Incidental PET/CT findings in the cancer patient: how should they be managed? Surgery. 2009;146:274-281. [PMID: 19628085 DOI: 10.1016/j.surg.2009.04.024]

Returning Incidental Research Findings From 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography to Participants: A Survey of Investigators From a Clinical Trial of Rheumatoid Arthritis

OBJECTIVE

There are limited data on researchers' attitudes and beliefs on returning and managing incidental research findings from whole body 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG PET/CT) imaging.

METHODS

Site principal investigators (PIs) who enrolled participants for the Treatments Against Rheumatoid Arthritis and Effect on FDG PET/CT (TARGET) trial were surveyed.

RESULTS

Of the 28 TARGET site PIs eligible for the study, 18 consented to participate (response rate: 64%). Many site PIs returned incidental findings to participants (61%), and the most common finding that was returned was serious (but not life-threatening) and treatable (54.5%). More than half of the investigators believed that adequacy of clinical follow up (58.8%) and legal liability if incidental findings are not disclosed (55.6%) were extremely important factors in returning incidental research findings from whole body FDG PET/CT. All investigators felt very obligated to return incidental research findings if scans revealed a treatable, high-risk medical condition. Most investigators felt very obligated to disclose incidental findings with important health implications (94.4%), for which proven preventive or therapeutic interventions exist (77.8%), that provide early detection of a health problem (72.2%), if participants ask for their incidental findings (72.2%), and if scans have established validity for a particular medical condition (61.1%).

CONCLUSION

Although it is recommended that researchers report and manage incidental research findings, our data show differing views and uncertainties on what and how to return, and the extent of follow up needed to manage, incidental findings from whole body FDG PET/CT; this highlights the need for more specific and standardized guidance.

Cancer in Patients With Incidental Asymmetric Oropharynx Positron Emission Tomography Uptake

Importance

Asymmetric oropharynx uptake on positron emission tomography (PET)/computed tomography (CT) is a common incidental finding and often prompts otolaryngology referral to rule out malignancy; however, the true risk of malignancy based on this finding is unknown.

Objective

To identify the incidence of oropharynx cancer in patients with incidental asymmetric oropharynx PET uptake.

Design, Setting, and Participants

In this retrospective cohort study, patients 18 years and older undergoing PET/CT scans at Mayo Clinic between January 2001 and December 2018 were included. Patients with a history or pretest suspicion of oropharynx cancer were excluded. Data were analyzed from March 2021 to December 2023.

Exposure

Blinded radiologic review of imaging studies, including measurement of maximum standardized uptake values (SUVmax) of the ipsilateral side of concern and contralateral side. Retrospective medical record review for associated clinical data.

Main Outcomes and Measures

The primary study outcome was the incidence of oropharynx cancer diagnosis in patients with asymmetric oropharynx PET uptake. The primary outcome was formulated before data collection.

Results

Of the 1854 patients identified with asymmetric oropharynx PET uptake, 327 (17.6%) met inclusion criteria. Of these, 173 (52.9%) were male, and the median (range) age was 65.0 (24.8-90.7) years. The mean (SD) follow-up interval was 52.1 (43.4) months. A total of 18 of 327 patients (5.5%) were newly diagnosed with oropharynx cancer. The most common diagnosis was squamous cell carcinoma (n = 9), followed by lymphoma (n = 8), and sarcoma (n = 1). Patients with an incidental diagnosis of oropharynx cancer had higher mean (SD) ipsilateral SUVmax (8.7 [3.7] vs 5.3 [1.9]) and SUVmax ratio (3.0 [1.6] vs 1.6 [0.6]) compared with patients with normal examination findings. SUVmax ratio and difference were found to be good discriminators of oropharynx cancer, with areas under the receiver operating characteristic curve of 86.3% (95% CI, 76.4-94.6) and 85.8% (95% CI, 74.8-94.6), respectively. Patients with a new diagnosis of oropharynx cancer were more likely to have a corresponding CT abnormality than those with normal examination findings (6 of 18 [33%] vs 24 of 295 [8.1%]). Patients with concerning lesions on oropharynx palpation by an otolaryngology health care professional were significantly more likely to be diagnosed with oropharynx cancer compared with patients with normal examination findings (odds ratio, 28.4; 95% CI, 6.6-145.8).

Conclusions and Relevance

In this cohort study, while incidental asymmetric oropharynx PET uptake was common, a new diagnosis of oropharynx cancer was not and potentially results in a large volume of unnecessary referrals and work-up. Using SUVmax ratio, SUVmax difference, and CT correlation may increase the benefit of referral. Patients with a palpable oropharynx lesion and asymmetric oropharynx PET uptake should undergo confirmatory biopsy.

Clinical implications of non-breast cancer related findings on FDG-PET/CT scan prior to neoadjuvant chemotherapy in patients with breast cancer

PURPOSE

Breast cancer (BC) patients undergoing FDG-PET/CT scans for neoadjuvant chemotherapy (NAC) may have additional non-BC related findings. The aim of this study is to describe the clinical implications of these findings.

METHODS

We included BC patients who underwent an FDG-PET/CT scan in our institute between 2011-2020 prior to NAC. We focused on patients with an additional non-BC related finding (i.e. BC metastases were excluded) for which diagnostic work-up was performed. Information about the diagnostic work-up and the clinical consequences was retrospectively gathered. A revision of all FDG-PET/CT scans was conducted by an independent physician to assess the suspicion level of the additional findings.

RESULTS

Of the 1337 patients who underwent FDG-PET/CT, 202 patients (15%) had an non-BC related additional finding for which diagnostic work-up was conducted, resulting in 318 examinations during the first year. The non-BC related findings were mostly detected in the endocrine region (26%), gastro-intestinal region (16%), or the lungs (15%). Seventeen patients (17/202: 8%, 17/1337: 1.3%) had a second primary malignancy. Only 8 patients (8/202: 4%, 8/1337: 0.6%) had a finding that was considered more prognosis-determining than their BC disease. When revising all FDG-PET/CT scans, 57 (202/57: 28%) of the patients had an additional finding categorized as low suspicious, suggesting no indication for diagnostic work-up.

CONCLUSION

FDG-PET/CT scans used for dissemination imaging in BC patients detect a high number of non-BC related additional findings, often clinically irrelevant and causing a large amount of unnecessary work-up. However, in 8% of the patients undergoing diagnostic work-up for an additional finding, a second primary malignancy was detected, warranting diagnostic attention in selected patients.

False Liver Metastasis by Positron Emission Tomography/Computed Tomography Scan after Chemoradiotherapy for Esophageal Cancer-Potential Overstaged Pitfalls of Treatment

In patients with esophageal cancer undergoing neoadjuvant chemoradiotherapy (nCRT), subsequent restaging with F-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) can reveal the presence of interval metastases, such as liver metastases, in approximately 10% of cases. Nevertheless, it is not uncommon in clinical practice to observe focal FDG uptake in the liver that is not associated with liver metastases but rather with radiation-induced liver injury (RILI), which can result in the overstaging of the disease. Liver radiation damage is also a concern during distal esophageal cancer radiotherapy due to its proximity to the left liver lobe, typically included in the radiation field. Post-CRT, if FDG activity appears in the left or caudate liver lobes, a thorough investigation is needed to confirm or rule out distant metastases. The increased FDG uptake in liver lobes post-CRT often presents a diagnostic dilemma. Distinguishing between radiation-induced liver disease and metastasis is vital for appropriate patient management, necessitating a combination of imaging techniques and an understanding of the factors influencing the radiation response. Diagnosis involves identifying new foci of hepatic FDG avidity on PET/CT scans. Geographic regions of hypoattenuation on CT and well-demarcated regions with specific enhancement patterns on contrast-enhanced CT scans and MRI are characteristic of radiation-induced liver disease (RILD). Lack of mass effect on all three modalities (CT, MRI, PET) indicates RILD. Resolution of abnormalities on subsequent examinations also helps in diagnosing RILD. Moreover, it can also help to rule out occult metastases, thereby excluding those patients from further surgery who will not benefit from esophagectomy with curative intent.

Parotid gland incidentalomas: A single-institution experience

PURPOSE

Parotid gland incidentaloma (PGI) management has not been well characterized in the literature. This study assesses clinicopathologic features, initial evaluation, management, and outcomes of PGIs discovered on various imaging modalities.

MATERIALS AND METHODS

This is a retrospective case series from a single academic institution. The study cohort included 34 patients with parotid gland incidentalomas discovered between January 2009 and December 2019.

RESULTS

Parotid gland incidentalomas were most frequently identified on magnetic resonance imaging (16 patients, 47.1%). Most patients (26 patients, 76.5%) underwent further evaluation with subsequent imaging, most often magnetic resonance imaging (18 patients, 69.2%), and fine needle aspiration biopsy (33 patients, 97.1%). Most tumors were benign on fine needle aspiration biopsy (19 patients, 57.6%). Most cases (21 patients, 61.8%) were managed with observation without parotidectomy. Malignant findings on fine needle aspiration cytology were associated with increased likelihood of undergoing parotidectomy (25% vs 0%; p = 0.04). Among the patients who received a parotidectomy, most (8 patients, 61.5%) had benign findings on final histopathology.

CONCLUSION

Parotid gland incidentalomas were discovered across a diverse set of imaging modalities in our institution. Magnetic resonance imaging and fine needle aspiration were often performed for further evaluation. Most cases were found to be benign on fine needle aspiration and were managed with observation. These findings highlight the necessity of appropriate work-up for these tumors, and the need for shared decision making between the patient and the physician in selecting the appropriate treatment strategy.

Clinically significant findings in patients with focal incidental colorectal abnormalities on positron emission tomography-CT scans

INTRODUCTION

The aim of this study was to determine the clinical significance of focal incidentally detected colorectal abnormalities on ¹⁸ F- Fluoro-2-Deoxy-D-Glucose (FDG) PET-CT scans.

METHODS

Retrospective audit of PET-CT scans performed at our institution between 2009 and 2014. Demographic and clinical details were retrieved from electronic patient records. An advanced adenoma was defined as: ≥1 cm in size, tubullo-villous histology, or displaying high grade dysplasia. A high-risk lesion (HRL) was defined as an advanced adenoma or colorectal cancer (CRC).

RESULTS

Of the 1911 PET-CT eligible scans, focal incidental colorectal FDG uptake was detected in 99 (5.2%) patients. Colonoscopy was undertaken in 43 (43.4%) patients and 45 FDG-avid sites were evaluated. The commonest site of abnormal FDG uptake was the rectosigmoid region, with 34 (75.6%) of the 45 foci being located in this area. Overall, 23 (53.5%) of these patients had clinically significant pathology. Of the 45 focal PET-CT abnormalities evaluated, 17 (37.8%) were adenomas, of which 11 (24.4%) were advanced adenomas, and six (13.3%) were cancers, with a total of 17 (37.8%) HRLs. Five of the six patients with CRC underwent surgical resection, whilst one had endoscopic resection. The overall survival for the entire cohort was 18 months (range 1-72 months) with those that underwent colonoscopy having higher overall survival compared to those that did not (38 vs. 13.5 months).

CONCLUSION

Incidental colorectal abnormalities on PET-CT scans are often clinically significant. However, careful selection for colonoscopy is important due to the poor survival in these patients related to the underlying primary malignancy.

FDG PET/CT to Detect Incidental Findings in Patients With Hepatocellular Carcinoma-Additional Benefit for Patients Considered for Liver Transplantation?

PURPOSE

FDG PET/CT has been described for noninvasive grading, detection of extrahepatic spread, and recurrence in hepatocellular carcinoma (HCC). As compared with localized imaging approaches (MRI, ultrasonography), FDG PET/CT not only focuses on the liver, but covers a long field of view from the base of the skull to the thighs, visualizing pathologic findings not related to HCC. The aims of this retrospective study were to (1) describe the frequency of relevant incidental findings on FDG PET/CT in HCC patients, (2) evaluate the impact on treatment strategy in HCC patients considered for liver transplantation, and (3) to discuss the role of FDG PET/CT in patients considered for transplantation in general.

METHODS

Four hundred thirty-nine FDG PET/CT examinations of 345 HCC patients were screened for incidental findings. The clinical information system was searched for examinations performed after FDG PET/CT and aimed at verification of incidental findings. Of 345 HCC patients, 81 patients were considered for liver transplantation. The impact of incidental findings was recorded separately for this subgroup.

RESULTS

One hundred one patients with incidental findings in 439 FDG PET/CT examinations were identified. The incidental findings comprised 22 neoplasms (9 malignant) and 52 inflammations. Liver transplantation was not performed because of an incidental finding on FDG PET/CT in 9 (11.1%) of 81 patients.

CONCLUSIONS

FDG PET/CT is capable of identifying relevant incidental findings (ie, secondary malignancy, benign tumors, and inflammation) in HCC patients and HCC patients considered for liver transplantation and thus influencing HCC patient management. FDG PET/CT might also be beneficial in patients considered for transplantation of different organs.

The clinical application of 18F-FDG PET/CT in pancreatic cancer: a narrative review

Pancreatic cancer is one of the worst prognoses of all malignant tumors, with an annual incidence near its annual mortality rate. To improve the prognosis of patients with pancreatic cancer, it is essential to diagnose and evaluate pancreatic cancer early. Imaging examinations play an essential role in tumor detection, staging, and surgical resection assessment and can provide reliable evidence for the diagnosis and treatment of pancreatic cancer. Currently, imaging techniques commonly used for pancreatic cancer include endoscopic ultrasound (EUS), conventional ultrasound, magnetic resonance imaging (MRI), multidetector spiral computed tomography (MDCT), positron emission tomography/computed tomography (PET/CT), and others PET/CT is a new imaging device composed of PET and CT. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) is a commonly used tracer in the clinic. Cancer cells are more robust than other ordinary cells in that they can ingest glucose, and the structure of glucose is similar to the structure of ¹⁸F-FDG. Therefore, after the injection of ¹⁸F-FDG, ¹⁸F-FDG in tumor cells appears very thick during PET scanning. Therefore, PET/CT can determine the metabolic capacity and anatomical position of pancreatic tumor cells in the body accurately diagnose the patient's condition and tumor location. It plays a vital role in early diagnosis and accurate staging, predicts survival, and monitors therapeutic effectiveness and pancreatic cancer recurrence. Although ¹⁸F-FDG PET/CT has limitations in identifying inflammatory diseases and tumors, it still has good development potential. This article reviews the clinical application of ¹⁸F-FDG PET/CT in pancreatic cancer.

FDG-PET/CT identified distant metastases and synchronous cancer in squamous cell carcinoma of the head and neck: the impact of smoking and P16-s

PURPOSE

Whole-body FDG-PET-CT is widely used at diagnosis of squamous cell carcinoma of the head and neck (SCCHN) but may identify suspicious lesions outside the neck that require investigation. This study evaluated the impact of smoking and P16-status on the incidence of malignant disease outside the head and neck region in newly diagnosed patients with SCCHN.

METHODS

All PET-positive foci outside the head-neck area were registered in 1069 patients planned for postoperative or curative intent radiotherapy with whole-body FDG-PET/CT from 2006 to 2012. All patient files were retrospectively investigated and clinical parameters, tobacco use, HPV (P16)-status and subsequent malignant disease registered.

RESULTS

Malignancy outside the neck was diagnosed in 9% of smokers, 2% of never-smokers, and 5% of patients with P16-positive oropharyngeal squamous cell carcinoma (OPSCC). Clinically suspicious PET-positive foci outside the head-neck were malignant in 55% of smokers, 34% of never-smokers, and in 38% of P16-pos OPSCC. All but two patients with cancer occurring outside the head and neck region were smokers.

CONCLUSION

Malignancy outside the neck at diagnosis was more frequent in smokers compared to non-smokers or P16-pos OPSCC. A high proportion of clinically suspicious PET-positive foci were non-malignant.

Screening for second malignancies in mycosis fungoides: non-Hodgkin lymphoma, Hodgkin lymphoma, lung cancer, bladder cancer and melanoma

BACKGROUND

Patients with mycosis fungoides (MF) are at increased risk of developing non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL), lung cancer, bladder cancer and melanoma. The characteristics of patients developing these malignancies have not been specifically delineated. In addition, there are no established guidelines for screening MF patients for second malignancies.

MATERIALS/METHODS

We identified 742 patients with MF who developed second malignancies in the Surveillance Epidemiology and End Result-18 database.

RESULTS

The majority of second malignancy patients were white and male, mean age 55-67 years at diagnosis of MF, and mean age 61-72 years at diagnosis of second malignancy. The majority of patients diagnosed with second malignancies had early stage MF. MF patients with NHL, lung cancer, and bladder cancer tended to be diagnosed at earlier stages of the second malignancy than patients without MF and demonstrated better 5-year overall survival. There was no improvement in stage at diagnosis or survival for MF patients who were diagnosed with melanoma compared to patients without MF.

CONCLUSIONS

Improvements in survival in MF/NHL, MF/lung cancer and MF/bladder cancer patients may reflect differences in disease biology secondary to having MF or the importance of increased contact with the healthcare system. MF/melanoma data suggest that patients require regular pigmented-lesion-focused skin examinations. Tools for screening include regular lymph node examinations, pigmented-lesion-focused examinations and detailed review of systems questions. Smoking cessation counseling is key intervention in this population, as is ensuring that all age- and sex-specific cancer screenings are up-to-date (e.g. lung cancer screening, mammography, and colonoscopy). The utility of regular imaging for second malignancy screening and lab testing such as routine urinalysis requires additional study and expert consensus.

Incidence, Impact, and Management of Incidentalomas on Preoperative Computed Tomographic Angiograms for Breast Cancer Patients with and without Genetic Mutations

BACKGROUND

Preoperative abdominal computed tomographic angiograms for free flap breast reconstruction improve operative safety and efficiency, but incidental findings are common and potentially affect management. In addition, the authors hypothesized that patients with genetic mutations might have a higher rate of significant findings. The authors present the largest series of computed tomographic angiogram "incidentalomas" in these two populations and an evidence-based algorithm for managing common findings.

METHODS

All patients undergoing free flap breast reconstruction at Northwell Health between 2009 and 2017 were eligible. Medical history, perioperative details, and radiology reports were examined with abnormal findings recorded. Published literature was reviewed with radiologists to develop standardized guidelines for incidentaloma management.

RESULTS

Of 805 patients included, 733 patients had abdominal imaging. One hundred ninety-five (27 percent) had a completely negative examination. In the remaining 538 patients, benign hepatic (22 percent) and renal (17 percent) findings were most common. Sixteen patients (2.2 percent) required additional imaging (n = 15) or procedures (n = 5). One finding was concerning for malignancy-renal cell carcinoma-which interventional radiology ablated postoperatively. Seventy-nine patients (10.8 percent) had a genetic mutation but were not found to have a statistically significant higher rate of incidentalomas.

CONCLUSIONS

The authors' rate of computed tomographic angiography incidental findings (73 percent) is consistent with previous studies, but the rate requiring further intervention (2.2 percent) is lower. Incidental findings were no more common or pathologic among genetic mutation carriers. The authors also introduce an evidence-based algorithm for the management of common incidentalomas. Using these guidelines, plastic surgeons can reassure patients, regardless of mutation status, that incidentalomas are most commonly benign and have minimal impact on their surgical plan.

Focal Thyroid Incidentalomas on 18F-FDG PET/CT: A Systematic Review and Meta-Analysis on Prevalence, Risk of Malignancy and Inconclusive Fine Needle Aspiration

BACKGROUND

The rising demand for ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography (¹⁸F-FDG PET/CT) has led to an increase of thyroid incidentalomas. Current guidelines are restricted in giving options to tailor diagnostics and to suit the individual patient.

OBJECTIVES

We aimed at exploring the extent of potential overdiagnostics by performing a systematic review and meta-analysis of the literature on the prevalence, the risk of malignancy (ROM) and the risk of inconclusive FNAC (ROIF) of focal thyroid incidentalomas (FTI) on ¹⁸F-FDG PET/CT.

DATA SOURCES

A literature search in MEDLINE, Embase and Web of Science was performed to identify relevant studies.

STUDY SELECTION

Studies providing information on the prevalence and/or ROM of FTI on ¹⁸F-FDG PET/CT in patients with no prior history of thyroid disease were selected by two authors independently. Sixty-one studies met the inclusion criteria.

DATA ANALYSIS

A random effects meta-analysis on prevalence, ROM and ROIF with 95% confidence intervals (CIs) was performed. Heterogeneity and publication bias were tested. Risk of bias was assessed using the quality assessment of diagnostic accuracy studies (QUADAS-2) tool.

DATA SYNTHESIS

Fifty studies were suitable for prevalence analysis. In total, 12,943 FTI were identified in 640,616 patients. The pooled prevalence was 2.22% (95% CI = 1.90% - 2.54%, I² = 99%). 5151 FTI had cyto- or histopathology results available. The pooled ROM was 30.8% (95% CI = 28.1% - 33.4%, I² = 57%). 1308 (83%) of malignant nodules were papillary thyroid carcinoma (PTC). The pooled ROIF was 20.8% (95% CI = 13.7% - 27.9%, I² = 92%).

LIMITATIONS

The main limitations were the low to moderate methodological quality of the studies and the moderate to high heterogeneity of the results.

CONCLUSION

FTI are a common finding on ¹⁸F-FDG PET/CTs. Nodules are malignant in approximately one third of the cases, with the majority being PTC. Cytology results are non-diagnostic or indeterminate in one fifth of FNACs. These findings reveal the potential risk of overdiagnostics of FTI and emphasize that the workup of FTI should be performed within the context of the patient's disease and that guidelines should adopt this patient tailored approach.

Clinical impact of pre-treatment FDG-PET/CT staging of primary ovarian, fallopian tube, and peritoneal cancers in women

INTRODUCTION

To assess the clinical impact of preoperative fludeoxyglucose (FDG) with positron emission tomography (PET) and computed tomography (CT) in women with ovarian, fallopian tube, or peritoneal cancer with focus on consequences of added findings (AFs).

MATERIAL AND METHODS

FDG-PET/CT was implemented as a standard imaging modality for women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer at our institution in 2008. After full implementation, all preoperative scans were reviewed and AFs were evaluated from January 2011 to December 2012. Decisions regarding further examination made at the first multidisciplinary team conference were recorded. Subsequent procedures were tracked via medical records, and the impact of AFs on additional examinations, delay, and change in treatment plans was evaluated.

RESULTS

Forty-four (21.1%) of 209 women presented with AFs. Further examination was performed in 35/44 (79.5%). Malignancy was identified in 15/35 (42.9%), revealing metastases from ovarian, fallopian tube, or peritoneal cancer in 11, a synchronous primary cancer in 3, and recurrence of a previous cancer in 1 woman. The ovarian, fallopian tube, or peritoneal cancer metastases were localized in the lungs, uterus, colon, vagina, and breasts. The remaining 20 AFs revealed 2 benign lesions and 1 pre-malignant lesion, whereas no abnormality was found in 17. Further examination of AFs resulted in a significant time delay until treatment start of median 4 days (range 1-83 days, P < 0.004).

CONCLUSIONS

Further examinations of AFs by FDG-PET/CT delayed time to start of treatment by median 4 days in women with newly diagnosed ovarian, fallopian tube, or peritoneal cancer in a contemporary institution with fast-track access to additional diagnostics. The clinical implications of this must be balanced against the gain of detecting unrecognized malignancy in 15 of 209 women (7.2%).

Two decades of SPECT/CT - the coming of age of a technology: An updated review of literature evidence

PURPOSE

Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) was introduced as a hybrid SPECT/CT imaging modality two decades ago. The main advantage of SPECT/CT is the increased specificity achieved through a more precise localization and characterization of functional findings. The improved diagnostic accuracy is also associated with greater diagnostic confidence and better inter-specialty communication.

METHODS

This review presents a critical assessment of the relevant literature published so far on the role of SPECT/CT in a variety of clinical conditions. It also includes an update on the established evidence demonstrating both the advantages and limitations of this modality.

CONCLUSIONS

For the majority of applications, SPECT/CT should be a routine imaging technique, fully integrated into the clinical decision-making process, including oncology, endocrinology, orthopaedics, paediatrics, and cardiology. Large-scale prospective studies are lacking, however, on the use of SPECT/CT in certain clinical domains such as neurology and lung disorders. The review also presents data on the complementary role of SPECT/CT with other imaging modalities and a comparative analysis, where available.

Positron emission tomography/computed tomography imaging appearance of benign and classic “do not touch” osseous lesions

BACKGROUND

Classic “do not touch” and benign osseous lesions are sometimes detected on ¹⁸-F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) studies. These lesions are often referred for biopsy because the physician interpreting the PET/CT may not be familiar with the spectrum of ¹⁸F-FDG uptake patterns that these lesions display.

AIM

To show that “do not touch” and benign osseous lesions can have increased ¹⁸F-FDG uptake above blood-pool on PET/CT; therefore, the CT appearance of these lesions should dictate management rather than the standardized uptake values (SUV).

METHODS

This retrospective study evaluated 287 independent patients with 287 classic “do not touch” (benign cystic lesions, insufficiency fractures, bone islands, bone infarcts) or benign osseous lesions (hemangiomas, enchondromas, osteochondromas, fibrous dysplasia, Paget’s disease, osteomyelitis) who underwent ¹⁸F-FDG positron emission tomography/computed tomography (PET/CT) at a tertiary academic healthcare institution between 01/01/2006 and 12/1/2018. The maximum and mean SUV, and the ratio of the maximum SUV to mean blood pool were calculated. Pearson’s correlations between lesion size and maximum SUV were calculated.

RESULTS

The ranges of the maximum SUV were as follows: For hemangiomas (0.95-2.99), bone infarcts (0.37-3.44), bone islands (0.26-3.29), enchondromas (0.46-2.69), fibrous dysplasia (0.78-18.63), osteochondromas (1.11-2.56), Paget’s disease of bone (0.93-5.65), insufficiency fractures (1.06-12.97) and for osteomyelitis (2.57-12.64). The range of the maximum SUV was lowest for osteochondromas (maximum SUV 2.56) and was highest for fibrous dysplasia (maximum SUV of 18.63). There was at least one lesion that demonstrated greater ¹⁸F-FDG avidity than the blood pool amongst each lesion type, with the highest maximum SUV ranging from 9.34 times blood pool mean (osteomyelitis) to 1.42 times blood pool mean (hemangiomas). There was no correlation between the maximum SUV and the lesion size except for enchondromas. Larger enchondromas had higher maximum SUV (r = 0.36, P = 0.02).

CONCLUSION

The classic “do not touch” lesions and classic benign lesions can be ¹⁸F-FDG avid. The CT appearance of these lesions should dictate clinical management rather than the maximum SUV.

Incidental findings on 18-FDG PET-CT in head and neck cancer. A retrospective case-control study of incidental findings on 18-FDG PET-CT in patients with head and neck cancer

PURPOSE

Use of 18-FDG PET-CT is increasing in patients with head and neck cancer, enabling the identification of metastases or synchronous malignancies, but also 'incidental' disease. We aimed to establish the rate of 'incidental' findings resulting from 18-FDG PET-specific imaging, that would not have been otherwise identified on other imaging, in patients with head and neck cancer undergoing staging or surveillance of disease.

METHODS

18-FDG PET-CT was performed for investigation or surveillance. Case notes were reviewed retrospectively. Unexpected findings identifiable on CT imaging alone, or by FDG-PET were recorded. For those only identifiable with FDG-PET, findings were divided into either 'incidental' or 'intentional', and benign or malignant.

RESULTS

93 patients underwent 18- FDG PET-CT. 86.0% had new pathology identified. 3.2% had a new malignancy identified. 37.6% had new findings on FDG-PET that would not have been identified on CT alone: 5.4% had 'intentional findings' (metastasis), and 32.3% had 'incidental findings' (synchronous malignancy or benign). 1.1% had a new malignancy on FDG-PET alone.

CONCLUSIONS

Intentional and incidental findings are likely on 18-FDG PET-CT. Whilst important for patient management, there is an associated emotional and financial cost, which needs acknowledgement and further investigation.

Clinical-endoscopic relevance of incidental colorectal lesions detected by PET-CT

AIM

to determine the proportion of incidental colon lesions detected by PET-CT and their correlation with the endoscopic and histological findings. In addition, to determine the maximum standardized uptake value (SUVmax) that can discriminate between benign and malignant lesions in our series of cases.

METHODS

this was a retrospective study of 3,000 patients evaluated by PET-CT for staging or response to treatment of primary neoplasms, between 2011 and 2015. Patients with incidental uptake in the colon were included in the study. Exclusion criteria included an incomplete, poorly prepared or abandoned colonoscopy, inflammatory bowel disease and treatment with metformin.

RESULTS

the study cohort comprised 71 patients evaluated by PET-CT and subsequently analyzed by endoscopy; 69% were male with a mean age of 65.77 ± 11.2. The rate of incidental colon lesions found by PET-CT was 1.73%, with 52 incidental colonic uptakes reported in 50 patients. The location of the uptake was the rectum (19.23%), sigmoid colon (34.62%), descending colon (13.46%), transverse colon (1.9%), ascending colon (19.23%), cecum (9.62%) and ileocolic anastomosis (1.92%). Thirty-five pathological colonoscopies (71.15%) were identified: the findings included five neoplasms (13.51%), two inflammatory lesions (5.4%) and 30 adenomatous polyps (81.1%). Significant differences were found between neoplastic SUVmax (11.7 g/ml; p = 0.03) and polyps (9.26 g/ml; p = 0.04) in relation to inflammatory lesions and normal endoscopies (6.05 g/ml). There were no differences in terms of the size of the polyps, nor the presence or absence of high grade dysplasia (p = 0.12 and 0.33). Both PET-CT and endoscopy proved consistent for locating lesions (k 0.90; CI 95% 0.86-0.93).

CONCLUSION

there is a good correlation between the findings identified by PET-CT and the endoscopic study. In our study, a SUVmax > 11 g/ml suggests a malignant pathology, which aids the prioritization of an endoscopic study.

Incidence and Economic Impact of Incidental Findings on 18F-FDG PET/CT Imaging

PURPOSE

The study sought to determine the incidence of incidental findings on whole-body positron emission tomography with computed tomography (PET/CT) imaging and the average costs of investigations to follow-up or further characterize incidental findings.

METHODS

Imaging reports of 215 patients who underwent whole-body PET/CT imaging were retrospectively reviewed. Our provincial picture archiving and communication system was queried and patient charts were reviewed to identify all investigations performed to follow-up incidental findings within 1 year of the initial PET/CT study. Costs of follow-up imaging studies (professional and technical components) and other diagnostic tests and procedures were determined in Canadian dollars (CAD) and U.S. dollars (USD) using the 2015 Ontario Health Insurance Plan Schedule of Benefits and Fees and 2016 U.S. Medicare Physician Fee Schedule, respectively.

RESULTS

At least 1 incidental finding was reported in 161 reports (74.9%). The mean number of incidental findings ranged from 0.64 in patients <45 years of age to 2.2 in patients 75 years of age and older. Seventy-five recommendations for additional investigations were made for 64 (30%) patients undergoing PET/CT imaging, and 14 of those were carried out specifically to follow-up incidental findings. Averaged across all 215 patients, the total cost of investigations recommended to follow-up incidental findings was CAD$105.51 (USD$127.56) per PET/CT study if all recommendations were acted on, and CAD$22.77 (USD$29.14) based on investigations actually performed.

CONCLUSIONS

As the incidence of incidental findings increases with age and a larger proportion of elderly patients is expected as population demographics change, it will be increasingly important to consider incidental findings on PET/CT imaging with standardized approaches to follow-up.

PET Scan Contribution in Chest Tumor Management: A Systematic Review for Thoracic Surgeons

Aims and background

In the 90s, the introduction of positron emission tomography (PET) represented a milestone in the staging of thoracic tumors. In the last 10 years, PET scan has been widely adopted in thoracic oncology, showing high accuracy in diagnosis and staging and with promising issues in defining prognosis. The aim of this systematic review was to focus on the results and pitfalls of PET scan use in the modern management of chest tumors.

Methods and study design.

The literature search was performed on May 2010 in PubMed, Embase, and Cochrane according to PRISMA protocol. The search was restricted to publications in English, using in the same string the word “PET” with 9 different chest tumors; results were then filtered by eliminating technical articles, focusing only on papers in which surgery was considered as a potential diagnostic or therapeutic tool. From 6600 papers initially selected, 99 manuscripts were fully analyzed.

Results

Glucose uptake is a metabolic marker useful in the diagnosis and staging of chest tumors. In lung cancer screening, standard uptake value is helpful in defining the risk of malignancy of isolated pulmonary nodules. The addition of PET scan to conventional staging increases detection of nodal and distant metastases in lung cancer, esophageal cancer and malignant mesothelioma. In thymoma, a close relationship between standard uptake value, histology, and Masaoka stage has been advocated. This link between glucose uptake and prognosis suggests that PET translates biological tumor behavior into clinically detectable findings.

Conclusions

PET scan has a crucial role in thoracic oncology due to its impact on diagnosis, staging and prognosis. PET scan expresses the biological behavior of tumors, opening interesting perspectives in chest tumor management and improving detection and stage grouping in lung cancer. It anticipates the diagnosis in long-incubating diseases such as mesothelioma and increases biological knowledge of rare diseases, such as thymoma and other mediastinal tumors.

Incidental Findings on FDG PET/CT in Head and Neck Cancer

Objective

18F-fluoro-deoxy-glucose positron emission tomography/computed tomography (FDG PET/CT) imaging is common in head and neck cancer and often identifies incidental findings that necessitate additional patient evaluations. Our goal was to assess the frequency and nature of these incidental imaging findings on FDG-PET/CT.

Study Design

Retrospective cohort study.

Setting

Tertiary medical center.

Subjects and Methods

All patients with head and neck cancer who had undergone FDG-PET/CT imaging between January 2014 and June 2015 at our institution were evaluated for incidental findings.

Results

A total of 293 patients met criteria; more than one-third (n = 103) had at least 1 finding unrelated to their head and neck cancer, for a total of 134 incidental findings. Incidental findings within the head and neck (33.5% of all) excluding the thyroid were most common: 35% incidental findings were concerning for malignancy; of these, 25.5% were malignant with further workup. Recommendations were given by the head and neck radiologist on 72 (53.7%) findings: 74.5% of potentially malignant findings and 42.5% of benign findings had recommendations for follow-up. Significantly more patients with findings described as malignant were given recommendations for follow-up ( P = .0004).

Conclusion

Incidental findings on FDG-PET/CT are present in more than one-third of patients with head and neck cancer. More than one-third of incidental findings were concerning for malignancy. This study illustrates how the incidental findings discovered on FDG PET/CT frequently necessitate additional evaluations unrelated to the index head and neck cancer. The impact of these additional assessments on the cost and quality of health care warrants future evaluation.

Incidental detection of colorectal lesions by FDG PET/CT scans in melanoma patients

BACKGROUND

Increased use of PET/CT scans in oncology patients has raised detection of Colorectal incidentalomas (CIs). The frequency and diagnostic outcomes of identifying these lesions in melanoma patients have not previously been studied. This studies primary objective was to determine the prevalence of CIs found on PET/CT scans in melanoma patients. The secondary objectives were to correlate the PET/CT findings with the pathology found at colonoscopy, and identify which patients were referred for colonoscopy.

METHODS

A retrospective analysis of patients identified from the prospectively collected research database of Melanoma Institute Australia. 2509 patients with melanoma underwent PET/CT scans between 2001 and 2013. The prevalence of CIs, the correlation of lesions, and the survival of patients who underwent colonoscopy versus patients who did not were analyzed.

RESULTS

The prevalence of CIs in melanoma patients who had PET/CT scans was 3.2%. Forty-five of the 81 (56%) patients with CIs underwent colonoscopy. Of these, premalignant or malignant disease was found in 58%. Patients with previous metastatic melanoma were significantly less likely to be referred for colonoscopy. Patients undergoing colonoscopy had significantly better survival, as did those without previous distant metastases before the CIs were found, and those without any metastases at the time the CIs were found. These factors were not significant on multivariate analysis.

CONCLUSION

The prevalence of incidental colorectal lesions identified on PET/CT scans in melanoma patients was found to be equivalent to that in the general cancer population. Patients undergoing colonoscopy had better survival than those who did not.

Incidental colorectal focal 18 F-FDG uptake: a novel indication for colonoscopy

BACKGROUND AND STUDY AIMS

 The relevance of incidental colorectal focal ¹⁸ F-FDG PET/CT uptake is debatable. All patients who were referred for colonoscopy because of incidental colonic focal FDG uptake were included in this retrospective study.

PATIENTS AND METHODS

 PET/CT imaging characteristics were reviewed by a nuclear physician who was blinded to endoscopic and histopathological findings to determine the location of FDG uptake sites and to measure the maximum standardized uptake values (SUVmax) and metabolic volume (MV). Endoscopic findings were categorized as malignant lesions (ML), high-risk polyps (HRP), low-risk polyps (LRP) or other non-neoplastic lesions (NNL).

RESULTS

 Seventy patients with 84 foci of FDG uptake were included. The proportions of true-positive (lesions found at colonoscopy at the same location) and false-positive (no lesion at colonoscopy) PET/CT findings were 65.5 % (n = 55) and 34.5 % (n = 29). Median SUVmax values did not differ between true-positive and false-positive findings ( P  = 0.27). Median MV30 values differed significantly between true-positive (5.5 cm ³ , [3.3 - 10.9 cm ³ ]) and false-positive (9.7 cm ³ , [5.2 - 40.8 cm ³ ]) findings ( P  = 0.015). Among the 55 true-positive FDG uptake sites, there were 14 (25.5 %) malignant lesions, 30 (54.5 %) HRP, 4 (7.3 %) LRP, and 7 (12.7 %) NNL. Median MV30 values differed significantly between advanced neoplasia (5.0 cm ³ , [2.9 - 9.7 cm ³ ]) and other endoscopic findings (9.4 cm ³ , [5.2 - 39.8 cm ³ ]) ( P  = 0.001); the AUROC was 0.71. By per-colonic segment analysis, the distribution of true-positive, false-negative, false-positive, and true-negative FDG PET/CT findings was as follows: 21.5 %, 14.2 %, 11.5 %, and 52.8 %, respectively.

CONCLUSION

 Our study demonstrates that follow-up complete colonoscopy is mandatory in all patients with incidental colorectal focal ¹⁸ F-FDG PET/CT uptake.

Detection of distant metastases in patients with locally advanced breast cancer: role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and conventional imaging with computed tomography scans

OBJECTIVE

To evaluate positron emission tomography/computed tomography (PET/CT) and conventional imaging tests for the detection of distant metastases in patients with locally advanced breast cancer.

MATERIALS AND METHODS

We included 81 patients with breast cancer who had undergone ¹⁸F-fluorodeoxyglucose (FDG) PET/CT before treatment. Conventional imaging included the following: bone scintigraphy; chest X-ray (in 14.5%) or CT (in 85.5%); and abdominal ultrasound (in 10.8%), CT (in 87.8%), or magnetic resonance imaging (in 1.4%). Histopathology and clinical/imaging follow-up served as reference.

RESULTS

Distant metastases were observed in nine patients (11.1%). On patient-based analysis, conventional imaging identified distant metastases in all 9 patients. In one patient, the initial ¹⁸F-FDG PET/CT failed to demonstrate bone metastases that was evident on bone scintigraphy. In two patients, the CT scan failed to show extra-axillary lymph node metastases that were identified on ¹⁸F-FDG PET/CT. There was no significant difference between ¹⁸F-FDG PET/CT and conventional imaging in terms of their sensitivity for the detection of distant metastases in patients with locally advanced breast cancer.

CONCLUSION

This study showed that ¹⁸F-FDG PET/CT and conventional imaging with CT scans had similar sensitivity for the diagnosis of distant metastases in patients with locally advanced breast cancer. ¹⁸F-FDG PET/CT can add information about extra-axillary lymph node involvements.

Prevalence and clinical significance of incidental extra-mammary findings in breast magnetic resonance imaging: A retrospective study of 1070 patients

PURPOSE

The purpose of this study was to analyze the prevalence of extra-mammary findings in magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Data from 1070 consecutive breast MRI studies was analyzed. MR-BI-RADS (Breast Imaging Reporting and Data System) was used to classify the risk category.

RESULTS

According to MR-BI-RADS, 915 (85.5%) of 1070 women were classified into MR-BI-RADS categories 1-3, and 155 (14.5%) into MR-BI-RADS categories 4-5. MR-BI-RADS categories 4-5 had a 10-times higher risk for major extra-mammary findings (odds ratio 10.1, P<0.01).

CONCLUSION

Extra-mammary findings are common and may have important clinical consequences.

Retrospektive Analyse von Zufallsbefunden, die bei Patienten mit kutanem malignen Malignom durch (18) F-Fluordeoxyglucose-PET/CT erhoben wurden

HINTERGRUND UND ZIELE

Bei der (18) F-Fluordeoxyglucose-Positronenemissionstomographie/Computertomographie (FDG-PET/CT) ergeben sich häufig Zufallsbefunde. In der vorliegenden Studie konzentrierten wir uns auf mittels FDG-PET/CT erhaltene Zufallsbefunde bei Patienten mit kutanem Melanom und überprüften deren Relevanz hinsichtlich weiterer diagnostischer Maßnahmen und Interventionen.

PATIENTEN UND METHODEN

Die Krankenakten von 181 konsekutiven Melanom-Patienten wurden retrospektiv ausgewertet, um das Management von Zufallsbefunden zu dokumentieren. Der Schwerpunkt lag dabei auf den histologischen Befunden.

ERGEBNISSE

Bei 33 von 181 (18 %) Patienten lagen 39 relevante Zufallsbefunde vor, und zwar im Kolorektalbereich (n = 15 Patienten), in der Schilddrüse (n = 8), der Prostata (n = 2), dem Bewegungsapparat (n = 2), in Lymphknoten (n = 2), der Parotis (n = 1), den Mandeln (n = 1), den Nieren (n = 1) und der Gallenblase (n = 1). Bei 25 Patienten schlossen sich weitere diagnostische Verfahren an, wobei in 21 Fällen ein klinisches Korrelat nachgewiesen wurde. Bei 16 von 21 Patienten ergab sich eine Neoplasie, darunter fünf maligne Läsionen (vier Kolonkarzinome und ein Prostatakarzinom). Die Malignome wurden frühzeitig diagnostiziert und in der Mehrzahl der Fälle erfolgreich entfernt.

SCHLUSSFOLGERUNGEN

Der Einsatz der FDG-PET/CT als Routine-Diagnostik wird in den Leitlinien empfohlen und ist indiziert bei malignem Melanom ab Stadium IIC. In dieser Studie wurden auf effektive Weise ansonsten nicht erkannte Krebserkrankungen, insbesondere Kolonkarzinome, detektiert. In den meisten Fällen war eine frühe Intervention möglich. Zufallsbefunde durch FDG-PET/CT sollten, unter Berücksichtigung des Zustands und der Wünsche des Patienten, mit den geeigneten diagnostischen Maßnahmen abgeklärt werden.

Incidental head and neck findings on 18F-fluoro-deoxy-glucose positron emission tomography computed tomography

OBJECTIVE

The overlapping risk factors for lung and head and neck cancer present a definite risk of synchronous malignant pathology. This is the first study to specifically review incidental positron emission tomography computed tomography findings in the head and neck region in lung carcinoma patients.

METHODS

A retrospective review was performed of all lung cancer patients who underwent positron emission tomography computed tomography imaging over a five-year period (January 2008 - December 2012), identified from the Liverpool thoracic multidisciplinary team database.

RESULTS

Six hundred and nine patients underwent positron emission tomography computed tomography imaging over this period. In 76 (12.5 per cent) scans, incidental regions of avid 18F-fluoro-deoxy-glucose uptake were reported in the head and neck region. In the 28 patients who were fully investigated, there were 4 incidental findings of malignancy.

CONCLUSION

In lung cancer patients undergoing investigative positron emission tomography computed tomography scanning, a significant number will also present with areas of clinically significant 18F-fluoro-deoxy-glucose uptake in the head and neck region. Of these, at least 5 per cent may have an undiagnosed malignancy.

Predictors of pathologic outcome of focal FDG uptake in the parotid gland identified on whole-body FDG PET imaging

PURPOSE

The purpose was to test whether patient's primary malignancy type and presence of F-18-fluorodeoxyglucose (FDG)-avid cervical lymph node(s) are predictors of pathologic outcome of incidental focal FDG-avid parotid lesions.

BASIC PROCEDURES

A retrospective cohort study of pathologically proven incidental cases was performed.

MAIN FINDINGS

Focal parotid FDG uptake in the setting of head and neck cancer/melanoma [odds ratio (OR)=24.6, P<.01], lymphoma (OR=7.2, P=.02), or FDG-avid cervical lymph node(s) (OR=3.6, P=.07) has a higher odds of representing metastases. No malignant primary parotid tumors were incidentally discovered.

PRINCIPAL CONCLUSIONS

In patients with head and neck cancer/melanoma, lymphoma, or FDG-avid cervical lymph node(s), there were higher odds that focal parotid FDG uptake was a metastasis.

Incidental Breast Lesions Identified by (18)F-FDG PET/CT: Which Clinical Variables Differentiate between Benign and Malignant Breast Lesions?

Purpose

The aim of our study was to evaluate the risk of malignancy and to determine which clinical variables differentiate between benign and malignant focal breast lesions found incidentally on ¹⁸F-flourodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT).

Methods

From March 2005 to October 2011, 21,224 women with no history of breast cancer underwent FDG PET/CT at three university-affiliated hospitals. We retrospectively identified 214 patients with incidental focal hypermetabolic breast lesions and grouped them into benign and malignant lesion groups. Of the 214 patients, 82 patients with 91 lesions were included in this study. All lesions were confirmed histologically or were assessed by follow-up imaging for greater than 2 years. The patient age, maximum standardized uptake value (SUV_max), lesion size on ultrasonography (US), and Breast Imaging-Reporting and Data System (BI-RADS) category on US in conjunction with mammography were compared between the groups. Multivariate logistic regression analysis was used to identify independent factors associated with malignancy.

Results

The risk of malignancy was 29.7% (27/91) in breast incidentalomas detected by FDG PET/CT. The univariate analysis showed that the patient age, SUV_max, tumor size, and BI-RADS category differed significantly between the malignant and benign groups. The multivariate analysis showed that the BI-RADS category was the only significant factor differentiating benign from malignant lesions (p=0.002).

Conclusion

BIRADS category based on US in conjunction with mammography was the only useful tool to differentiate between malignant and benign lesions in breast incidentalomas on FDG PET/CT.

Clinical significance of patterns of incidental thyroid uptake at (18)F-FDG PET/CT

Incidental uptake of 2-[(18)F]-fluoro-2-deoxy-d-glucose ((18)F-FDG) in the thyroid gland is not uncommonly encountered in day-to-day practice of oncological (18)F-FDG positron-emission tomography/computed tomography (PET/CT). These are often felt to be "nuisance lesions" by referring clinicians and radiologists alike. However, recognition of the importance of different patterns of FDG uptake in the thyroid gland and knowledge of the possible underlying aetiologies are crucial in ensuring that patients are managed appropriately in the clinical context of their primary diagnosis, as the underlying pathological condition may be clinically important in a significant minority of such cases. This review describes the various patterns of (18)F-FDG uptake within the thyroid and discusses the clinical significance and possible impact on patient management. Incidental low-grade homogeneous diffuse increased thyroid (18)F-FDG uptake is usually seen in the patients with chronic thyroiditis, Grave's disease, and hypothyroidism. Thyroid function tests and antibody profiling are advised in these patients. Incidental focal (18)F-FDG thyroid uptake should raise the possibility of underlying malignancy. Ultrasound with or without fine-needle aspiration cytology is usually recommended for the evaluation of these lesions. Heterogeneous uptake with prominent focal uptake in the thyroid should be further evaluated to exclude malignancy.

Impact of incidental findings on integrated 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography in patients with gastric cancer

AIM

Since positron emission tomography/computed tomography (PET/CT) has been introduced, many incidental findings have been identified. The aim of this study was to assess the clinical significance of incidental findings on PET/CT in patients with gastric cancer.

METHODS

A total of 421 patients with gastric cancer underwent PET/CT for initial staging. Incidental findings on PET/CT were classified into five categories according to clinical significance--normal variant, benign, probably benign, probably malignant, and definitely malignant. We obtained information regarding follow-up examinations, additional visits, final diagnosis of incidental findings and short-term medical costs for further evaluation.

RESULTS

Eight hundred eighty-two incidental findings were detected in 386 (91.7%) patients. Of 274 incidental findings classified as probably benign, probably malignant or definitely malignant, 130 required one or more additional investigations. Finally, 12 (9.2%) were proved to be associated with second primary malignancy or metastasis of gastric cancer. One hundred twenty-nine additional outpatient visits and 10 additional hospitalizations were needed for evaluating the incidental findings. The treatment strategy for gastric cancer was changed in one patient. The estimated cost of additional investigations was $US283 (95% CI: $US248-$US311) per patient.

CONCLUSION

Incidental findings on PET/CT were common. Although the incidental findings were suspicious of malignancy, most were benign with high costs for additional investigations.

Ability of 18-fludeoxyglucose positron emission tomography/CT to detect incidental cancer

OBJECTIVE

To determine the prevalence and clinical features of pathologically proven incidental cancer (IC) detected by whole-body fluorine-18 fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT, as well as the incidence of false-positive and false-negative results.

METHODS

We retrospectively reviewed reports derived from (18)F-FDG PET/CT images of 3079 consecutive patients with known or suspected malignancies for 3 years. Discrete focal uptake indicating IC was identified from reports as well as pathological or clinical diagnoses, and the clinical courses were investigated. The false-positive result was defined as uptake indicating IC but not pathologically confirmed as malignant during follow-up. The false-negative result was defined as pathologically proven IC detected by another modality at initial clinical work-up or diagnosed during the follow-up period.

RESULTS

We found (18)F-FDG uptake indicating IC in 6.7% of all patients, and IC was pathologically proven in 2.2% of all patients. The most common sites were the colon, lung and stomach. The median survival duration of patients with IC was 42 months. The results were false positive in 4.5% of all patients, and the results were false negative in 2.3% of all patients.

CONCLUSION

(18)F-FDG PET/CT is a valuable tool for detecting IC. The rates of false-positive and false-negative results are within acceptable range.

ADVANCES IN KNOWLEDGE

This is the first report to describe the survival of patients with IC, and the detailed features of false-negative results at actual clinical settings.

Clinical significance of incidental findings on staging positron emission tomography for oesophagogastric malignancies

INTRODUCTION

The aim of this retrospective study was to determine the clinical significance of incidental findings detected on positron emission tomography (PET) in patients undergoing staging of oesophagogastric malignancies.

METHODS

Patients with oesophagogastric malignancies who underwent PET between June 2007 and May 2012 were included in the study. PET was performed according to hospital protocol. All imaging was interpreted by two consultant radiologists in nuclear medicine. Incidental findings that were unrelated to the primary malignancy were recorded and patients were recommended to have further investigations (imaging, endoscopy and biopsy).

RESULTS

Overall, 333 patients (240 male, 93 female; mean age: 67 years) with upper gastrointestinal malignancies were eligible for inclusion in the study. Eighty-nine of these patients had PET demonstrating one or more incidental findings. Two patients were found to have a second primary malignancy. One patient had a distant metastasis of his primary cancer and six patients had a premalignant lesion.

CONCLUSIONS

In this study, incidental findings were discovered in 26.7% of patients with known oesophagogastric cancer. A second primary cancer or premalignant lesion was found in 8.4% of patients with incidental findings. Patients with these findings should be investigated to rule out further malignancy. There were a high proportion of false positive results in our study. It is recommended that each patient is considered on an individual basis and assessed with simultaneous PET and computed tomography.

The Proportion of Malignancy in Incidental Thyroid Lesions on 18-FDG PET Study

Objective

To evaluate through a systematic review and meta-analysis the malignancy rates of thyroid incidentalomas identified in adults by 18-fluorodeoxyglucose positron emission tomography, computed tomography (18-FDG PET-CT) imaging studies.

Data Sources

The literature search was conducted using OVID Medline, EMBASE, the Cochrane Library, Google Scholar, Pubmed, and reference list review (inception to April 2013) by 2 independent review authors.

Review Methods

Studies with adults undergoing 18-FDG PET scan identifying a thyroid incidentaloma with definitive histological or cytological results reported were included.

Results

Thirty-one studies with a total of 197,296 PET studies and 3659 focal thyroid incidentalomas were identified with 1341 having definitive cytopathology or histopathology. The pooled proportion of malignancy was calculated as 19.8% (95% confidence interval [CI], 15.3%-24.7%) with 15.4% (95% CI, 11.4%-20.0%) of the total cases being papillary thyroid cancer. Distant metastases represented 1.1% (95% CI, 0.6%-1.8%) of the total cases.

Conclusions

Our systematic review and meta-analysis suggests that the incidence of malignancy is high in thyroid incidentalomas identified through 18-FDG PET imaging studies. Thyroid incidentalomas identified through 18-FDG PET require thorough investigation.

The pivotal role of FDG-PET/CT in modern medicine

The technology behind positron emission tomography (PET) and the most widely used tracer, 2-deoxy-2-[18F]fluoro-D-glucose (FDG), were both conceived in the 1970s, but the latest decade has witnessed a rapid emergence of FDG-PET as an effective imaging technique. This is not least due to the emergence of hybrid scanners combining PET with computed tomography (PET/CT). Molecular imaging has enormous potential for advancing biological research and patient care, and FDG-PET/CT is currently the most widely used technology in this domain. In this review, we discuss contemporary applications of FDG-PET and FDG-PET/CT as well as novel developments in quantification and potential future indications including the emerging new modality PET/magnetic resonance imaging.

Role of combined BI-RADS assessment using mammography and sonography for evaluation of incidental hypermetabolic lesions in the breast on 18F-FDG PET-CT

BACKGROUND

PET-CT is widely used for evaluation and follow-up of malignancy. Incidental hypermetabolic lesions are often found on PET-CT, some of which are confirmed to be malignant.

PURPOSE

To estimate the role of combined Breast Imaging-Reporting and Data System (BI-RADS) assessment using mammography and sonography for evaluation of incidental hypermetabolic lesions on 18F-FDG PET-CT and to determine an appropriate next step.

MATERIAL AND METHODS

This study included incidental hypermetabolic lesions found in the breasts of 7594 women who underwent PET-CT at three university-affiliated hospitals between January 2006 and December 2011. We reviewed the maximum standardized uptake value (SUVmax) of incidental lesions, combined BI-RADS assessment of mammography and sonography, and final results. We analyzed the negative predictive values of the probably benign (categories 1-3) group and the sensitivity of suspicious (categories 4 and 5) groups according to combined BI-RADS assessment.

RESULTS

Forty-three patients (0.6%) had 49 incidental hypermetabolic lesions in the breast. Histologic diagnosis in 17 patients confirmed nine breast cancers (27.3%). Sixteen patients underwent imaging follow-up for at least 2 years; no breast cancer was detected. Thirteen patients were lost to follow-up and were excluded. For the suspicious (n = 14) and probably benign (n = 19) groups according to combined BI-RADS assessment, both the sensitivity and negative predictive values were 100%. Using an optimal diagnostic cut-off value of 2.15, the malignancy rate was not significantly different (16.7% vs. 45.5%, respectively, in the group with SUVmax < 2.15 and the group with SUVmax ≥ 2.15; P > 0.05). The SUVmax of the confirmed malignant and assumed benign groups were not significantly different (3.1% vs. 2.2%, respectively; P > 0.05).

CONCLUSION

Both mammography and sonography should be considered the next step to evaluate incidental hypermetabolic lesions on 18F-FDG PET-CT because combined BI-RADS assessment provides an excellent negative predictive value for excluding malignancy.

Comparison between incidental malignant and benign breast lesions detected by computed tomography: a systematic review

INTRODUCTION

With increasing use of CT for a variety of diagnostic pathways, breast incidentalomas will be identified more frequently. Therefore, it is important for radiologists to know typical CT appearances of malignant and benign breast lesions. The aim of this study was to compare radiological features of benign and malignant incidental breast findings on CT reported in the literature.

METHODS

A search for appropriate studies published between 1988 and 2012 yielded five results with a total of 214 patients/257 lesions. Morphological features of the described breast masses, such as shape, margins, enhancement, axillary lymphadenopathy and calcifications, were analysed.

RESULTS

The prevalence of incidental breast carcinoma varied from 9.2% to 60.9% of the lesions. The frequency of benign lesions was 30.4-71.8%. The remaining incidental findings were intramammary metastases and primary or secondary breast lymphomas. Malignant lesions were larger in size, were round in shape and demonstrated a higher density compared with benign lesions. There was no significant difference in the margin characteristics of the masses between the groups. The morphological features previously postulated as typical for malignancy turned out to be non-specific.

CONCLUSIONS

Benign and malign breast incidentalomas are not safely distinguished from each other on standard chest CT. Therefore, all breast incidentalomas should be evaluated by further radiological/histological investigations.

That liver lesion on MDCT in the oncology patient: is it important?

Multidetector-row computed tomography (MDCT) has become the primary imaging test for the staging and follow-up of most malignancies that originate outside of the central nervous system. Technical advances in this imaging technique have led to significant improvement in the detection of metastatic disease to the liver. An unintended by-product of this improving diagnostic acumen is the discovery of incidental hepatic lesions in oncology patients that in the past remained undetected. These ubiquitous, incidentally identified hepatic lesions have created a management dilemma for both clinicians and radiologists: are these lesions benign or do they represent metastases? Naturally, the answer to this question has profound prognostic and therapeutic implications. In this review, guidelines concerning the diagnosis and management of some of the more common hepatic incidental lesions detected in patients with extrahepatic malignancies are presented.