Incidental Uptake Research Articles

Clinical scenarios of unusual FDG uptake in muscle.

Glucose is essential for muscle function and its uptake is influenced by aerobic conditions, hormonal regulations, and exercise. 18F-Fluorodeoxyglucose (FDG), a glucose analog used in PET/CT scans, can show incidental uptake in muscles, and thus careful interpretation is required to avoid misdiagnosis. Proper patient preparation and understanding of the clinical scenarios affecting FDG uptake are crucial for accurate PET/CT interpretation, thus ensuring precise diagnoses and avoiding unnecessary interventions. This review emphasizes the need to consider patient-specific factors in evaluating incidental FDG uptake in muscle.

Incidental Uptake in Gastrointestinal Tract on 18F-FDG-PET/CT: Is It Worth to Investigate? A Study with 371 Patients

Background and Study Aims: Positron emission tomography/computed tomography (PET/CT) with 2-[18F]FDG (FDG) has been increasingly used to detect or monitor neoplasms. Gastrointestinal tract (GIT) is one of the most common sites of FDG uptake, leading to increasing requests for endoscopic examinations. We aimed to evaluate the nature and significance of unexpected PET/CT-FDG findings in the GIT. Patients and Methods: We retrospectively analyzed 371 consecutive patients with incidental GIT findings on PET/CT-FDG between June 2016 and October 2021 who were subsequently referred to endoscopic examinations. Demographic data, PET/CT-FDG results, endoscopic findings, and histological analysis were analyzed. Results: Of 194 colonic incidental uptakes, 102 (52.6%) corresponded to at least premalignant lesions, being 57 (29.4%) advanced adenomas and 23 (11.9%) adenocarcinomas. Of 193 upper GIT incidental uptakes, there were 11 (13.8%) esophageal and 14 (14.4%) gastric malignant/premalignant lesions. The maximum standardized uptake value (SUVmax) significantly varied according to the nature of the lesion, being higher in malignant lesions (in the esophagus, stomach, and colon). However, an optimal SUVmax cutoff was only found for stomach (SUVmax 8.2; sensitivity of 79% and specificity of 76%). There was a significant association between the site of uptake and the nature of the lesion – left colon and gastric body uptake were associated with neoplastic origin whereas rectum and lower esophagus were associated with inflammatory or no endoscopic changes. Conclusions: Any incidental uptake in the lower GIT should be investigated provided that patients are suitable for further treatment. However, in the upper GIT the characteristics of uptake on 18F‐FDG‐PET/CT may allow to select those who need endoscopic examination.

18F]FDG PET-TC radiomics and machine learning in the evaluation of prostate incidental uptake

ABSTRACT Aim To evaluate the relevance of incidental prostate [18F]FDG uptake (IPU) and to explore the potential of radiomics and machine learning (ML) to predict prostate cancer (PCa). Methods We retrieved [18F]FDG PET/CT scans with evidence of IPU performed in two institutions between 2015 and 2021. Patients were divided into PCa and non-PCa, according to the biopsy. Clinical and PET/CT-derived information (comprehensive of radiomic analysis) were acquired. Five ML models were developed and their performance in discriminating PCa vs non-PCa IPU was evaluated. Radiomic analysis was investigated to predict ISUP Grade. Results Overall, 56 IPU were identified and 31 patients performed prostate biopsy. Eighteen of those were diagnosed as PCa. Only PSA and radiomic features (eight from CT and nine from PET images, respectively) showed statistically significant difference between PCa and non-PCa patients. Eight features were found to be robust between the two institutions. CT-based ML models showed good performance, especially in terms of negative predictive value (NPV 0.733–0.867). PET-derived ML models results were less accurate except the Random Forest model (NPV = 0.933). Radiomics could not accurately predict ISUP grade. Conclusions Paired with PSA, radiomic analysis seems to be promising to discriminate PCa/non-PCa IPU. ML could be a useful tool to identify non-PCa IPU, avoiding further investigations.

Estimated population prevalence of cardiac transthyretin amyloidosis as an incidental finding on bone scintigraphy in a university hospital in Colombia

Abstract Background Cardiac uptake in bone scintigraphy is highly sensitive and specific for transthyretin cardiac amyloidosis (ATTR), allowing a useful noninvasive diagnostic pathway even before echocardiographic or electrocardiographic abnormalities are present. Early diagnosis translates into early treatment and, thus, improves morbidity and mortality. In Colombia, ATTR diagnosis is still delayed or missed, and no studies have described incidental cardiac uptake on bone scintigraphy. Regarding health resources, the economic impact derived from the treatment of CA in Latam requires rigorous patient selection. This study aims to bridge this gap and improve the local clinical context. Methods We performed a retrospective cohort study which included all patients older than 65 who underwent bone scintigraphy using 99m Technetium labeled hydroxy-methylene- diphosphonate (HMDP) between January 2020 to December 2022 at our institution. Two independent physicians screened the bone scans, which a Nuclear Imaging specialist following the American Society of Nuclear Radiology guidelines then graded. Bone scans indicated for suspicion of ATTR were excluded. The prevalence of cardiac uptake and demographic characteristics were assessed. Results A total of 1206 patients were analyzed. Thirty-eight were excluded due to suspected CA. The study population, therefore, consisted of n=1168 patients with musculoskeletal (58%) and oncologic (40%) indications for scintigraphy. 55% of the sample were men; the median age was 75. Cardiac uptake was found in 1.5% of patients, from which 28% had Grade Perugini 1, 17% had Grade Perugini 2, and 56% had Grade Perugini 3. Among patients with incidental uptake, 78% were men, with a median age of 84 years; 17% had heart failure, 11% had aortic stenosis, 11% had dysautonomia, 6% had polyneuropathy, 22% had spinal stenosis, and 17% had carpal tunnel syndrome. Conclusion We describe the first South American cohort of incidental cardiac uptake in HMDP scintigraphy. The observed incidence in this cohort was 1.5%, in concordance with previously published data in other continents. Bone scintigraphy is highly available in all regions of Colombia, allowing the identification of subclinical ATTR before severe functional impairment occurs and prompt treatment initiation in CA patients. The development of reference centers for the healthcare of CA patients allows the incorporation of clinical pathways that facilitate the approach of patients with incidental myocardial uptake in bone scans requested for non-cardiac causes, which warrant further clinical assessment and follow-up.Clinical characteristicsIncidental cardiac uptake

Incidental FAPI Localization in Benign Bone Lesions in a Case of Carcinoma Stomach.

Recently developed radiolabeled FAPI (fibroblast-activation protein inhibitors) have attracted researcher's attention in diagnosing various tumors because of its high specificity and better tumor-to-background ratio. Increasing use of 68Ga-FAPI PET/CT has resulted in reporting of incidental benign findings as well. We hereby present a case of suspected carcinoma stomach showing increased uptake in primary tumor in stomach as well as incidental uptake in benign subchondral cysts in bilateral shoulder joints and right hip joint on 68Ga-FAPI PET CT scan.

Gallium-68 fibroblast activation protein inhibitor positron emission tomography in cardiovascular disease.

Gallium-68 fibroblast activation protein inhibitor [(68Ga)Ga-FAPI] is a new radiopharmaceutical positioning itself as the preferred agent in patients with malignant tumours, competing with 2-Deoxy-2-[18F]fluoro-d-glucose [2-(18F)FDG] using positron emission tomography (PET). While imaging oncology patients with [68Ga]Ga-FAPI PET, incidental uptake of [68Ga]Ga-FAPI has been detected in the myocardium. This review summarises original research studies associating the visualisation of FAPI-based tracers in the myocardium with underlying active cardiovascular disease.

18F-FDG PET and CT identifiers of high-risk lesions in the stomach and esophagus.

e16036 Background: Assessing the significance of incidentally found increased 18F-FDG uptake in the stomach and esophagus on PET/CT has long been a challenge. Currently, there is no clear guideline to assist clinicians with distinguishing malignant from benign uptake. This study aims to compare various PET and CT characteristics used separately and collectively, to identify high-risk foci of uptake. Methods: 18F-FDG PET/CT images from August 2018 to October 2022 were reviewed and patients who completed a follow up EGD due to incidentally found increased gastroesophageal uptake were included in this study. To identify high-risk foci, the following PET and CT characteristics were used: 1) uptake intensity, using lesion SUVmax relative to mediastinal blood pool and liver SUVmean values (≤ blood pool = 0, > blood pool but < liver = 1, ≥ liver = 2); 2) uptake pattern (diffuse = 0, segmental = 1, focal = 2); 3) eccentricity (circumferential= 0, eccentric = 1); and CT correlation score (normal = 0, thickening = 1, mass = 2). Cut-off values were determined using receiver operating characteristic (ROC) curves. Benign and malignant uptake were compared to histological findings using Pearson’s chi-square test. Results: Incidental uptake in the stomach and/or esophagus were noted in 473/7805 (6.1%) patients of which 89 (18.8%) had a follow up EGD and were included in this study. Uptake intensity did not differentiate benign and malignant as SUVmax was greater than background tissues in all cases (Score =2). Uptake pattern, eccentricity, and CT-correlation of PET were significantly different between benign and malignant foci ( p < 0.001, p < 0.001, and p < 0.001, Chi-square). Using cut-off scores from ROC curves, the predictive value of different PET/CT characteristics in identifying high-risk foci was reviewed. Conclusions: PET eccentricity along with anatomic CT correlative findings, offer similar value in predicting high-risk uptake foci to uptake pattern, eccentricity, and CT correlation combined. These are both, however, superior to other PET/CT characteristics used alone or in combination. [Table: see text]

Prevalence and clinical significance in our setting of incidental uptake in the thyroid gland found on 18F-fluordeoxyglucose positron emission tomography-computed tomography (PET-CT)

IntroductionThe expanding use of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has resulted in an increased frequency of incidentally discovered areas of FDG uptake within the thyroid gland. In these incidentalomas, high malignancy rates are reported. The study aimed, on the one hand, to determine the prevalence in our setting of thyroid incidentalomas in patients with no previous history of thyroid cancer undergoing an FDG PET-CT as well as the risk of malignancy and, on the other hand, to evaluate the usefulness of the maximum standard uptake value (SUVmax) for detecting thyroid cancer. Material and methodsThe FDG PET-CT scans performed at our hospital between June 2013 and December 2020 were retrospectively reviewed. In those incidentalomas with sufficient additional investigation, a diagnosis of benign or malignant was established based on the complementary tests. ResultsFrom the 21,594 PET-CT scans performed, 398 (1.8%) patients had an incidental FDG uptake, either focal (n=324) or diffuse (n=74). Among incidentalomas with further investigation, the rate of malignancy was higher in patients with focal FDG uptake than in those with diffuse uptake (26.5% versus 4%, respectively, p<0.05). The SUVmax value was significantly lower in benign focal lesions (5.7 [range: 2.3–66] than in malignant ones 10.6 [range: 3.1–51.2]; p<0.05). Nearly a quarter of malignant diagnoses (23.3%) were related to potentially aggressive tumours. ConclusionThe high rate of malignant tumours found among PET-CT incidentalomas and the high proportion of aggressive tumours demonstrate the need for a standardised approach in the investigation of incidental focal FDG uptake in the thyroid gland.

Using Ion Substitution and Fluid Indicators to Monitor Macropinosome Dynamics in Live Cells.

All forms of endocytosis involve the incidental uptake of fluid (pinocytosis). Macropinocytosis is a specialized type of endocytosis that results in the bulk ingestion of extracellular fluid via large (>0.2μm) vacuoles called macropinosomes. The process is a means of immune surveillance, a point of entry for intracellular pathogens, and a source of nutrients for proliferating cancer cells. Macropinocytosis has also recently emerged as a tractable system that can be experimentally exploited to understand fluid handling in the endocytic pathway. In this chapter, we describe how stimulating macropinocytosis in the presence of extracellular fluids of a defined ionic composition can be combined with high-resolution microscopy to understand the role of ion transport in controlling membrane traffic.

Prevalence and clinical significance in our setting of incidental uptake in the thyroid gland found on 18F-fluordeoxyglucose positron emission tomography-computed tomography (PET-CT)

IntroductionThe expanding use of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) has resulted in an increased frequency of incidentally discovered areas of FDG uptake within the thyroid gland. In these incidentalomas, high malignancy rates are reported. The study aimed, on the one hand, to determine the prevalence in our setting of thyroid incidentalomas in patients with no previous history of thyroid cancer undergoing an FDG PET-CT as well as the risk of malignancy and, on the other hand, to evaluate the usefulness of the maximum standard uptake value (SUVmax) for detecting thyroid cancer. Material and methodsThe FDG PET-CT scans performed at our hospital between June 2013 and December 2020 were retrospectively reviewed. In those incidentalomas with sufficient additional investigation, a diagnosis of benign or malignant was established based on the complementary tests. ResultsFrom the 21,594 PET-CT scans performed, 398 (1.8%) patients had an incidental FDG uptake, either focal (n=324) or diffuse (n=74). Among incidentalomas with further investigation, the rate of malignancy was higher in patients with focal FDG uptake than in those with diffuse uptake (26.5% versus 4%, respectively, p<0.05). The SUVmax value was significantly lower in benign focal lesions (5.7 [range: 2.3–66] than in malignant ones 10.6 [range: 3.1–51.2]; p<0.05). Nearly a quarter of malignant diagnoses (23.3%) were related to potentially aggressive tumours. ConclusionThe high rate of malignant tumours found among PET-CT incidentalomas and the high proportion of aggressive tumours demonstrate the need for a standardised approach in the investigation of incidental focal FDG uptake in the thyroid gland.

Clinico-pathological correlation of incidental focal colorectal uptake on 18F-Labelled 2-fluoro-2-Deoxyglucose PET/CT: A prospective single centre experience

ObjectivesTo assess the clinical and pathological implications of incidental focal uptakes during the 18F-FDG-PET/CT colorectal examination and the role of colonoscopy in the diagnostic algorithm of these uptakes. MethodsWe performed a single-center prospective that recruited patients with incidental uptakes during18F-FDG-PET/CT colorectal examination over five years. Patients underwent colonoscopy and biopsies to assess the usefulness of 18F-FDG-PET/CT in patients with incidental uptakes. ResultsA total of 2231 scans were performed, and 71 (3.18%) localized colorectal uptakes were identified. The colon was normal in 45.07% of these uptakes, while the remaining cases had malignant colorectal tumors (29.57%) and neoplastic lesions (25.35%). The false-positive rate was significantly higher in the proximal colon than in the distal colorectal (53.7% vs. 39.8%, P = 0.004). The bivariate analysis showed that increased SUVmax independently increases the risk of neoplastic lesions, while proximal colon uptakes independently decrease the risk of neoplastic lesions. ConclusionsOur results highlight a valuable role of incidental focal uptakes during 18F-FDG-PET/CT colorectal examination in identifying patients with increased risk of neoplastic lesions. The study supports the need for a colonoscopy in such settings, particularly with increased SUVmax.

Non-oncologic incidental uptake on FAPI PET/CT imaging.

Fibroblast-activation protein (FAP) is a serine protease classified in the dipeptidyl peptidase 4 (DPP4) family. FAP is predominantly expressed in activated fibroblasts such as the cancer-associated fibroblasts (CAFs). FAP expression in CAFs is associated with tumor progression and poor prognosis in solid cancers. Recently, radiolabeled FAP inhibitors (FAPI) has been developed, which enables positron emission tomography (PET) imaging of FAP. FAPI PET/CT can provide a higher tumor-to-background ratio (TBR) than 18F-fludeoxyglucose PET/CT in various cancers, and thus has attracted substantial attention. As studies on FAPI PET grow in number and size, incidental findings related to non-oncologic conditions have been increasingly reported. FAPI PET uptake has been reported in various conditions such as benign tumors, fibrotic, granulomatosis, scarring/wound, degenerative diseases, and inflammatory diseases.The knowledge of physiological and non-oncologic causes of FAPI uptake is indispensable for accurate FAPI PET/CT interpretation and can help appropriate management of incidental findings on FAPI PET/CT in patients referred for cancer staging indications. In this review article, we describe for each organ system (Brain, Oral mucosa, Salivary Glands, Thyroid, Lung, Myocardium, Breast, Esophagus, Stomach, Intestine, Liver, Gallbladder, Pancreas, Spleen, Kidney, , Uterus, Bone marrow, Joints, Muscle, Vessels, Lymph nodes), the patterns of physiological FAPI uptake and the main causes of non-oncological uptake reported from the literature with FAPI-02, FAPI-04 and FAPI-46. We also illustrate some examples from our institutional database at UCLA.

Prevalence of Brain Incidental Lesions Detected by 68Ga-DOTA Peptides PET/CT.

Background and Objectives: 68Ga-DOTA peptides positron emission tomography/computed tomography (PET/CT) is usually applied for the study of neuroendocrine tumours, but other tumours such as meningioma may also have an increased radiopharmaceutical uptake. The aim of this retrospective study was to establish the prevalence and the meaning of brain incidental uptake among patients who performed 68Ga-DOTA peptides PET/CT for other reasons. Materials and Methods: Overall, 510 68Ga-DOTA peptides PET/CT scans performed between January 2018 and February 2022 from 430 patients were reviewed for the analysis of incidental brain radiopharmaceutical uptake. All brain incidentalomas were compared with brain magnetic resonance imaging (MRI) and/or contrast-enhanced CT performed within an average time interval of ±60 days from PET/CT scan. Results: A total of 48 patients (14%) presented incidental focal intracranial radiotracer uptake. Thirty-eight (11%) of them had a suspected meningioma confirmed by MRI or contrast-enhanced CT imaging features. The remaining 10 had a final diagnosis different from meningioma (5 as brain metastases and 2 as venous anomalies) or were lost during the follow-up without performing MRI (n = 3). The average maximal standardized uptake value (SUVmax) of the suspected meningioma was 16.5 (range 5–33), and the average lesion to brain SUVmax ratio was 351 (range 80–550). Conclusions: Brain incidental uptake from the 68Ga-DOTA peptides PET/CT is not so rare, and meningioma is the most frequent cause.

Thyroid incidental uptake at 18F-FDG PET/CT, an alert to malignancy - a case report

Thyroid incidental uptake at 18F-FDG PET/CT, an alert to malignancy - a case report

Physiological tracer distribution and benign lesion incidental uptake of Al18F-NOTA-FAPI-04 on PET/CT imaging.

To systematically investigate the physiological distribution and benign lesion incidental uptake of Al18F-NOTA-FAPI-04 (18F-FAPI) in cancer patients to establish the normal uptake range in relevant organs and lesions. Twenty patients who underwent 18F-FAPI PET/CT imaging were retrospectively assessed. Organ and benign lesion tracer uptake was quantified based on standardized uptake values (SUVmax and SUVmean). We compared the variation in tracer uptake in certain organs between men and women, analyzed the possible reasons for diffuse uptake in the thyroid, and assessed tracer uptake variations in the uterus in different menstrual cycle phases. Incidental tracer uptake in benign lesions was also assessed. Physiological 18F-FAPI uptake was observed in the urinary tract, biliary tract system, submandibular glands, pancreas, thyroid, uterus, intestine, prostate gland, parotid gland, myocardium, kidney cortex, and muscles, but not the brain, lungs, liver, spleen, colon, and breasts. The SUVmean for each organ was similar for women and men (all P > 0.05). Diffuse tracer uptake in the thyroid was caused by normal thyroid or thyroiditis; there were no statistically significant differences between them (SUVmax: t = -1.3, P = 0.25; SUVmean: t = -1.1, P = 0.31). There was a significant difference for uterus uptake among different menstrual cycle phases (SUVmax: F = 5.08, P = 0.04; SUVmean: F = 5.19, P = 0.04). Incidental benign lesion tracer uptake was observed in patients with esophagitis, thyroiditis, arthritis, fractures, and uterine fibroids. This study provides a reference range for 18F-FAPI uptake in relevant organs and benign lesions. Benign lesion 18F-FAPI uptake may reduce 18F-FAPI PET/CT specificity.

Suspicious cold thyroid nodule with intense focal 68Ga-DOTATATE uptake: a case report

A 51-year-old male was found with bilateral thyroid nodules on ultrasonography neck imaging. The largest nodule, measuring 23 × 26 × 35 mm, was located in the left lobe and was classified as EU-TIRADS 4. Thyroid function tests were normal, as were serum levels of parathormone, Chromogranin A, carcinoembryonic antigen and calcitonin. The nodule was cold on thyroid scintigraphy. Fine-needle aspiration of the nodule did not demonstrate cellular atypia. High focal uptake was found on both 111In-DTPA-octreotide scintigraphy and 68Ga-DOTATATE PET/CT. Histopathological analysis showed a microfollicular adenoma without malignancy. Immunohistochemical staining did not suggest neuroendocrine neoplasia or C cell hyperplasia. However, high expression of somatostatin receptor 2 (SSTR2) was observed in the microfollicular adenoma compared to the surrounding healthy tissue, with predominant localization in the endothelial cells and at the secretory pole of the thyroid epithelial cells in contact with blood vessels. High focal thyroid uptake on 68Ga-DOTATATE PET/CT can be observed in benign thyroid nodules due to an overexpression of SSTR by endothelial cells. However, incidental focal thyroid uptake on SSTR imaging requires further investigations to rule out thyroid malignancy.

Retrospective analysis of PSMA PET/CT thyroid incidental uptake in adults: incidence, diagnosis, and treatment/outcome in a tertiary cancer referral center and University Medical Center.

A prostate-specific membrane antigen (PSMA) thyroid incidentaloma (PTI) is an unexpected, PSMA-avid thyroid lesion, newly detected during the investigation of an unrelated condition using PSMA PET/CT. The aim of this study is to examine the incidence and clinical significance of PTI and the associated management strategies since the implementation of the PSMA PET/CT scan. This study involves a retrospective cohort study of 61 PTI cases depicted on PSMA PET/CT scans performed between January 2016 and July 2021, almost exclusively for (re)staging prostate cancer. The medical records of the included cases were retrospectively reviewed and data of the PSMA PET/CT scans, primary malignancy, thyroid diagnostics, treatment, and follow-up were collected. PTI was reported in 1.1% of the patients who underwent oncologic PSMA PET/CT scans included in this study. Two PTI cases had a histologically proven thyroid cancer: one a benign thyroid lesion and one a metastasis of a renal cell carcinoma. In none of the cases in whom any form of further thyroid workup was withheld, the PTI became clinically relevant during follow-up (median 1.8years (1.1-3.3)). Six patients (10%) died due to their primary cancer. The incidence of thyroid incidentalomas on PSMA PET/CT was low (1.1%) in this large, two-center experience. Less than half of the PTI cases were analyzed and the risk of malignancy, despite being low, was not negligible. The clinical outcome was good using a standard diagnostic workup for PTI, while the prognosis of the patient was determined by the primary malignancy. The consideration to analyze and treat PTI cases should be part of the shared decision-making in cancer patients.

Incidental uptake of fluorodeoxyglucose in the Waldeyer\u2019s ring and risk of oropharyngeal malignancy

PurposeFluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly used to diagnose and stage malignancy. The aim of this article is to investigate the significance of incidental FDG uptake in the Waldeyer’s ring and to assess its value in predicting clinically occult oropharyngeal malignancy.MethodsAll FDG-PET/CT scans performed in Imperial College NHS Foundation Trust, UK between January 2012 and November 2018 were included. Patients with known or suspected oropharyngeal malignancy or lymphoma were excluded. Minimum follow-up was 12 months.ResultsA total of 724 scans revealed oropharyngeal uptake of FDG. Of these, 102 were included in the study. Most patients (62.1%) were scanned as part of staging for other malignancies. Oropharyngeal FDG uptake was asymmetrical in 57.3% of the cases. Uptake was more common in the tonsils (56.3%), followed by the tongue base (31.1%) and both sites (12.6%). In 41.7% of reports, appearance was described as likely physiological; however, 52.4% of reports advised direct visualisation, clinical correlation or ENT opinion. Only 24.3% (25/102) of patients were referred and seen by ENT, 14.6% (15/102) of which had an interval PET scan and 8.7% (9/102) proceeded to tissue diagnosis. There was one oropharyngeal cancer identified and one unexpected metastasis from esophageal cancer.ConclusionIncidental uptake on PET/CT in the oropharynx is common. However, malignancy is rare (1.9%) and, when present, is associated with high SUVmax and asymmetrical uptake. Imaging results must be correlated clinically. These patients should be seen by an ENT specialist yet most may not require further investigations.

Incidental Detection of Ischemic Myocardium on 68Ga-FAPI PET/CT.

Recent studies using Ga-68-labeled fibroblast activation protein inhibitors (FAPI) PET have shown strong association between focal uptake of FAPI in myocardium and presence of coronary artery disease. We present an interesting case of a 76-year-old female with breast cancer with incidental uptake on FAPI PET in apex and septal wall of left ventricle myocardium correlating with findings of ischemia on dobutamine stress myocardial perfusion imaging and anatomical stenosis on coronary angiography.

Clinical relevance of incidental focal breast uptake on fluorine-18 fluorodeoxyglucose PET/computed tomography studies: an experience in a high-load center of Spain.

We aimed to determine the frequency and clinical significance of breast incidental uptake (BIU) detected through fluorine-18 fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) in a single, high-load center. In this retrospective study, we analyzed a total of 13 763 PET/CT studies performed from January 2017 to January 2020. After excluding 3148 scans, the maximum standardized uptake value (SUVmax) and maximum diameter (cm) of each BIU were measured. Clinical management, ultrasound/mammography and pathology reports were analyzed. We found BIU in 27 scans of 26 patients (0.3% of the studies). Mean age was 62.2 years and 88.5% were women; 84.6% underwent PET/CT for oncological indications. Ultrasound/mammography was consequently performed in 23 patients (88.5%), and histological correlations were available for Breast Imaging Reporting and Data System categories 4 and 5. Finally, lesions were benign in 14 patients (60.9%; two of them with low/intermediate risk of malignancy) and malignant in nine patients (39.1%). The remaining three patients had no ultrasound/mammography reports. Mean SUVmax of benign and malignant lesions were 2.6 ± 1.4 and 5.8 ± 3.5, respectively (P = 0.002). Considering a SUVmax cut-off value of 4.0, the sensitivity and specificity for differentiating benign vs. malignant lesions were 67 and 93%, respectively. Benign lesions were smaller than malignant in CT (maximum diameter:1.3 ± 0.5 cm vs. 2.0 ± 1.0 cm, P = 0.02). Although BIU detected by 18F-FDG PET/CT is infrequently found, the risk of malignancy remains very high (39.1%). Both SUVmax and maximum diameter were greater in malignant than in benign lesions. An exhaustive study with ultrasound/mammography and selective histopathological correlation is mandatory after BIU findings, even in small lesions.