Correlation of apparent diffusion coefficients measured by 3T diffusion-weighted MRI and SUV from FDG PET/CT in primary cervical cancer

Purpose  Diffusion-weighted magnetic resonance imaging (DWI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) are oncological feasible techniques. Currently, apparent diffusion coefficient (ADC) measured by DWI and standard uptake value (SUV) from FDG PET/CT have similar applications in clinical oncology. The aim of this study was to assess the correlation between ADC and SUV in primary cervical cancer. Materials and methods  Patients with documented primary cervical cancer were recruited. All participants underwent abdominopelvic DWI at 3T and FDG PET/CT within 2 weeks. For the primary tumor, ADC was measured as minimum ADC (ADC_min) and mean ADC (ADC_mean) within the whole tumor by DWI. Maximum SUV (SUV_max) and mean SUV (SUV_mean) were measured by FDG PET/CT. Results  A total of 33 patients were included. There was no significant correlation either between ADC_min and SUV_max or between ADC_mean and SUV_mean. The relative ADC_min (rADC_min) defined as ADC_min/ADC_mean ratio was significantly inversely correlated with the relative SUV_max (rSUV_max) defined as SUV_max/SUV_mean ratio (r = –0.526, P = 0.0017) in all study patients. A significantly inverse correlation between rADC_min and rSUV_max was observed in patients with adenocarcinoma/adenosquamous carcinoma (r = –0.685, P = 0.0012) and those with well-to-moderate differentiated tumor (r = –0.631, P = 0.0050). No significant correlation was demonstrated in patients with squamous cell carcinoma or poorly differentiated tumor. Conclusions  The significantly inverse correlation between rADC_min and rSUV_max in primary cervical tumor suggests that DWI and FDG PET/CT might play a complementary role for the clinical assessment of this cancer type.     

A case–control evaluation of pulmonary and extrapulmonary findings of incidental asymptomatic COVID-19 infection on FDG PET-CT

Objectives:To describe the findings of incidental asymptomatic COVID-19 infection on FDG PET-CT using a case–control design.Methods:Incidental pulmonary findings suspicious of asymptomatic COVID-19 infection on FDG PET-CT were classified as a confirmed (positive RT-PCR test) or suspected case (no/negative RT-PCR test). Control cases were identified using a 4:1 control:case ratio. Pulmonary findings were re-categorised by two reporters using the BSTI classification. SUV metrics in ground glass opacification (GGO)/consolidation (where present), background lung, intrathoracic nodes, liver, spleen and bone marrow were measured.Results:7/9 confirmed and 11/15 suspected cases (COVID-19 group) were re-categorised as BSTI 1 (classic/probable COVID-19) or BSTI 2 (indeterminate COVID-19); 0/96 control cases were categorised as BSTI 1. Agreement between two reporters using the BSTI classification was almost perfect (weighted κ = 0.94). SUV_max GGO/consolidation (5.1 vs 2.2; p < 0.0001) and target-to-background ratio, normalised to liver SUV_mean (2.4 vs 1.0; p < 0.0001) were higher in the BSTI 1 & 2 group vs BSTI 3 (non-COVID-19) cases. SUV_max GGO/consolidation discriminated between the BSTI 1 & 2 group vs BSTI 3 (non-COVID-19) cases with high accuracy (AUC = 0.93). SUV metrics were higher (p < 0.05) in the COVID-19 group vs control cases in the lungs, intrathoracic nodes and spleen.Conclusion:Asymptomatic COVID-19 infection on FDG PET-CT is characterised by bilateral areas of FDG avid (intensity > x2 liver SUV_mean) GGO/consolidation and can be identified with high interobserver agreement using the BSTI classification. There is generalised background inflammation within the lungs, intrathoracic nodes and spleen.Advances in knowledge:Incidental asymptomatic COVID-19 infection on FDG PET-CT, characterised by bilateral areas of ground glass opacification and consolidation, can be identified with high reproducibility using the BSTI classification. The intensity of associated FDG uptake (>x2 liver SUV_mean) provides high discriminative ability in differentiating such cases from pulmonary findings in a non-COVID-19 pattern. Asymptomatic COVID-19 infection causes a generalised background inflammation within the mid-lower zones of the lungs, hilar and central mediastinal nodal stations, and spleen on FDG PET-CT.     

FDG uptake heterogeneity evaluated by fractal analysis improves the differential diagnosis of pulmonary nodules

Purpose

The present study aimed to determine whether fractal analysis of morphological complexity and intratumoral heterogeneity of FDG uptake can help to differentiate malignant from benign pulmonary nodules.

Materials and methods

We retrospectively analyzed data from 54 patients with suspected non-small cell lung cancer (NSCLC) who were examined by FDG PET/CT. Pathological assessments of biopsy specimens confirmed 35 and 19 nodules as NSCLC and inflammatory lesions, respectively. The morphological fractal dimension (m-FD), maximum standardized uptake value (SUV_max) and density fractal dimension (d-FD) of target nodules were calculated from CT and PET images. Fractal dimension is a quantitative index of morphological complexity and tracer uptake heterogeneity; higher values indicate increased complexity and heterogeneity.

Results

The m-FD, SUV_max and d-FD significantly differed between malignant and benign pulmonary nodules (p < 0.05). Although the diagnostic ability was better for d-FD than m-FD and SUV_max, the difference did not reach statistical significance. Tumor size correlated significantly with SUV_max (r = 0.51, p < 0.05), but not with either m-FD or d-FD. Furthermore, m-FD combined with either SUV_max or d-FD improved diagnostic accuracy to 92.6% and 94.4%, respectively.

Conclusion

The d-FD of intratumoral heterogeneity of FDG uptake can help to differentially diagnose malignant and benign pulmonary nodules. The SUV_max and d-FD obtained from FDG-PET images provide different types of information that are equally useful for differential diagnoses. Furthermore, the morphological complexity determined by CT combined with heterogeneous FDG uptake determined by PET improved diagnostic accuracy.     

Hepatic steatosis is associated with increased hepatic FDG uptake

ObjectiveThe use of liver as a reference tissue for semi-quantification of tumour FDG uptake may not be valid in hepatic steatosis (HS). Previous studies on the relation between liver FDG uptake and HS have been contradictory probably because they ignored blood glucose (BG). Because hepatocyte and blood FDG concentrations equalize, liver FDG uptake parallels BG, which must therefore be considered when studying hepatic FDG uptake. We therefore re-examined the relation between HS and liver uptake taking BG into account.MethodsThis was a retrospective study of 304 patients undergoing routine PET/CT with imaging 60 min post-FDG. Average standard uptake value (SUV_ave), maximum SUV (SUV_max) and CT density (index of HS) were measured in a liver ROI. Blood pool SUV was based on the left ventricular cavity (SUV_LV). Correlations were assessed using least squares fitting of continuous data. Patients were also divided into BG subgroups (<4, 4–5, 5–6, 6–8, 8–10 and 10+ mmol/l).ResultsSUV_ave, SUV_max and SUV_LV displayed similar relations with BG. SUV_max/SUV_LV, but not SUV_ave/SUV_LV, correlated significantly with BG. SUV_max, but not SUV_ave, correlated inversely with CT density before and after adjusting for BG. SUV_max/SUV_ave correlated more strongly with CT density than SUV_max. CT density correlated inversely with SUV_max/SUV_LV but positively with SUV_ave/SUV_LV.ConclusionsHepatic SUV is more influenced by BG than by HS. Its relation with BG renders it unsuitable as a reference tissue. Nevertheless, hepatic fat does correlate positively with liver SUV, although this is seen only with SUV_max because SUV_ave is ‘diluted’ by hepatic fat.     

Dual-time-point [18F]-FDG PET/CT in the diagnostic evaluation of suspicious breast lesions

Purpose

The authors sought to evaluate whether the reacquisition of images 3 h after administration of radiotracer improves the sensitivity of fluorine-18 fluorodeoxyglucose positron emission tomography computed tomography ([¹⁸F]-FDG PET/CT) in patients with suspicious breast lesions.

Materials and methods

Forty-eight patients with 59 breast lesions underwent an [¹⁸F]-FDG PET/CT study in the prone position with a dual-time-point acquisition performed in the early phase 1 h after FDG administration (PET-1) and in the delayed phase 3 h after FDG administration (PET-2). Both examinations were evaluated qualitatively and semiquantitatively with calculation of the mean percentage variation of the standard uptake values (Δ% SUV_max) between PET-1 and PET-2. All lesions with an SUV_max ≥2.5 at PET-1 or a reduction in SUV between PET-1 and PET-2 were considered benign. The definitive histopathological diagnosis was available for all patients included in the study.

Results

The dual-time-point acquisition of [¹⁸F]-FDG PET/CT displayed an accuracy of 85% for lesions with an SUV_max ≥2.5 and/or positive Δ% SUV_max, with sensitivity and specificity values of 81% and 100% compared with 69%, 63% (both p<0.001) and 100% (p=n.s.), respectively, for the single-time-point acquisition. Malignant lesions showed an increase in FDG uptake between PET-1 and PET-2, with a Δ% SUV_max of 10±7 (p<0.04). In contrast, benign lesions showed a decrease in SUV between PET-1 and PET-2, with aΔ% SUV_max of ?21±7 (p<0.001).

Conclusions

The delayed repeat acquisition of PET images improves the accuracy of [¹⁸F]-FDG PET/CT in patients with suspicious breast lesions with respect to the single-time-point acquisition. In addition, malignant breast lesions displayed an increase in FDG uptake over time, whereas benign lesions showed a reduction. These variations in FDG uptake between PET-1 and PET-2 are a reliable parameter that can be used for differentiating between benign and malignant breast lesions.     

Application of Quantitative Indexes of FDG PET to Treatment Response Evaluation in Indolent Lymphoma

Purpose

Although ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a standard imaging modality for response evaluation in FDG-avid lymphoma, there is a controversy using FDG PET in indolent lymphoma. The purpose of this study was to investigate the effectiveness of quantitative indexes on FDG PET in response evaluation of the indolent lymphoma.

Methods

Fifty-seven indolent lymphoma patients who completed chemotherapy were retrospectively enrolled. FDG PET/computed tomography (CT) scans were performed at baseline, interim, and end of treatment (EOT). Response was determined by Lugano classification, and progression-free survival (PFS) by follow-up data. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured in the single hottest lesion (target A) or five hottest lesions (target B). Their efficacies regarding response evaluation and PFS prediction were evaluated.

Results

On EOT PET, SUV_max, and MTV of both targets were well associated with visual analysis. Changes between initial and EOT PET were not significantly different between CR and non-CR groups. On interim PET, SUV_max, and %ΔSUV_max in both targets were significantly different between CR and non-CR groups. For prediction of PFS, most tested indexes were significant on EOT and interim PET, with SUV_max being the most significant prognostic factor.

Conclusion

Quantitative indexes of FDG PET are well associated with Lugano classification in indolent lymphoma. SUV_max measured in the single hottest lesion can be effective in response evaluation and prognosis prediction on interim and EOT PET.

     

Incidental pituitary uptake on whole-body 18F-FDG PET/CT: a multicentre study

Purpose

The purpose of this study was to determine the incidence of incidental pituitary uptake on whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and to investigate its clinical significance.

Methods

The files of 40,967 patients who underwent whole-body FDG PET/CT were retrospectively reviewed. Quantification of pituitary metabolic activity was obtained by using the maximum standardized uptake value (SUV_max). Hormone assays and pituitary MRIs were performed to assess pituitary lesions.

Results

Focally increased pituitary FDG uptake on PET/CT was found in 30 of 40,967 patients, accounting for an incidence of 0.073%. The mean SUV_max of 30 patients was 8.9?±?6.6 (range: 3.2–32.6). Histological diagnosis was obtained in three patients and included two growth hormone-secreting adenomas and one non-functioning adenoma. Hormone assays were performed on serum samples from 11 patients, 2 of whom were shown to have hypersecretion of pituitary hormone. MRI was performed on 19 patients. Abnormal MRI findings suggesting a pituitary mass were found in 18 of 19 cases (94.7%). The mean SUV_max calculated without correction for partial volume effect for macroadenomas was significantly higher than the SUV_max for microadenomas (11.5?±?8.4 vs 4.8?±?1.3; p?<?0.05). There were no cases diagnosed with metastasis to the pituitary gland during clinical follow-up.

Conclusion

Incidental pituitary FDG uptake was a very rare finding. Cases with incidental pituitary FDG uptake were diagnosed primarily with clinically non-functioning adenomas, and there were also a few functioning adenomas. Further evaluations, including hormone assays and pituitary MRI, are warranted when pituitary uptake is found on FDG PET/CT.     

Value of<Superscript> 18</Superscript>F-FDG PET in the detection of peritoneal carcinomatosis

Purpose Peritoneal carcinomatosis can be difficult to diagnose using computed tomography (CT). The purpose of this study was to evaluate the role of 2-(fluorine 18) fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in the detection of peritoneal carcinomatosis.Methods We reviewed the CT and FDG PET radiological reports and clinical charts of 18 patients with peritoneal carcinomatosis and 17 cancer patients without peritoneal carcinomatosis. We also assessed FDG PET scans from 20 healthy volunteers as a baseline study. The maximum standardised uptake values (SUV_max) over peritoneal lesions in cancer patients and over the area of most intense intestinal uptake in healthy volunteers and cancer patients without peritoneal carcinomatosis were measured.Results The sensitivity and positive predictive value (PPV) of combined FDG PET and CT were superior to those of CT alone for the detection of peritoneal lesions (sensitivity: 66.7% vs 22.2%, p<0.025; PPV: 92.3% vs 50.0%, p<0.05). The most frequent pattern of FDG uptake in patients with peritoneal carcinomatosis was abnormally intense focal uptake near the abdominal wall. An SUV_max threshold of 5.1 produced a diagnostic accuracy of combined FDG PET and CT of 78%. The additional information provided by FDG PET allowed a more accurate diagnosis in 14 patients (40.0%), and led to alteration of the therapeutic strategy in five (14.3%) of the enrolled cancer patients.Conclusion We found that use of an intra-abdominal FDG uptake cut-off value for SUV_max of >5.1 assists in the diagnosis of peritoneal carcinomatosis. FDG PET may play an important role in the clinical management of patients with suspected peritoneal carcinomatosis.     

Quantification accuracy of neuro-oncology PET data as a function of emission scan duration in PET/MR compared to PET/CT

ObjectivesTo evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging.MethodsTwenty min ¹⁸F-FDG phantom measurements and 10 min ¹⁸F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n = 8) and a Biograph mMR PET/MR (n = 16). Listmode data were repeatedly split into frames of 1 min to 10 min length and reconstructed using two different reconstruction settings of a 3D-OSEM algorithm: with post-filtering (“OSEM”), and without post-filtering but with resolution recovery (“PSF”). Recovery coefficients (RC_max, RC_A50) and standard uptake values (SUV_max, SUV_A50) were evaluated.ResultsRC_max (phantom) and SUV_max (patients) increased significantly when reducing the frame duration. Significantly lower deviations were observed for RC_A50 and SUV_A50, respectively, making them more appropriate to compare PET studies at different number of counts. No statistical significant differences were observed when using post-filtering and reducing the frame time to 4 min (RC_A50, reference 20 min, phantom) and to 3 min (SUV_A50, reference 10 min, patients).ConclusionsFor hybrid aminoacid brain imaging, frame duration (or injected activity) can potentially be reduced to 30% of the standard used in clinical routine without significant changes on the quantification accuracy of the PET images if adequate reconstruction settings and quantitative measures are used. Frame times below 4 min in the NEMA phantom are not advisable to obtain quantitative and reproducible measures.     

Adrenal masses: the value of additional fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in differentiating between benign and malignant lesions

Objective  To investigate whether integrated fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) can differentiate benign from adrenal malignant lesions on the basis of maximum standardized uptake value (SUV_max), tumor/liver (T/L) SUV_max ratio, and CT attenuation value (Hounsfield Units; HU) of unenhanced CT obtained from FDG-PET/CT data. Methods  We studied 30 patients with 35 adrenal lesions (16 adrenal benign lesions, size 16 ± 5 mm, in 15 patients; and 19 adrenal malignant lesions, 24 ± 12 mm, in 15 patients) who had confirmed primary malignancies (lung cancer in 23 patients, lymphoma in 2, esophageal cancer in 2, hypopharyngeal cancer in 1, prostate cancer in 1, and 1 patient in whom lesions were detected at cancer screening). All patients underwent PET/CT at 1 h post FDG injection. Diagnosis of adrenal malignant lesions was based on interval growth or reduction after chemotherapy. An adrenal mass that remained unchanged for over 1 year was the standard used to diagnose adrenal benign lesions. Values of FDG uptake and CT attenuation were measured by placing volumetric regions of interest over PET/CT images. Adrenal uptake of SUV_max ≥ 2.5 was considered to indicate a malignant lesion; SUV_max < 2.5 was considered to indicate a benign lesion. In further analysis, 1.8 was employed as the threshold for the T/L SUV_max ratio. Unenhanced CT obtained from PET/CT data was considered positive for adrenal malignant lesions based on a CT attenuation value ≥ 10 HU; lesions with a value < 10 HU were considered adrenal benign lesions. Mann–Whitney’s U test was used for statistical analyses. Results  SUV_max in adrenal malignant lesions (7.4 ± 3.5) was higher than that in adrenal benign lesions (2.1 ± 0.5, p < 0.05). The CT attenuation value of adrenal malignant lesions (27.6 ± 11.9 HU) was higher than that of adrenal benign lesions (10.1 ± 12.3 HU, p < 0.05). In differentiating between adrenal benign and malignant lesions, a CT threshold of 10 HU corresponded to a sensitivity of 57%, specificity of 94%, accuracy of 74%, positive predictive value of 92% and negative predictive value of 65%. An SUV_max cut-off value of 2.5 corresponded to a sensitivity of 89%, specificity of 94%, accuracy of 91%, positive predictive value of 94% and negative predictive value of 88%. The T/L SUV_max ratio was 1.0 ± 0.2 for adrenal benign lesions and 4.5 ± 3.0 for adrenal malignant lesions. And T/L SUV_max ratio cut-off value of 1.8 corresponded to a sensitivity of 85%, specificity of 100%, accuracy of 91%, positive predictive value of 100% and negative predictive value of 83%. Conclusions  FDG-PET/CT with additional SUV_max analysis improves the diagnostic accuracy of adrenal lesions in cancer patients.     

Steroid responsive inflammatory myofibroblastic tumor of the lung evaluated by FDG PET/CT imaging

A 68-year-old gentleman was referred for ¹⁸F-FDG PET/CT for a pulmonary mass in the left upper lobe which demonstrated intensely FDG-avid confluent pulmonary consolidation in the left upper lobe (SUV_max 15.1). Histopathologic biopsy of the left upper lobe lung mass was consistent with inflammatory myofibroblastic tumor (IMT). The patient was started on steroid treatment in conjunction with antibiotics. Follow-up FDG PET/CT 3 weeks after commence of treatment showed remarkable response of the IMTs to therapy with much less avid FDG uptake (SUV_max 5.4) and marked improvement in the pulmonary consolidation. Nevertheless, the patient underwent left upper lobe lobectomy due to evidence of persistent cystic disease and malignant potential associated with IMTs. Final histopathology was consistent with IMT with no evidence of malignancy.     

Lesion-based detection of early chemosensitivity using serial static FDG PET/CT in metastatic colorectal cancer

Purpose

Medical oncology needs early identification of patients that are not responding to systemic therapy. ¹⁸F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) performed before and early during treatment has been proposed for this purpose. However, the best way to assess the change in FDG uptake between two scans has not been identified. We studied cutoff thresholds to identify responding tumours as a function of the method used to measure tumour uptake.

Methods

The study included 28 metastatic colorectal cancer (mCRC) patients who underwent 2 FDG PET/CT scans (baseline and at day 14 of the first course of polychemotherapy). For 78 tumour lesions, 4 standardized uptake value (SUV) indices were measured: maximum SUV (SUV_max) and mean SUV in a region obtained using an isocontour (SUV_40?%), with each of these SUV normalized either by the patient body weight (BW) or body surface area (BSA). The per cent change and absolute change in tumour uptake between the baseline and the early PET scans were measured based on these four indices. These changes were correlated to the RECIST 1.0-based response using contrast-enhanced CT at baseline and at 6–8?weeks on treatment.

Results

The 78 tumours were classified as non-responding (NRL, n?=?58) and responding lesions (RL, n?=?20). Receiver-operating characteristic (ROC) curves characterizing the performance in NRL/RL classification using early FDG PET uptake had areas under the curve between 0.75 and 0.84, without significant difference between the indices. The cutoff threshold in FDG uptake per cent change to get a 95?% sensitivity of RL detection depended on the way uptake was measured: ?14?% (specificity of 53?%) and ?22?% (specificity of 64?%) for SUV_max and SUV_40?%, respectively. Thresholds expressed as absolute SUV decrease instead of per cent change were less sensitive to the SUV definition: an SUV decline by 1.2 yielded a sensitivity of RL detection of 95?% for SUV_max and SUV_40?%. For a given cutoff threshold, the sensitivity was the same whatever the normalization (by BSA or BW).

Conclusion

A 14?% drop of tumour FDG SUV_max, 22?% drop of SUV_40?% or 1.2 drop of SUV_max or SUV_mean after one single course of polychemotherapy predicts objective response in mCRC lesions with a high sensitivity, potentially allowing the early identification of non-responding patients.     

Correlation of Primary Tumor FDG Uptake with Histopathologic Features of Advanced Gastric Cancer

Purpose

Histopathologic features could affect the FDG uptake of primary gastric cancer and detection rate on FDG PET/CT. The aim of this study was to evaluate the FDG uptake of primary gastric cancer by correlating it with the histopathologic features of the tumors.

Methods

Fifty patients with locally advanced gastric adenocarcinoma who were referred for preoperative FDG-PET/CT scans were enrolled in this study. The detection rate of PET/CT and maximum standardized uptake values (SUV_max) of the primary tumor were compared using the WHO, Lauren, Ming and Borrmann classifications and tumor size and location.

Results

In 45 of the 50 patients (90 %), the primary gastric tumors were detected by FDG PET/CT. On comparison using the WHO classification, the detection rate and SUV_max of the tubular type were significantly higher than those of the poorly cohesive type. On comparison using the Lauren and Ming classifications, the SUV_maxs of the intestinal type and expanding type were significantly higher than those of the diffuse and infiltrative type, respectively. On comparison using the Borrmann classification and tumor size and location, there was no significant difference in the detection rate and SUV_max of primary gastric tumors.

Conclusion

This study demonstrates that the poorly cohesive type according to the WHO classification, diffuse type according to the Lauren classification and infiltrative type according to the Ming classification have low FDG uptake in patients with locally advanced gastric carcinoma. Understanding the relationship between primary tumor FDG uptake and histopathologic features would be helpful in detecting the primary tumor by FDG PET/CT in patients with gastric cancer.     

Impact of blood glucose,diabetes, insulin,and obesity on standardized uptake values in tumors and healthy organs on 18F-FDG PET/CT

IntroductionChronically altered glucose metabolism interferes with ¹⁸F-FDG uptake in malignant tissue and healthy organs and may therefore lower tumor detection in ¹⁸F-FDG PET/CT. The present study assesses the impact of elevated blood glucose levels (BGL), diabetes, insulin treatment, and obesity on ¹⁸F-FDG uptake in tumors and biodistribution in normal organ tissues.Methods¹⁸F-FDG PET/CT was analyzed in 90 patients with BGL ranging from 50 to 372 mg/dl. Of those, 29 patients were diabetic and 21 patients had received insulin prior to PET/CT; 28 patients were obese with a body mass index > 25. The maximum standardized uptake value (SUV_max) of normal organs and the main tumor site was measured. Differences in SUV_max in patients with and without elevated BGLs, diabetes, insulin treatment, and obesity were compared and analyzed for statistical significance.ResultsIncreased BGLs were associated with decreased cerebral FDG uptake and increased uptake in skeletal muscle. Diabetes and insulin diminished this effect, whereas obesity slightly enhanced the outcome. Diabetes and insulin also increased the average SUV_max in muscle cells and fat, whereas the mean cerebral SUV_max was reduced. Obesity decreased tracer uptake in several healthy organs by up to 30%. Tumoral uptake was not significantly influenced by BGL, diabetes, insulin, or obesity.ConclusionsChanges in BGLs, diabetes, insulin, and obesity affect the FDG biodistribution in muscular tissue and the brain. Although tumoral uptake is not significantly impaired, these findings may influence the tumor detection rate and are therefore essential for diagnosis and follow-up of malignant diseases.     

18F-FDG PET/CT is a valuable tool for relapsing polychondritis diagnose and therapeutic response monitoring

Objectives

To retrospectively investigate the role of ¹⁸ F–fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for the diagnosis and therapeutic response in relapsing polychondritis (RP) patients.

Methods

¹⁸F-FDG PET/CT findings were reviewed in six RP patients. The initial scans were performed for all patients, follow-up scans were performed during steroid therapy for five patients. Changes in the abnormal lesions and the maximal standard uptake value (SUV_max) were analyzed.

Results

The initial PET/CT scans revealed intense FDG uptake in the cartilages for all six patients. The lesions of abnormal FDG uptake were tracheal/bronchial cartilage (n = 4), costicartilage (n = 4), nasal cartilage (n = 3), cricoid cartilage (n = 3), auricular cartilage (n = 3), arytenoid cartilage (n = 3), thyroid cartilage (n = 2), hyoid cartilage (n = 1) and mediastinum lymph node (n = 1). The mean visual score and the mean SUV_max were 2.96 ± 0.20 and 4.10 ± 0.6. The intense uptake reduced or disappeared during steroid therapy for five patients, the mean visual score and the mean SUV_max were 1.58 ± 1.4 and 1.51 ± 1.4.

Conclusions

¹⁸F-FDG PET/CT enables the acquisition of both morphologic and glucose metabolic of the related cartilage structures. It plays a valuable role in assessing almost all cartilage and detecting RP, which is a better selection of a biopsy site as well as therapeutic response monitoring.     

Comparison of 3′-deoxy-3′-[18F]fluorothymidine positron emission tomography (FLT PET) and FDG PET/CT for the detection and characterization of pancreatic tumours

Purpose

Despite recent advances in clinical imaging modalities, differentiation of pancreatic masses remains difficult. Here, we tested the diagnostic accuracy of molecular-based imaging including 3′-deoxy-3′-[¹⁸F]fluorothymidine (FLT) positron emission tomography (PET) and [¹⁸F]fluorodeoxyglucose (FDG) PET/CT in patients with suspected pancreatic masses scheduled to undergo surgery.

Methods

A total of 46 patients with pancreatic tumours suspicious for malignancy and scheduled for resective surgery were recruited prospectively. In 41 patients, FLT PET and FDG PET/CT scans were performed. A diagnostic CT performed on a routine basis was available in 31 patients. FLT PET and FDG PET/CT emission images were acquired according to standard protocols. Tracer uptake in the tumour [FDG and FLT standardized uptake value (SUV)] was quantified by the region of interest (ROI) technique. For FDG PET/CT analysis, correct ROI placement was ensured via side-by-side reading of corresponding CT images.

Results

Of 41 patients, 33 had malignancy, whereas 8 patients had benign disease. Visual analysis of FDG and FLT PET resulted in sensitivity values of 91% (30/33) and 70% (23/33), respectively. Corresponding specificities were 50% (4/8) for FDG PET and 75% (6/8) for FLT PET. In the subgroup of patients with contrast-enhanced CT (n?=?31), sensitivities were 96% (PET/CT), 88% (CT alone), 92% (FDG PET) and 72% (FLT PET), respectively. Mean FLT uptake in all malignant tumours was 3.0 (range SUV_max 1.1–6.5; mean FDG SUV_max 7.9, range 3.3–17.8; p?Conclusion For differentiation of pancreatic tumours, FDG PET and FDG PET/CT showed a higher sensitivity but lower specificity than FLT PET. Interestingly, visual analysis of FLT PET led to two false-positive findings by misinterpreting physiological bowel uptake as pathological FLT uptake in the pancreas. Due to the limited number of patients, the clinical value of adding FLT PET to the diagnostic workup of pancreatic tumours remains to be determined.     

Risk stratification and prediction of cancer of focal thyroid fluorodeoxyglucose uptake during cancer evaluation

Background  

Focal thyroid incidentaloma by F-18 2-deoxy-2-F18-fluoro-d-glucose (FDG) positron emission tomography (PET) has been reported 1–4% of cancer patients and normal healthy population, with a risk of cancer ranging 14–50%. The aim of this study was to investigate the prevalence of thyroid incidentaloma in F-18 FDG PET/CT and risk of cancer, usefulness of visual and SUV_max and SUV_mean differentiating malignant nodules and to define the predictable variables.     

Evaluation of Bone Metastasis from Hepatocellular Carcinoma Using 18F-FDG PET/CT and 99mTc-HDP Bone Scintigraphy: Characteristics of Soft Tissue Formation

Purpose

Bone metastasis from hepatocellular carcinoma (HCC) can present with soft tissue formation, resulting in oncologic emergency. Contrast-enhanced FDG PET/CT and bone scintigraphy were compared to evaluate characteristics of bone metastases with or without soft tissue formation from HCC.

Methods

Of 4,151 patients with HCC, 263 patients had bone metastases. Eighty-five patients with bone metastasis from HCC underwent contrast-enhanced FDG PET/CT. Fifty-four of the enrolled subjects had recent ^99mTc-HDP bone scintigraphy available for comparison. Metastatic bone lesions were identified with visual inspection on FDG PET/CT, and maximum standardized uptake value (SUV_max) was used for the quantitative analysis. Confirmation of bone metastasis was based on histopathology, combined imaging modalities, or serial follow-up studies.

Results

Forty-seven patients (55%) presented with soft tissue formation, while the remaining 38 patients presented without soft tissue formation. Frequent sites of bone metastases from HCC were the spine (39%), pelvis (19%), and rib cage (14%). The soft-tissue-formation group had more frequent bone pain (77 vs. 37%, p < 0.0001), higher SUV_max (6.02 vs. 3.52, p < 0.007), and higher incidence of photon defect in bone scintigraphy (75 vs. 0%) compared to the non-soft-tissue-formation group. FDG PET/CT had higher detection rate for bone metastasis than bone scintigraphy both in lesion-based analysis (98 vs. 53%, p = 0.0015) and in patient-based analysis (100 vs. 80%, p < 0 .001).

Conclusions

Bone metastasis from HCC showed a high incidence of soft tissue formation requiring emergency treatment. Although the characteristic findings for soft tissue formation such as photon defect in bone scintigraphy are helpful in detection, overall detectability of bone metastasis is higher in FDG PET/CT. Contrast-enhanced PET/CT will be useful in finding and delineating soft-tissue-forming bone metastasis from HCC.     

Predictive role of post-treatment [18F]FDG PET/CT in patients with uterine cervical cancer

Objective

To evaluate the efficacy of post-treatment positron emission tomography (PET)/computed tomography (CT) for identification of tumor recurrence, and to determine whether [¹⁸F]fluorodeoxyglucose (FDG) uptake measured as the maximum standardized uptake value (SUV_max) has predictive role regarding survival in patients with uterine cervical cancer.

Methods

Medical records from 276 women with uterine cervical cancer who had post-treatment [¹⁸F]FDG PET/CT performed were retrospectively reviewed. Results of PET/CT scans were compared with histological or clinical examination.

Results

Ninety-five (34.4%) of the 276 patients had documented recurrence by either surgical biopsy or clinical and imaging follow-up. Median duration from treatment to PET/CT scan was 24 months (range, 6–307). The overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of post-treatment PET/CT were 94.7%, 87.8%, 80.4%, 97%, and 90.2%, respectively. The PET/CT scan modified both the diagnostic or treatment plan in 67 patients (24.3%). Patients were divided into two groups according to cut-off SUV_max established on the basis of ROC analysis (<5.25 vs. ≥5.25), and there was a significant difference in OS between groups (p = 0.001). In addition, the 5-year progression-free survival (PFS) and OS rates of patients with a negative PET/CT scan for recurrence were significantly better than those with a positive PET/CT (98.62% vs. 17.83%, p < 0.0001 for PFS, 99.31% vs. 85.38%, p = 0.0015 for OS).

Conclusion

Post-treatment PET/CT scan is a sensitive and accurate surveillance modality, and provides prognostic information in uterine cervical cancer. Furthermore, it may allow individualization of patient care.     

The impact of systemic chemotherapy on testicular FDG activity in young men with Hodgkin’s lymphoma

Purpose

Based on prior reports suggesting a positive correlation between fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)/CT and total sperm count and concentration, we sought to identify changes in testicular FDG uptake over the course of chemotherapy in young men with Hodgkin’s lymphoma.

Methods

Fifty-two patients with a mean age of 24.2 years (range 15.5–44.4) at diagnosis monitored with FDG PET/CT to assess treatment response for Hodgkin’s lymphoma were selected for this retrospective analysis under an Institutional Review Board waiver. Of the patients, 26 were treated with a chemotherapy regimen known to cause prolonged and sometimes permanent azoospermia (BEACOPP—bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone) and 26 with a regimen known to have a much milder effect on gonadal function (ABVD—doxorubicin, bleomycin, vincristine, and dacarbazine). Each patient underwent one FDG PET/CT before treatment and at least one FDG PET/CT after start of chemotherapy. In all examinations, FDG activity was measured in the testes with different quantification metrics: maximum standardized uptake value (SUV_max), SUV_mean, functional volume (FV) and total testicular glycolysis (TTG), and blood pool activity determined (SUV_mean).

Results

Testicular FDG uptake (SUV_max) was significantly associated with blood pool activity (p?<?0.001). Furthermore, testicular FDG uptake metrics incorporating volume (e.g., FV and TTG) were associated with age. There was no significant change in SUV_max, SUV_mean, FV, and TTG from the PET/CT at baseline to the PET/CTs over the course of chemotherapy either for patients treated with BEACOPP or for patients treated with ABVD.

Conclusion

For patients undergoing chemotherapy for Hodgkin’s lymphoma, there is a significant association between testicular FDG uptake and blood pool activity, but no significant changes in FDG uptake over the course of chemotherapy. Therefore, FDG uptake may not be a feasible surrogate marker for fertility monitoring in patients with Hodgkin’s lymphoma undergoing chemotherapy.