Incidental abnormal FDG uptake in the prostate on 18-fluoro-2-deoxyglucose positron emission tomography-computed tomography scans

Definitions of Incidental [18F]FDG PET/CT Findings in the Literature: A Systematic Review and Definition Proposal

Objectives: The objectives of this study were (1) to systematically review the currently used definitions of incidental 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography findings (IPFs) in the literature and (2) to propose an IPF definition. Methods: A systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The search was guided by the question "How is IPF defined?" and was performed in MEDLINE, Embase, and the Cochrane Library. The retrieved studies were reviewed and analyzed. The definitions of IPFs in the included studies were compiled into two sets of categories based on the description of FDG uptake and the specification of clinical factors in defining IPFs. Results: The systematic literature search identified 4852 publications accessible for title-abstract screening, which yielded 395 studies for full-text assessment. Sixty-five studies met the eligibility criteria and were included. Sixty-two percent mentioned "FDG uptake" in their definition. In 40% of the definitions, "Focal FDG uptake" was specified, while "FDG uptake in the surrounding tissue" was included in 15%. Fifty-seven percent stated that IPFs were "Unrelated to PET/CT indication". Thirty-four percent specified IPFs as "Present in other organ than PET/CT indication", whereas 20% included "No known disease related to IPF". Seventeen percent of the definitions comprised a "New finding", while 15% and 11% encompassed a "Clinical asymptomatic patient" and "Not a metastasis", respectively. Finally, 5% of the definitions included "Potential clinical significance". Conclusions: No generally accepted definition of IPFs currently exists. We propose an IPF definition based on explicit FDG uptake and clinical patient-related factors.

Description of FDG and Prostate-Specific Membrane Antigen PET/CT Findings in Korean Patients With Advanced Metastatic Castration-Resistant Prostate Cancer

OBJECTIVE

We aimed to describe the [18F]fluorodeoxyglucose (FDG) and prostate-specific membrane antigen (PSMA) PET/CT findings in Korean men with advanced metastatic castration-resistant prostate cancer (mCRPC).

MATERIALS AND METHODS

The results of paired FDG and PSMA PET/CT examinations performed in 42 consecutive men with prostate cancer for treatment planning after failure of anti-androgen therapy and chemotherapy were studied. Tumor lesions with FDG or PSMA uptake intensity higher than that of the liver on visual review were considered positive and noted per patient and tumor site (prostate bed, lymph node, bone, and visceral organ). The presence of unequivocally discordant FDG and PSMA uptake patterns in tumor lesions was assessed. Patients were grouped according to the total tumor volume as seen on each PET/CT scan, and the clinical findings between the patient groups were compared using the Mann-Whitney U test.

RESULTS

On patient-based analysis, the image findings were PSMA+/FDG- in 2 patients, PSMA-/FDG+ in one, and PSMA+/FDG+ in 39 patients. On site-based analysis, the discordance (PSMA+/FDG- or PSMA-/FDG+) rate was 9.5% (4/42) for prostate/bed, 11.9% (5/42) for lymph nodes, 9.5% (4/42) for bones, and 11.9% (5/42) for visceral organs. FDG uptake was higher than PSMA uptake in at least one tumor site in 54.8% (23/42) of patients. Patients with greater total tumor volume on FDG PET/CT than that on PSMA PET/CT ("FDG-dominant pattern") accounted for 28.6% (12/42), and they had significantly shorter time from diagnosis (median 25 months vs. 62 months, P = 0.049), and higher aspartate aminotransferase (median 28.5 vs. 22.5, P = 0.027) and lactate dehydrogenase (median 341.5 vs. 224.5, P = 0.010) levels.

CONCLUSION

Most patients with advanced mCRPC had tumors with positive findings on both FDG and PSMA PET/CT. However, the uptake patterns varied; 54.8% of the patients had tumor(s) with FDG uptake greater than PSMA uptake, and FDG-dominant pattern was noted in 28.6% of the patients.

Febrile Immunocompromised Renal Transplant Recipient with Allograft Dysfunction: Detection of an Undiagnosed Prostate Abscess by [ 18 F]FDG-PET/CT along with Treatment Response Monitoring

The purpose of this report is to provide a comprehensive description of a post-transplant febrile patient's clinical course, complications, surgical procedure, and long-term management including evaluation by 18 F-fluorodeoxyglucose [( 18 F)FDG] positron-emission tomography combined with computed tomography (PET/CT). A 35-year-old male, a postrenal transplant patient, developed chronic allograft dysfunction and presented with fever with chills, with suspicion of acute-on-chronic graft dysfunction, but no infective focus localization on chest X-ray, ultrasonography (USG) whole abdomen, or blood culture. Urine microscopy showed 8 to 10 pus cells/high-power field (hpf) and culture showed Klebsiella pneumoniae and Pseudomonas aeruginosa with low colony count. Culture-sensitive antibiotics were prescribed for 2 weeks, and after 3 weeks febrile episodes relapsed, symptoms progressed, and required emergency hospitalization due to acute painful urinary retention. Proteinuria and no growth were noted in urine analysis, serum creatinine was 5.36 mg/dL, and C-reactive protein was 15.7mg/dL, and remaining parameters were unremarkable. [ 18 F]FDG-PET/CT was considered in order to resolve diagnosis, which revealed abnormal heterogeneous tracer uptake in the enlarged prostate with hypodense areas within, suggesting prostatitis with abscess formation and pyelonephritis in the upper pole of the transplant kidney. USG kidney urinary bladder (KUB) correlation confirmed prostatic abscess and transurethral drainage done, and pus culture revealed Burkholderia pseudomallei . Culture-sensitive intravenous meropenem treatment was given for 3 weeks. At 5 weeks, follow-up [ 18 F]FDG-PET/CT showed low metabolic residual prostate uptake, suggesting a good response with residual infection. Thus, intravenous antibiotics was changed to oral antibiotics for another 6 weeks. His symptoms completely resolved at the end of treatment; however, his graft function worsened, with serum creatinine reaching 6 to 7 mg/dL, and eventually, after 8 months he became dialysis dependent.

Unexpected focal fluorodeoxyglucose uptake in main organs; pass through or pass by?

Since the inception of fluorine-18 fluorodeoxyglucose (F-18 FDG), positron emission tomography/computed tomography (PET/CT) utilizing F-18 FDG has become widely accepted as a valuable imaging modality in the field of oncology, with global prevalence in clinical practice. Given that a single Torso PET/CT scan encompasses the anatomical region from the skull base to the upper thigh, the detection of incidental abnormal focal hypermetabolism in areas of limited clinical interest is both feasible and not uncommon. Numerous investigations have been undertaken to delineate the distinctive features of these findings, yet the outcomes have proven inconclusive. The incongruent results of these studies present a challenge for physicians, leaving them uncertain about the appropriate course of action. This article provides a succinct overview of the characteristics of fluorodeoxyglucose, followed by a comprehensive discussion of the imaging findings and clinical significance associated with incidental focal abnormal F-18 FDG activity in several representative organs. In conclusion, while the prevalence of unrecognized malignancy varies across organs, malignancies account for a substantial proportion, ranging from approximately one-third to over half, of incidental focal uptake. In light of these rates, physicians are urged to exercise vigilance in not disregarding unexpected uptake, facilitating more assured clinical decisions, and advocating for further active evaluation.

SPECT Imaging with Tc-99m-Labeled HYNIC-FAPI-04 to Extend the Differential Time Window in Evaluating Tumor Fibrosis

The so-far used Ga-68- or F-18-labelled tracers are of a relative short time window in differentiating tumor fibrosis. SPECT applicable imaging probe, 99mTc-HYNIC-FAPI-04, was synthesized and evaluated in tumor cells and animal models of FAP-positive glioma and FAP-negative hepatoma, and then compared with 18F-FDG or 68Ga-FAPI-04 PET/CT. The radio-labeling rate of 99mTc-HYNIC-FAPI-04 was greater than 90%, and the radiochemical purity was >99% after purification with sep-pak C18 column. In vitro cell uptake experiments of 99mTc-HYNIC-FAPI-04 showed good FAP binding specificity, and the cellular uptake significantly decreased when blocked by DOTA-FAPI-04, reflecting the similar targeting mechanism of HYNIC-FAPI-04 and DOTA-FAPI-04. SPECT/CT imaging showed that U87MG tumor was distinguishable and of a high uptake of 99mTc-HYNIC-FAPI-04 (2.67 ± 0.35 %ID/mL at 1.5 h post injection (h P.I.), while tumor signal of FAP-negative HUH-7 was as low as 0.34 ± 0.06 %ID/mL. At 5 h P.I., U87MG tumor was still distinguishable (1.81 ± 0.20 %ID/mL). In comparison, although U87MG tumor was of obvious 68Ga-FAPI-04 uptake and clearly visible at 1 h P.I., the tumorous radioactive signals were fuzzy at 1.5 h P.I. 99mTc-HYNIC-FAPI-04 specifically bound to FAP-positive tumors and qualified with the ability of evaluating tumor fibrosis over longer time windows.

Significance of incidental focal fluorine-18 fluorodeoxyglucose uptake in colon/rectum, thyroid, and prostate: With a brief literature review

BACKGROUND

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT), a functional imaging method, is usually performed on the entire torso, and regions of unexpected suspicious focal hypermetabolism are not infrequently observed. Among the regions, colon, thyroid, and prostate were found to be the common organs in a recent umbrella review. Some studies reported that a high rate of malignancy was shown in incidentally identified focal hypermetabolic regions and suggested that further examinations should not be ignored.

AIM

To investigate the malignancy rate of incidental focal FDG uptake, useful PET parameters and their cutoffs in discrimination between malignant and benign lesions.

METHODS

Retrospectively, the final reports of 16510 F-18 FDG PET/CT scans performed at our hospital between January 2016 and March 2022 were reviewed to identify incidentally observed FDG uptake in the colon/rectum, thyroid, and prostate. The scans of patients with current or prior malignancies at each corresponding location, without the final reports of histopathology or colonoscopy (for colon and rectum) for the corresponding hypermetabolic regions, or with diffuse (not focal) hypermetabolism were excluded. Finally, 88 regions of focal colorectal hypermetabolism in 85 patients (48 men and 37 women with mean age 67.0 ± 13.4 years and 63.4 ± 15.8 years, respectively), 48 focal thyroid uptakes in 48 patients (12 men and 36 women with mean age 62.2 ± 13.1 years and 60.8 ± 12.4 years, respectively), and 39 focal prostate uptakes in 39 patients (mean age 71.8 ± 7.5 years) were eligible for this study. For those unexpected focal hypermetabolic regions, rates of malignancy were calculated, PET parameters, such as standardized uptake value (SUV), capable of distinguishing between malignant and benign lesions were investigated, and the cutoffs of those PET parameters were determined by plotting receiver operating characteristic curves.

RESULTS

In the colon and rectum, 29.5% (26/88) were malignant and 33.0% (29/88) were premalignant lesions. Both SUVmax and SUVpeak differentiated malignant/premalignant from benign lesions, however, no parameters could distinguish malignant from premalignant lesions. Higher area under the curve was shown with SUVmax (0.752, 95%CI: 0.649-0.856, P < 0.001) and the cutoff was 7.6. In the thyroid, 60.4% (29/48) were malignant. The majority were well-differentiated thyroid cancers (89.7%, 26/29). The results of BRAF mutation tests were available for 20 of the 26 well-differentiated thyroid cancers and all 20 had the mutation. Solely SUVmax differentiated malignant from benign lesions and the cutoff was 6.9. In the prostate, 56.4% (22/39) were malignant. Only SUVmax differentiated malignant from benign lesions and the cutoff was 3.8. Overall, among the 175 focal hypermetabolic regions, 60.6% (106/175) were proven to be malignant and premalignant (in colon and rectum) lesions.

CONCLUSION

Approximately 60% of the incidentally observed focal F-18 FDG uptake in the colon/rectum, thyroid, and prostate were found to be malignant. Of the several PET parameters, SUVmax was superior to others in distinguishing between malignant/premalignant and benign lesions. Based on these findings, incidental focal hypermetabolism should not be ignored and lead physicians to conduct further investigations with greater confidence.

Dual-Tracer PET-Computed Tomography Imaging for Precision Radio-Molecular Theranostics of Prostate Cancer: A Futuristic Perspective

Dual/multi-tracer PET-computed tomography (CT) scan has been an interesting and intriguing concept and is promising in noninvasive and overall characterization of tumor biology and heterogeneity and has scientifically augmented the practice of precision oncology. In prostate carcinoma, particularly in metastatic castration-resistant prostate carcinoma setting, dual-tracer PET-CT can be potentially useful in selecting patients for chemotherapy, androgen deprivation therapy or prostate-specific membrane antigen (PSMA)-based peptide receptor radioligand therapy either as mono-therapy or as combination therapy, ascertaining differentiation status, staging/restaging, prognostication, and predicting progression/response. PSMA PET/CT has great potential as a "rule out" test in baseline staging, while being very useful in restaging and metastatic workup.

Prostate incidentaloma on 18F-fluorodeoxyglucose positron emission tomography: Diagnostic value of volumetric positron emission tomography parameters

OBJECTIVE

To evaluate whether volumetric PET parameters such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG) contributed to maximum standardized uptake value (SUVmax) in predicting prostate carcinoma in the prostate incidentalomas (PI) in 18F-FDG PET/CT.

MATERIALS AND METHODS

This retrospective study comprised 107 patients with PI of 4723 male patients who had undergone 18F-FDG PET/CT. SUVmax and volumetric PET parameters of PIs were assessed. MTV and TLG were acquired with each SUV threshold as 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0.

RESULTS

The PI incidence was 2.3%, and the malignancy ratio of PI was 15.9%. According to further analysis results, 17 patients were in the malignant group, and 46 patients were in the benign group. Malignant PIs had higher SUVmax (10.6 vs. 6.4 and p<0.01), MTV (all p < 0.01) and TLG (all p < 0.01) than benign incidentalomas. All volumetric PET parameters had higher area under the curve (AUC) than SUVmax. SUVmax AUC was 0.835 [95% confidence interval (CI): 0.728-0.942]. MTV 2.5 and TLG 2.5 had the highest performance for predicting malignant PI.MTV2.5 AUC was 0.871 (95% CI: 0.775-0.968), and TLG2.5 AUC was 0.882 (95% CI: 0.797-0.967). Using TLG 2.5 greater than 29.8 as the cut-off point, the sensitivity and specificity for malignancy prediction were 94.1% and 82.6%, respectively.

CONCLUSION

In this study, in which the effectiveness of volumetric parameters in the diagnosis of PI was evaluated for the first time, it was shown that they could potentially have clinical value along with SUVmax.

Critical Role of 2-[18F]-fluoro-2-deoxy-glucose in Hormonally Active Malignancies

2-[18F]-fluoro-2-deoxyglucose (FDG) is the most commonly used radiotracer and provides valuable information about glucose metabolism. With the advent of newer receptor-based tracers in the management of hormonally active malignancies, the focus has been shifted from FDG. These tracers might be more specific than FDG because they target specific hormone receptors. But because FDG is widely available, this review discusses what information still can be harnessed from this workhorse of molecular imaging. The personalized implementation of FDG imaging in undifferentiated malignancies will help in characterization of tumor and may aid in patient management.

Clinical significance of prostate 18F-labelled fluorodeoxyglucose uptake on positron emission tomography/computed tomography: A five-year review

AIM

To determine the significance and need for investigation of incidental prostatic uptake in men undergoing 18F-labelled fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for other indications.

METHODS

Hospital databases were searched over a 5-year period for patients undergoing both PET/CT and prostate magnetic resonance imaging (MRI). For the initial analysis, the prostate was divided into six sectors and suspicious or malignant sectors were identified using MRI and histopathology reports respectively. Maximum and mean 18F-FDG standardised uptake values were measured in each sector by an investigator blinded to the MRI and histopathology findings. Two age-matched controls were selected per case. Results were analysed using a paired t-test and one-way ANOVA. For the second analysis, PET/CT reports were searched for prostatic uptake reported incidentally and these patients were followed up.

RESULTS

Over a 5-year period, 15 patients underwent both PET/CT and MRI and had biopsy-proven prostate cancer. Malignant prostatic sectors had a trend to higher 18F-FDG uptake than benign sectors, however this was neither clinically nor statistically significant (3.13 ± 0.58 vs 2.86 ± 0.68, P > 0.05). 18F-FDG uptake showed no correlation with the presence or histopathological grade of tumour. 18F-FDG uptake in cases with prostate cancer was comparable to that from age-matched controls. Forty-six (1.6%) of 2846 PET/CTs over a 5-year period reported incidental prostatic uptake. Of these, 18 (0.6%) were investigated by PSA, 9 (0.3%) were referred to urology, with 3 (0.1%) undergoing MRI and/or biopsy. No cases of prostate cancer were diagnosed in patients with incidental 18F-FDG uptake in our institute over a 5-year period.

CONCLUSION

18F-FDG uptake overlaps significantly between malignant and benign prostatic conditions. Subsequent patient management was not affected by the reporting of incidental focal prostatic uptake in this cohort.

Case: Incidental 18F-fluorodeoxyglucose-positron emission tomography/computed tomography prostate uptake: How should these patients be managed?

18F-fluorodeoxyglucose-positron emission tomography/ computed tomography (18F-FDG PET/CT) is a widely used diagnostic tool for whole-body imaging, and incidental prostatic uptake occurs in approximately 1% of patients undergoing the exam. Is 18F-FDG PET/CT a reliable screening tool for prostate cancer? Should these patients undergo transrectal ultrasound (TRUS)-guided prostate biopsies? Studies have indicated that 18F-FDG PET/CT has a low positive predictive value for prostate cancer and is not recommended for screening;1 however, other studies suggest that when a discrete focal 18F-FDG uptake is discovered without coincidental calcification, particularly in the peripheral zone of the prostate, further clinical evaluation is recommended. We present two patients with incidental 18F-FDG PET/CT prostatic uptake who were found to have high-grade prostate cancer. Although 18F-FDG PET/CT has not been determined to be a reliable screening tool for prostate cancer, patients with incidental 18F-FDG uptake in the prostate should be referred for urological evaluation.

PET of Glucose Metabolism and Cellular Proliferation in Prostate Cancer

Imaging of the Warburg effect, which is the principal but not the sole cause for enhanced glucose metabolism in tumors, with PET and ¹⁸F-FDG has become the mainstay for the imaging evaluation of several cancers. Despite the seemingly prevalent notion that ¹⁸F-FDG PET may not be useful in prostate cancer, relatively limited evidence suggests that this imaging modality can be useful for the evaluation of the extent of metastatic disease and the assessment of the therapy response and prognosis in men with castration-resistant prostate cancer. Incidental high focal ¹⁸F-FDG uptake in the prostate gland, although generally rare, may also indicate occult prostate cancer that may need to be further scrutinized. In general, ¹⁸F-FDG PET is not useful for initial staging and is of limited utility in the clinical setting of biochemical failure after prior definitive therapy for primary cancer. Although more experience is needed, it appears that the imaging of cellular proliferation with PET and 3'-deoxy-3'-¹⁸F-fluorothymidine or 2'-¹⁸F-fluoro-5-methyl-1-β-d-arabinofuranosyluracil may also allow for targeted biopsy and localization for focal therapy of aggressive prostate tumors as well as assessment of the therapy response to various standard and novel treatment regimens in patients with metastatic disease.

Is There Use for FDG-PET in Prostate Cancer?

The use of positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG) in prostate cancer depends on the phase of the disease along the natural history of this prevalent malignancy in men. Incidental high FDG uptake in the prostate gland, although rare, should prompt further investigation with at least a measurement of serum prostate specific antigen level. Although in general FDG uptake level may significantly overlap among normal, benign, and malignant tissues, aggressive primary tumors with Gleason score > 7 tend to display high FDG uptake. PET with FDG may be useful in staging of those patients with aggressive primary tumors and can localize the site of disease in a small fraction of men with biochemical failure and negative conventional imaging studies. FDG-PET may be quite useful in treatment response assessment and prognostication of patients with castrate-resistant metastatic prostate cancer.

Importance of PET/CT scan use in planning radiation therapy for lymphoma

BACKGROUND

Radiation therapy is a key part of the combined modality treatment for Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL), which can achieve locoregional control of disease. The 3D-conformal radiation oncology can be extended-field (EFRT), involved-field (IFRT) and involved node (INRT). New techniques have resulted in a smaller radiation field and lower dose for critical organs such as lung heart and breast.

MATERIALS AND METHODS

In our research, we made a virtual simulation for one patient who was treated in four different radiotherapeutic techniques: mantle field (MFRT), EFRT, IFRT and INRT. After delineatiion we compared dose-volume histograms for each technique. The fusion of CT for planning radiotherapy with the initial PET/CT was made using Softver Xio 4.6 in the Focal program. The dose for all four techniques was 36Gy.

RESULTS

Our results support the use of PET/CT in radiation therapy planning. With IFRT and INRT, the burden on the organs at risk is less than with MFRT and EFRT. On the other hand, the dose distribution in the target volume is much better with the latter.

CONCLUSIONS

The aim of modern radiotherapy of HL and NHL is to reduce the intensity of treatment and therefore PET/CT should be used to reduce and not increase the amount of tissue receiving radiation.

Clinical Relevance of Incidental Prostatic Lesions on FDG-Positron Emission Tomography/Computerized Tomography-Should Patients Receive Further Evaluation?

PURPOSE

FDG ((18)F-fluoro-2-deoxy-D-glucose)-PET/CT (positron emission tomography)/(computerized tomography) is a widely used diagnostic tool for whole body imaging. Incidental prostatic uptake is often found on FDG-PET/CT. The objective of this study was to determine the clinical relevance of incidental prostatic uptake on FDG-PET/CT.

MATERIALS AND METHODS

We analyzed 108 consecutive male patients with bladder cancer who underwent FDG-PET/CT and subsequently radical cystoprostatectomy between May 2009 and November 2014. PET/CT scans were blindly reviewed by a dedicated nuclear medicine physician for incidental prostatic FDG uptake. If present, the maximum standardized uptake value was determined. Subsequently incidental prostatic uptake was categorized as suspect, indeterminate or nonsuspect for prostate cancer.

RESULTS

Incidental prostatic uptake was present in 43 of 108 patients (40%). Of these 43 patients 13 (30%) had occult prostate cancer in cystoprostatectomy specimens. Overall prostate cancer was found in 25 of 108 specimens (23%). If all incidental prostatic uptake was regarded as prostate cancer, the sensitivity and specificity of FDG-PET/CT for prostate cancer detection were 52% and 64%, respectively. Positive and negative predictive values were 30% and 82%, respectively. If only lesions labeled suspect or indeterminate were regarded as prostate cancer, sensitivity, specificity, and positive and negative predictive values were 32%, 76%, 29% and 79%, respectively. Categorizing indeterminate lesions as nonprostate cancer did not improve diagnostic accuracy. Gleason score did not correlate with maximum standardized uptake value or serum prostate specific antigen.

CONCLUSIONS

Incidental prostatic uptake on FDG-PET/CT has a low positive predictive value for prostate cancer. An attempt to classify lesions as suspect or nonsuspect did not increase diagnostic accuracy. Based on these results physicians should be cautious about applying invasive diagnostic methods to detect prostate cancer in case of incidental prostatic uptake on FDG-PET/CT.

Multicentre study of 18F-FDG-PET/CT prostate incidental uptake

AIM

The purpose of our study was to establish the prevalence and pathological nature of fluorine-18-fluorodeoxyglucose (18F-FDG) prostate incidental uptake (PIU) among patients studied for non-prostate-malignant purposes in three nuclear medicine centres.

METHODS

We retrospectively evaluated 20,422 scans performed on male patients; all patients underwent 18F-FDG-PET/CT for purposes not related to prostate disease.

RESULTS

Among 20,422 patients PIU was identified for 280 (1.4 %) with an average age of 70 ± 10.7 years. Sixty-three of the 280 patients with PIU (22.5 %) underwent PSA dosage and biopsy to determine the nature of the incidental uptake. Thirty-five of the 63 (55.5 %) PIU were malignant whereas 28/63 (44.5 %) were benign. The average value of PSA for patients with benign PIU was 3.7 ± 2.8 ng/ml whereas it was 7.8 ± 8.2 ng/ml in patients with malignant PIU; this difference was statistically significant. For malignant lesions, the average lesion-to-liver SUVmax ratio was 2.9 ± 2.5 and the average lesion-to-blood-pool SUVmax ratio was 3.7 ± 2.5. For benign lesions, the average lesion-to-liver SUVmax ratio was 2.5 ± 1.7 and the average lesion-to-blood-pool SUVmax ratio was 3.5 ± 2.4; there was no statistically significant difference between lesion-to-liver and lesion-to-blood-pool SUVmax ratios for benign and malignant lesions.

CONCLUSION

Because PIU values are indicative of malignancy for a substantial percentage of patients, further investigation is required.