up, 5 died before radical cystectomy, 5 had delay >2 months between the second FDG-PET/CT and radical cystectomy, and 6 did not undergo radical cystectomy and instead underwent alternative treatment. The study cohort comprised 45 patients, 39 males and 6 females, with an age of 66 ± 6 years. In comparison to histopathology, FDG-PET/CT provided (i) sensitivity of 95% and specificity of 42%, for the overall disease; (ii) sensitivity of 100% and specificity of 36%, for the primary tumor only; and (iii) sensitivity of 97% and specificity of 30%, for the lymph nodes only.

CONCLUSION

FDG-PET/CT has over 95% sensitivity for distinguishing complete responders from patients with residual disease. Thus, FDG-PET/CT can be used for early response evaluation following NAIC to identify patients that did not completely respond to chemotherapy and may require alternative treatment pathways.

Mixed neuroendocrine carcinoma and hepatocellular carcinoma in the liver

BACKGROUND

Mixed neuroendocrine carcinoma (NEC) and hepatocellular carcinoma (HCC) is extremely rare, thus radiological features have not been fully clarified.

CASE

A male patient (age: 70 years) visited our hospital due to a tumor in the liver. Examination using contrast-enhanced computed tomography (CT) revealed a tumor (diameter: 5.0 cm) in hepatic segment 5, with early enhancement of the peripheral area and slight internal heterogeneous enhancement in the arterial and delayed phases, respectively. F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT revealed intratumoral heterogeneity, characterized by increased uptake (standardized uptake value, 12.10) in the corresponding low-density area detected using enhanced CT relative to the surrounding areas of the tumor. On magnetic resonance imaging, diffusion-weighted imaging also showed high intensity in the corresponding low-density area detected using CT. Preoperatively, the patient was diagnosed with HCC and underwent anterior sectionectomy. Pathological findings revealed both HCC and NEC components, and the patient was diagnosed with mixed NEC and HCC. Comparison of component distribution with FDG-PET/CT revealed an increased uptake area was congruent with the NEC component in the tumor.

CONCLUSION

In this case, the difference in tumor components affected the uptake in FDG-PET/CT. Such heterogeneous uptake with an enhanced spot may be useful for suspecting the presence of mixed NEC and HCC in patients with atypical HCC.

Usefulness of serum S100A4 and positron-emission tomography on lung cancer accompanied by interstitial pneumonia

BACKGROUND

The S100 calcium-binding protein A4 (S100A4) and the accumulation of [18F]-fluoro-2-deoxy-D-glucose (FDG) in noncancerous interstitial pneumonia (IP) area are predictors of postoperative acute exacerbation (AE) of IP after pulmonary resection for lung cancer with IP. However, the significance of combining these markers for predicting short-term outcome and long-term prognosis is not known.

METHODS

Patients diagnosed with IP on preoperative high-resolution computed tomography and who had undergone pulmonary resection for primary lung cancer between April 2010 and March 2019 at Hiroshima University were included in this study. Predictive factors for the cumulative incidence of death from other than lung cancer (CIDOL) were investigated using the Fine and Gray model. CIDOL, perioperative outcome, and cumulative incidence of all death (CIAD) were retrospectively compared based on serum S100A4 and FDG accumulation.

RESULTS

A total of 121 patients were included in this study. High S100A4 (hazard ratio [HR], 2.541; p = 0.006) and FDG accumulation (HR, 3.199; p = 0.038) were significant predictors of CIDOL. AE of IP occurred only in patients with high S100A4/FDG (+). CIDOL of patients with high S100A4/FDG (+) was higher than those with high S100A4/FDG (-) or low S100A4/FDG (+) (p < 0.001), and CIAD of patients with high S100A4/FDG (+) was also higher than those with high S100A4/FDG (-) or low S100A4/FDG (+) patients (p = 0.021).

CONCLUSIONS

Serum S100A4 and FDG accumulation in the noncancerous IP area were significant predictors of CIDOL after lung resection for lung cancer with IP and may help decide the treatment strategy.

Vascular/perivascular inflammation in IgG4-related disease

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is characterized by the infiltration of IgG4-positive plasma cells and fibrosclerotic inflammation in multiple organs. Although vascular complications are present in some patients with IgG4-RD, vascular and/or perivascular inflammatory activity compared to control subjects remains unknown. This study sought to investigate vascular/perivascular inflammation in IgG4-RD patients compared to control subjects using 18F-fluorodeoxyglucose-positron emission tomography combined with computed tomography (FDG-PET/CT).

METHODS

We examined 37 consecutive patients diagnosed as IgG4-RD (29 males, mean age of 64.3 ± 8.3 years old), who underwent FDG-PET/CT. Thirty-seven age- and gender-matched subjects without IgG4-RD were employed as controls. Vascular/perivascular inflammation was quantified by blood-normalized standardized uptake value, known as a target-to-background ratio (TBR).

RESULTS

All IgG4-RD patients presented with multiple region involvements. Twelve (32.4%) of the IgG4-RD patients had vascular complications, all of which appeared in the abdominal aorta. IgG4-RD patients had significantly higher TBR values in the descending aorta, abdominal aorta, and common iliac artery than control subjects. Also, IgG4-RD patients with vascular complication exhibited higher TBR values in the infra-renal aorta and common iliac artery than those without vascular complication.

CONCLUSIONS

We found that vascular FDG activity is significantly elevated in IgG4-RD patients regardless of vascular complication than control subjects. FDG-PET/CT is a useful modality for assessing vascular/perivascular inflammation, which may contribute vascular complication in IgG4-RD patients.

Anti-inflammatory effect of rosuvastatin in patients with HIV infection: An FDG-PET pilot study

AIMS

This study aimed to evaluate markers of systemic as well as imaging markers of inflammation in the ascending aorta, bone marrow, and spleen measured by 18F-FDG PET/CT, in HIV+ patients at baseline and following therapy with rosuvastatin.

METHODS AND RESULTS

Of the 35 HIV+ patients enrolled, 17 were randomized to treatment with 10 mg/day rosuvastatin and 18 to usual care for 6 months. An HIV- control cohort was selected for baseline comparison of serum inflammatory markers and monocyte markers of inflammation. 18F-FDG-PET/CT imaging of bone marrow, spleen, and thoracic aorta was performed in the HIV+ cohort at baseline and 6 months. While CD14++CD16- and CCR2 expressions were reduced, serum levels of IL-7, IL-8, and MCP-1 were elevated in the HIV+ population compared to the controls. There was a significant drop in FDG uptake in the bone marrow (TBRmax), spleen (SUVmax) and thoracic aortic (TBRmax) in the statin-treated group compared to the control group (bone marrow: - 10.3 ± 16.9% versus 5.0 ± 18.9%, p = .0262; spleen: - 9.8 ± 20.3% versus 11.3 ± 28.8%, p = .0497; thoracic aorta: - 19.1 ± 24.2% versus 4.3 ± 15.4%, p = .003).

CONCLUSIONS

HIV+ patients had significantly markers of systemic inflammation including monocyte activation. Treatment with low-dose rosuvastatin in the HIV+ cohort significantly reduced bone marrow, spleen and thoracic aortic FDG uptake.

Incidental FDG-Avid Focuses in Palatine Tonsils on PET/CT

OBJECTIVES

The management of incidental findings of FDG-avid tonsils on PET/CT (IFT) is unclear. We aimed to explore the prevalence of malignancy in IFT, identify risk factors for malignancy, and calculate optimal cutoffs of maximum standardized uptake values (SUV_max ) to discriminate between benign and malignant lesions.

METHODS

All patients who were tonsillectomized at our institution because of IFT from October 2011 to December 2020 were included. Patients undergoing PET/CT due to suspected tonsillar disease or cancer of unknown primary were excluded.

RESULTS

In total, 77 patients were included, of which 11 (14%) of them had IFT malignancy. Dysphagia (p = 0.019) and alcohol abuse (p = 0.035) were associated with malignancy. Absolute SUV_max cutoff (≥9: sensitivity 100%; specificity 53%) was superior to SUV_max side-to-side ratio (≥1.5: sensitivity 64%; specificity 70%) to discriminate between benign and malignant lesions.

CONCLUSION

We recommend tonsillectomy for patients with IFT displaying SUV_max  ≥ 9.0, ratio ≥ 1.5, or symptoms or findings suggesting malignancy.

LEVEL OF EVIDENCE

3 Laryngoscope, 132:2370-2378, 2022.

[(18)F]-Fludeoxyglucose Positron Emission Tomography/Computed Tomography with Radiomics Analysis in Patients Undergoing Aortic In-Situ Reconstruction with Cryopreserved Allografts

BACKGROUND

The aim of this study was to evaluate the effectiveness of positron emission tomography/computed tomography with [¹⁸F]-fludeoxyglucose (FDG-PET/CT) and radiomics analysis in detecting differences between the native aorta and the abdominal aortic allograft after the total eradication of infection in patients undergoing infected graft removal and in situ reconstruction with cryopreserved allografts.

METHODS

Between January 2008 and December 2018, 56 vascular reconstructions with allografts have been performed at our department. The present series included 12 patients undergoing abdominal aortic in situ reconstruction with cryopreserved allografts. During the follow-up, all patients underwent a total-body [¹⁸F]FDG PET/CT with subsequent radiomics analysis. In all patients, a comparative analysis between the data extracted from native aorta and cryopreserved graft for each patient was performed.

RESULTS

All patients were male with a mean age of 72.8 years (range 63-84). Mean duration of follow-up was 51.3 months (range 3-120). During the follow-up, 2 patients (16.7%) needed a redo allograft-related surgical intervention. Overall, the rate of allograft dilatation was 33.3%. No patient had a redo infection during the follow-up. Radiomics analysis showed a different signature of implanted allograft and native aorta. Comparative analysis between the native aortas and cryopreserved allografts (dilated or not) showed several statistical differences for many texture features.

CONCLUSIONS

The higher metabolic activity of allografts could indicate a state of immune-mediated degeneration. This theory should be proven with prospective, multicentric studies with larger sample sizes.

ACR Appropriateness Criteria® Staging and Follow-Up of Esophageal Cancer

This document provides recommendations regarding the role of imaging in the staging and follow-up of esophageal cancer. For initial clinical staging, locoregional extent and nodal disease are typically assessed with esophagogastroduodenoscopy and esophageal ultrasound. FDG-PET/CT or CT of the chest and abdomen is usually appropriate for use in initial clinical staging as they provide additional information regarding distant nodal and metastatic disease. The detection of metastatic disease is critical in the initial evaluation of patients with esophageal cancer because it will direct patients to a treatment pathway centered on palliative radiation rather than surgery. For imaging during treatment, particularly neoadjuvant chemotherapy, FDG-PET/CT is usually appropriate, because some studies have found that it can provide information regarding primary lesion response, but more importantly it can be used to detect metastases that have developed since the induction of treatment. For patients who have completed treatment, FDG-PET/CT or CT of the chest and abdomen is usually appropriate for evaluating the presence and extent of metastases in patients with no suspected or known recurrence and in those with a suspected or known recurrence. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.