Standardized added metabolic activity (SAM) IN 18F-FDG PET assessment of treatment response in colorectal liver metastases

Purpose

Standardized added metabolic activity (SAM) is a PET parameter for assessing the total metabolic load of malignant processes, avoiding partial volume effects and lesion segmentation. The potential role of this parameter in the assessment of response to chemotherapy and bevacizumab was tested in patients with metastatic colorectal cancer with potentially resectable liver metastases (mCRC).

Methods

¹⁸F-FDG PET/CT was performed in 18 mCRC patients with liver metastases before treatment and after five cycles of FOLFOX/FOLFIRI and bevacizumab. Of the 18 patients, 16 subsequently underwent resection of liver metastases. Baseline and follow-up SUV_max, and SAM as well as reduction in SUV_max (?SUV_max) and SAM (?SAM) of all liver metastases were correlated with morphological response, and progression-free and overall survival (PFS and OS).

Results

A significant reduction in metabolic activity of the liver metastases was seen after chemotherapy with a median ?SUV_max of 25.3 % and ?SAM of 94.5 % (p?=?0.033 and 0.003). Median baseline SUV_max and SAM values were significantly different between morphological responders and nonresponders (3.8 vs. 7.2, p?=?0.021; and 34 vs. 211, p?=?0.002, respectively), but neither baseline PET parameters nor morphological response was correlated with PFS or OS. Follow-up SUV_max and SAM as well as ?SAM were found to be prognostic factors. The median PFS and OS in the patient group with a high follow-up SUV_max were 10.4 months and 32 months, compared to a median PFS of 14.7 months and a median OS which had not been reached in the group with a low follow-up SUV_max (p?=?0.01 and 0.003, respectively). The patient group with a high follow-up SAM and a low ?SAM had a median PFS and OS of 9.4 months and 32 months, whereas the other group had a median PFS of 14.7 months and a median OS which had not been reached (p?=?0.002 for both PFS and OS).

Conclusion

¹⁸F-FDG PET imaging is a useful tool to assess treatment response and predict clinical outcome in patients with mCRC who undergo chemotherapy before liver metastasectomy. Follow-up SUV_max, follow-up SAM and ?SAM were found to be significant prognostic factors for PFS and OS.     

Prediction of outcome in pediatric Hodgkin lymphoma based on interpretation of <Superscript>18</Superscript>FDG-PET/CT according to ΔSUV<Subscript>max</Subscript>, Deauville 5-point scale and IHP criteria

Objective

Minimizing side effects by using response-adopted therapy strategies plays an important role in the management of pediatric Hodgkin lymphoma (HL); however, the criteria for the definition of adequate or inadequate response are controversial. The aim of this study is to compare different methods of interpretation of ¹⁸F-FDG-PET/CT (PET) in the prediction of disease outcome in order to determine the optimum method in this regard.

Methods

Baseline, interim and post-treatment PET scans of 72 children were interpreted according to revised International Harmonization Project criteria (IHP) and Deauville criteria. Cut-off values for changes in interim and post-treatment FDG uptake (ΔSUV_max) in the prediction of progression-free survival (PFS) were measured using ROC analysis. Quantitative and visual data were compared with each other in the prediction of PFS.

Results

Mean interim and post-treatment ΔSUV_max of the primary lesions were 77.4 ± 19.5 and 68.8 ± 30.4% and respective cut-off values were 82 and 73%. However, only post-treatment ΔSUV_max yielded statistically significant results in the prediction of 3-year PFS (p = 0.043). Interim ΔSUV_max was further analyzed according to the values reported in the literature (66 and 77%) yet statistically significant results were not reached (p = 0.604 and 0.431). For interim evaluation, IHP criteria was correlated to Deauville criteria (p = 0.002 and p = 0.001) and ΔSUV_max (p = 0.03), whereas for post-treatment evaluation, significant correlation with ΔSUV_max (p = 0.04) but marginally significant (p = 0.055 and p = 0.058) correlation with Deauville criteria were achieved. Overall, 1, 3 and 5-year PFS were 95.7 ± 0.2, 89.6 ± 0.4 and 80.8 ± 0.7%, respectively. All methods demonstrated comparable performance in the prediction of 3-year PFS; however, interim PET using Deauville criteria and post-treatment PET using IHP criteria were statistically significant. All methods demonstrated high negative-predictive value but substantially low positive-predictive value.

Conclusions

Deauville criteria are superior to other methods in the prediction of pediatric HL outcome using interim PET data. On the other hand, quantitative evaluation and visual evaluation by IHP can be used reliably at the end of the treatment. In this regard, we report the optimal cut-off value of SUV_max reduction as 73%.

     

Different predictive values of interim <Superscript>18</Superscript>F-FDG PET/CT in germinal center like and non-germinal center like diffuse large B-cell lymphoma

Purpose

Diffuse large B-cell lymphoma (DLBCL) is a pathologically heterogeneous disease with different prognoses according to its molecular profiles. Despite the broad usage of ¹⁸F-fluoro-2-dexoxy-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT), previous studies that have investigated the value of interim ¹⁸F-FDG PET/CT in DLBCL have given the controversial results. The purpose of this study was to evaluate the prognostic value of interim ¹⁸F-FDG PET/CT in DLBCL according to germinal center B cell-like (GCB) and non-GCB molecular profiling.

Methods

We enrolled 118 newly diagnosed DLBCL patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). Interim ¹⁸F-FDG PET/CT scans performed after 2 or 3 cycles of R-CHOP treatment were evaluated based on the Lugano response criteria. Patients were grouped as GCB or non-GCB molecular subtypes according to immunohistochemistry results of CD10, BCL6, and MUM1, based on Hans’ algorithm.

Results

In total 118 DLBCL patients, 35 % were classified as GCB, and 65 % were classified as non-GCB. Interim PET/CT was negative in 70 %, and positive in 30 %. During the median follow-up period of 23 months, the positive interim ¹⁸F-FDG PET/CT group showed significantly inferior progression free survival (PFS) compared to the negative interim ¹⁸F-FDG PET/CT group (P = 0.0004) in entire patients. A subgroup analysis according to molecular profiling demonstrated significant difference of PFS between the positive and negative interim ¹⁸F-FDG PET groups in GCB subtype of DLBCL (P = 0.0001), but there was no significant difference of PFS between the positive and negative interim ¹⁸F-FDG PET groups in non-GCB subtype of DLBCL.

Conclusions

Interim ¹⁸F-FDG PET/CT scanning had a significant predictive value for disease progression in patients with the GCB subtype of DLBCL treated with R-CHOP, but not in those with the non-GCB subtype. Therefore, molecular profiles of DLBCL should be considered for interim ¹⁸F-FDG PET/CT practice.

     

Prognostic relevance of 18F-FDG PET uptake in patients with locally advanced,extremity soft tissue sarcomas undergoing neoadjuvant isolated limb perfusion with TNF-α and melphalan

Purpose

The objective of this study was to determine whether ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can adequately assess the risk of systemic disease progression in patients with primary, localized, high-grade soft tissue sarcomas of the extremities undergoing neoadjuvant isolated limb perfusion (ILP) with tumour necrosis factor and melphalan.

Methods

This was a retrospective analysis of the files of 35 patients who underwent a PET or PET/CT scan prior to and after ILP followed by surgical resection with curative intent between 2006 and 2012. SUV_max1 was defined as the maximum standardized uptake value (SUV) at diagnosis, SUV_max2 as the maximum SUV after ILP and ΔSUV_max as the percentage difference between SUV_max1 and SUV_max2.

Results

The median follow-up was 40 months for all patients. The median SUV_max1 amounted to 7.6, while the median SUV_max2 was 4.7. The median ΔSUV_max was ?44 %. Overall survival (OS) probability at 2 and 5 years amounted to 78 and 70 %, respectively, while metastasis-free survival (MFS) probability at 2 and 5 years was 67 and 64 %, respectively. Receiver-operating characteristic (ROC) curve analysis showed that both SUV_max2 and ΔSUV_max could predict systemic disease progression, while SUV_max1 could not adequately identify patients who went on to develop metastatic disease. The optimal cut-off value was 6.9 for SUV_max2 and ?31 % for ΔSUV_max. Patients with an SUV_max2 <6.9 had a 2-year MFS of 80 %, compared to 31 % for patients with an SUV_max2?≥?6.9 (p?<?0.001). Patients with a ΔSUV_max?<??31 %, i.e. patients with a higher metabolic response, had an MFS of 76 % at 2 years, compared to 42 % for patients with a ΔSUV_max?≥??31 % (p?=?0.050).

Conclusion

SUV_max after ILP for primary, locally advanced, non-metastatic high-grade soft tissue sarcomas of the extremities appears to be significantly correlated with prognosis. Whether patients with a high SUV_max after ILP will benefit from standard or experimental adjuvant systemic treatment options should be evaluated in future studies.     

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.

     

Anatomical and functional volume concordance between FDG PET,and T2 and diffusion-weighted MRI for cervical cancer: a hybrid PET/MR study

Purpose

To evaluate the concordance among ¹⁸F-FDG PET imaging, MR T2-weighted (T2-W) imaging and apparent diffusion coefficient (ADC) maps with diffusion-weighted (DW) imaging in cervical cancer using hybrid whole-body PET/MR.

Methods

This study prospectively included 35 patients with cervical cancer who underwent pretreatment ¹⁸F-FDG PET/MR imaging. ¹⁸F-FDG PET and MR images were fused using standard software. The percent of the maximum standardized uptake values (SUV_max) was used to contour tumours on PET images, and volumes were calculated automatically. Tumour volumes measured on T2-W and DW images were calculated with standard techniques of tumour area multiplied by the slice profile. Parametric statistics were used for data analysis.

Results

FDG PET tumour volumes calculated using SUV_max (14.30?±?4.70) and T2-W imaging volume (33.81?±?27.32 cm³) were similar (P?>?0.05) at 35 % and 40 % of SUV_max (32.91?±?18.90 cm³ and 27.56?±?17.19 cm³ respectively) and significantly correlated (P?<?0.001; r?=?0.735 and 0.766). The mean DW volume was 30.48?±?22.41 cm³. DW volumes were not significantly different from FDG PET volumes at either 35 % SUV_max or 40 % SUV_max or from T2-W imaging volumes (P?>?0.05). PET subvolumes with increasing SUV_max cut-off percentage showed an inverse change in mean ADC values on DW imaging (P?<?0.001, ANOVA).

Conclusion

Hybrid PET/MR showed strong volume concordance between FDG PET, and T2-W and DW imaging in cervical cancer. Cut-off at 35 % or 40 % of SUV_max is recommended for ¹⁸F-FDG PET/MR SUV-based tumour volume estimation. The linear tumour subvolume concordance between FDG PET and DW imaging demonstrates individual regional concordance of metabolic activity and cell density.     

Positron-emission tomography CT to identify local recurrence in stage I lung cancer patients 1 year after stereotactic body radiation therapy

Purpose

To evaluate the diagnostic value of positron-emission tomography/computed tomography (PET/CT) in stage I lung cancer patients treated with stereotactic body radiation therapy (SBRT), who have suspicious or unclear local recurrence findings in CT 1 year after treatment.

Patients and methods

A group of 29 patients with unclear or suspicious CT findings 1 year after SBRT were examined with PET/CT. The ability of standard uptake values (SUV_max, SUV_mean and posttherapeutic reduction in SUV) to detect local failure and identify patients at a high risk of disease-specific death was evaluated using logrank statistics. Histology and clinical follow-up were the gold standards for local recurrence.

Results

SUV_mean greater than 3.44 (p?=?0.001); SUV_max greater than 5.48 (p?=?0.009) or a relative reduction in SUV_mean or SUV_max of less than 43 (p?=?0.030) or 52?% (p?=?0.025), respectively, was indicative of local recurrence. These parameters also correlated with an increased risk of disease-specific death: SUV_mean greater than 2.81 (p?=?0.023); SUV_max greater than 3.45 (p?=?0.007) or a relative reduction in SUV_mean or SUV_max of less than 32 (p?=?0.015) or 52?% (p?=?0.013), respectively, was indicative of an increased risk of disease-specific death.

Conclusion

PET/CT performed 1 year after SBRT can reliably identify local recurrence and therefore help to clarify unclear CT findings. As posttherapeutic glucose metabolism also correlates with disease-specific survival, PET/CT may help to stratify lung cancer patients for additional treatment 1 year after SBRT.     

An international confirmatory study of the prognostic value of early PET/CT in diffuse large B-cell lymphoma: comparison between Deauville criteria and ΔSUVmax

Purpose

The role of interim PET/CT in guiding therapeutic strategies in diffuse large B-cell lymphoma (DLBCL) is debated, mainly because interpretation rules vary among centres. This study aimed to explore the reproducibility and confirm the prognostic value of early PET/CT using the Deauville criteria and ΔSUVmax.

Methods

This international confirmatory study retrospectively evaluated 114 patients with newly diagnosed DLBCL treated with a rituximab-containing regimen. All patients underwent ¹⁸F-FDG PET/CT at baseline (PET0) and after two cycles (PET2), with no therapy change based on the latter. Scans were interpreted by three observers using the Deauville five-point scale and ΔSUVmax between PET0 and PET2 was calculated. Interpretations were evaluated for interobserver agreement and for progression-free survival (PFS) prediction.

Results

Median follow-up was 39 months. Early PET/CT was predictive of outcome when interpreted with the Deauville criteria and ΔSUVmax. Using the five-point scale, the overall kappa value was 0.66 with the reference background set in the liver (score ≥4) and interobserver agreement was even better using a 66 % ΔSUVmax cut-off (κ?=?0.83). Moreover, the prognostic value of interim PET was slightly inferior when using a Deauville score ≥4 than when using a 66 % ΔSUVmax cut-off: for the Deauville score the 3-year PFS estimate was 59 % (45–73 %) in PET2-positive patients vs. 81 % (71–91 %) in PET2-negative patients (P?=?0.003); for the 66 % ΔSUVmax cut-off the 3-year PFS estimate was 44 % (23–65 %) in PET2-positive patients vs. 79 % (70–88 %) in PET2-negative patients (P?=?0.0002).

Conclusion

Although the Deauville criteria are valid for assessing the prognostic value of early PET/CT in DLBCL, computation of the ΔSUVmax leads to better performance and interobserver reproducibility, and should be preferred when a baseline scan is available.     

Factors affecting intrapatient liver and mediastinal blood pool 18F-FDG standardized uptake value changes during ABVD chemotherapy in Hodgkin’s lymphoma

Purpose

The aim of our study was to assess the intrapatient variability of 2-deoxy-2-(¹⁸F)-fluoro-D-glucose (¹⁸F-FDG) uptake in the liver and in the mediastinum among patients with Hodgkin’s lymphoma (HL) treated with doxorubicin (Adriamycin), bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy (CHT).

Methods

The study included 68 patients (30 men, 38 women; mean age 32?±?11 years) with biopsy-proven HL. According to Ann Arbor criteria, 6 were stage I, 34 were stage II, 12 were stage 3 and 16 were stage 4. All of them underwent a baseline (PET0) and an interim (PET2) ¹⁸F-FDG whole-body positron emission tomography (PET)/CT. All patients were treated after PET0 with two ABVD cycles for 2 months that ended 15?±?5 days prior to the PET2 examination. All patients were further evaluated 15?±?6 days after four additional ABVD cycles (PET6). None of the patients presented a serum glucose level higher than 107 mg/dl. The mean and maximum standardized uptake values (SUV) of the liver and mediastinum were calculated using the same standard protocol for PET0, PET2 and PET6, respectively. Data were examined by means of the Wilcoxon matched pairs test and linear regression analysis.

Results

The main results of our study were an increased liver SUV_mean in PET2 (1.76?±?0.35) as compared with that of PET0 (1.57?±?0.31; p?<?0.0001) and PET6 (1.69?±?0.28; p?=?0.0407). The same results were obtained when considering liver SUV_max in PET2 (3.13?±?0.67) as compared with that of PET0 (2.82?±?0.64; p?<?0.0001) and PET6 (2.96?±?0.52; p?=?0.0105). No significant differences were obtained when comparing mediastinum SUV_mean and SUV_max in PET0, PET2 and PET6 (p?>?0.05). Another finding is a relationship in PET0 between liver SUV_mean and SUV_max with the stage, which was lower in those patients with advanced disease (r ²?=?0.1456 and p?=?0.0013 for SUV_mean and r ²?=?0.1277 and p?=?0.0028 for SUV_max).

Conclusion

The results of our study suggest that liver ¹⁸F-FDG uptake is variable in patients with HL during the CHT treatment and the disease course and should be considered carefully when used to define the response to therapy in the interim PET in HL.     

Metabolic response evaluated by 18F-FDG PET/CT as a potential screening tool in identifying a subgroup of patients with advanced non-small cell lung cancer for immediate maintenance therapy after first-line chemotherapy

Purpose

Among patients with advanced non-small cell lung cancer (NSCLC), identification of a subgroup of patients for immediate maintenance treatment after first-line chemotherapy has great importance in improving survival. The purpose of this study was to investigate whether the metabolic responses evaluated by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) may be a potential screening tool for identifying patients with early disease progression who may benefit from immediate maintenance treatment.

Methods

A total of 52 patients with advanced NSCLC (36 men and 16 women, mean age 57.2?±?10.6 years) who underwent baseline and follow-up ¹⁸F-FDG PET/CT after four cycles of first-line chemotherapy were enrolled. Maximum standardized uptake value (SUV_max), SUV_peak, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) of the tumour lesions were measured and percentage decrease of the parameters was calculated. The prognostic significance of percentage decrease of these parameters and other clinical variables related to progression-free survival (PFS) and overall survival (OS) were assessed by Cox proportional hazards regression analysis. Receiver-operating characteristic (ROC) curve analysis was used to define the optimal cut-off value of percentage decrease of the parameters that could distinguish between early (PFS?<?6 months) and late (PFS?≥?6 months) disease progression groups.

Results

Multivariate analysis showed that percentage decrease of TLG [hazard ratio per 10 % decrease?=?1.030, 95 % confidence interval (CI)?=?1.012–1.048, p?=?0.001) was a significant predictor of PFS and OS. ROC curves identified a 50.0 % decrease in TLG as the optimal cut-off value to distinguish disease progression groups. Positive and negative predictive values of the optimal TLG value for selecting patients with late disease progression were 36.4 and 100.0 %, respectively.

Conclusion

The percentage decrease in TLG of measurable tumour lesions may be a potential parameter to appropriately identify a subgroup of patients for immediate maintenance treatment after first-line chemotherapy in patients with advanced NSCLC.     

The value of 18F-FDG PET/CT in the management of malignant peripheral nerve sheath tumors

Purpose

Our objective was to determine how positron emission tomography (PET)/CT had been used in the clinical treatment of malignant peripheral nerve sheath tumor (MPNST) patients at The University of Texas MD Anderson Cancer Center.

Methods

We reviewed a database of MPNST patients referred to MD Anderson Cancer Center during 1995–2011. We enrolled 47 patients who underwent PET/CT imaging. Disease stage was based on conventional imaging and PET/CT findings using National Comprehensive Cancer Network (NCCN) guidelines. Treatment strategies based on PET/CT and conventional imaging were determined by chart review. The maximum and mean standardized uptake values (SUV_max, SUV_mean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), change in SUV_max, change in MTV, and change in TLG were calculated from the PET/CT studies before and after treatment. Response prediction was based on imaging studies performed before and after therapy and categorized as positive or negative for residual tumor. Clinical outcome was determined from chart review.

Results

PET/CT was performed for staging in 16 patients, for restaging in 29 patients, and for surveillance in 2 patients. Of the patients, 88 % were correctly staged with PET/CT, whereas 75 % were correctly staged with conventional imaging. The sensitivity to detect local recurrence and distant metastasis at restaging was 100 and 100 % for PET/CT compared to 86 and 83 % for conventional imaging, respectively. PET/CT findings resulted in treatment changes in 31 % (5/16) and 14 % (4/29) of patients at staging and restaging, respectively. Recurrence, MTV, and TLG were prognostic factors for survival, whereas SUV_max and SUV_mean were not predictive. For 21 patients who had imaging studies performed both before and after treatment, PET/CT was better at predicting outcome (overall survival, progression-free survival) than conventional imaging. A decreasing SUV_max ≥ 30 % and decrease in TLG and MTV were significant predictors for overall and progression-free survival.

Conclusion

PET/CT is valuable in MPNST management because of its high accuracy in staging and high sensitivity and accuracy in restaging as well as improvements in treatment planning. MTV from baseline staging studies is predictive of survival. Additionally, change in SUV_max, TLG, and MTV accurately predicted outcomes after treatment.     

SUV<Subscript>max</Subscript> on FDG-PET is a predictor of prognosis in patients with maxillary sinus cancer

Purpose

Our aim was to determine whether the maximum standardized uptake value (SUV_max) of the primary lesion demonstrated by [¹⁸F]-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is associated with the prognosis of maxillary sinus cancer.

Materials and methods

The relationships of clinicopathological factors including age, T stage, N stage, histologic type, treatment strategy, and primary tumor SUV_max with progression-free (PFS) and overall (OS) survival were evaluated using the log-rank test and Cox method in 31 patients with maxillary sinus cancer before combined superselective intra-arterial chemotherapy using high-dose cisplatin with concurrent radiotherapy, or radiotherapy alone.

Results

The median duration of follow-up was 55.4 (range 9.7–72.6) months. PFS and OS of patients exhibiting a high SUV_max (≥16 and ≥17, respectively) for the primary tumor were significantly lower than those of patients for whom the primary tumor SUV_max was low (p = 0.0010 and p = 0.033, respectively). Multivariate analyses showed that T stage (p = 0.0049) and primary tumor SUV_max (p = 0.026) were independently prognostic of poorer PFS and that only primary tumor SUV_max (p = 0.049) was independently prognostic of poorer OS.

Conclusion

SUV_max of the primary tumor determined by FDG-PET/CT before treatment could be a good surrogate marker for prognostication of maxillary sinus cancer.

     

Assessment of aortitis by semiquantitative analysis of 180-min 18F-FDG PET/CT acquisition images

Purpose

The aim of this study was to evaluate the contribution of semiquantitative analysis of 180-min ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT images for the assessment of aortitis in cases of suspected large vessel vasculitis (LVV) and to establish a threshold index for application in the clinical setting.

Methods

This prospective study included 43 patients (mean age 67.5?±?12.9?years) with suspicion of LVV (25 with a final diagnosis of aortitis). ¹⁸F-FDG PET/CT scan was acquired 180 min after injection of 7 MBq/kg of ¹⁸F-FDG. A semiquantitative analysis was performed calculating the aortic wall maximum standardized uptake value (SUV_max) (T), the lumen SUV_max (B) and the target to background ratio (TBR). These results were also compared with those obtained in a control population.

Results

The mean aortic wall SUV_max was 2.00?±?0.62 for patients with aortitis and 1.45?±?0.31 for patients without aortitis (p?p?max (0.997 vs 0.871). The highest sensitivity and specificity was obtained for a TBR of 1.34 (sensitivity 100 %, specificity 94.4 %).

Conclusion

Semiquantitative analysis of PET/CT images acquired 180 min after ¹⁸F-FDG injection and the TBR index of 1.34 show very high accuracy and, therefore, are strongly recommended for the diagnosis of aortitis in the clinical setting.     

Suppression of myocardial 18F-FDG uptake with a preparatory “Atkins-style” low-carbohydrate diet

Objectives

Physiological myocardial uptake of 18F-FDG during positron emission tomography can mask adjacent abnormal uptake in mediastinal malignancy and inflammatory cardiac diseases. Myocardial uptake is unpredictable and variable. This study evaluates the impact of a low-carbohydrate diet in reducing myocardial FDG uptake.

Method

Patients attending for clinically indicated oncological FDG PET were asked to have an “Atkins-style” low-carbohydrate diet (less than 3 g) the day before examination and an overnight fast. A total of 120 patients following low-carbohydrate diet plus overnight fast were compared with 120 patients prepared by overnight fast alone. Patients having an Atkins-style diet also completed a diet compliance questionnaire. SUV_max and SUV_mean for myocardium, blood pool and liver were measured in both groups.

Results

Myocardial SUV_max fell from 3.53?±?2.91 in controls to 1.77?±?0.91 in the diet-compliant group. 98 % of diet-compliant patients had a myocardial SUV_max less than 3.6 compared with 67 % of controls. Liver and blood pool SUV_max rose from 2.68?±?0.49 and 1.82?±?0.30 in the control group to 3.14?±?0.57 and 2.06?±?0.30.

Conclusion

An Atkins-style diet the day before PET, together with an overnight fast, effectively suppresses myocardial FDG uptake.

Key Points

? Low-carbohydrate diet (LCD) the day before PET suppresses myocardial FDG uptake. ? LCD before PET increases liver and blood pool SUV _max and SUV _mean . ? Suppression of myocardial uptake may improve PET imaging of thoracic disease. ? Suppression of myocardial uptake may help imaging cardiac inflammatory disease with PET.     

Prospective evaluation of solitary thyroid nodule on 18F-FDG PET/CT and high-resolution ultrasonography

Purpose

The utility of 18F-FDG PET/CT in the assessment of thyroid nodules is unclear as there are several conflicting reports on the usefulness of SUV as an indicator to distinguish benign from malignant thyroid lesions. This study incorporated an additional parameter, namely dual time point imaging, to determine the diagnostic accuracy of PET/CT imaging. The performance of 18F-FDG PET/CT was compared to that of high-resolution ultrasound which is routinely used for the evaluation of thyroid nodules.

Methods

Two hundred patients with incidentally detected solitary thyroid nodules were included in the study. Each patient underwent ultrasound and PET/CT evaluation within 7 days of each other, reported by an experienced radiologist and nuclear medicine specialist, respectively, in a blinded manner. The PET/CT criteria employed were maximum SUV (SUV_max) at 60 min and change in SUV_max at delayed (120 min) imaging. Final diagnosis was based on pathological evaluation and follow-up.

Results

Of the 200 patients, 26 had malignant and 174 had benign nodules. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of ultrasound were 80.8, 81.6, 39.6, 96.6 and 81.5%, respectively. Using SUV_max at 60 min as the diagnostic criterion, the above indices were 80.8, 84.5, 43.8, 96.7 and 84%, respectively, for PET/CT. The SUV_max of malignant thyroid lesions was significantly higher than benign lesions (16.2 ± 10.6 vs. 4.5 ± 3.1, respectively; p = 0.0001). Incorporation of percentage change in SUV_max at delayed imaging as the diagnostic criterion yielded a slightly improved sensitivity, specificity, PPV, NPV and accuracy of 84.6, 85.6, 46.8, 97.4 and 85.5%, respectively. There was a significant difference in percentage change in SUV_max between malignant and benign thyroid lesions (14.9 ± 11.4 vs. ?1.6 ± 13.7, respectively; p = 0.0001). However, there was no statistically significant difference (95% confidence interval) between the diagnostic performance of PET/CT and ultrasound.

Conclusions

Routine use of 18F-FDG PET/CT with SUV_max at 60 min as the sole diagnostic criterion does not appear to have a significant advantage over high-resolution ultrasound in the evaluation of thyroid nodules. Incorporation of dual time point imaging enhances image interpretation, and yields a higher diagnostic performance, yet it is not statistically significant. Bearing in mind the cost, limited availability and radiation exposure, routine use of 18F-FDG PET/CT for distinguishing benign from malignant thyroid nodules cannot be recommended.     

Prognostic value of volumetric FDG PET/CT parameters in patients with oral tongue squamous cell carcinoma who were treated by superselective intra-arterial chemoradiotherapy

Purpose

This study aimed to evaluate the predictive and prognostic value of FDG PET/CT-based volumetric parameters in patients with oral tongue squamous cell carcinoma (OTSCC) treated by superselective intra-arterial chemoradiotherapy (IA-CRT).

Methods

We conducted a retrospective study including 33 patients with biopsy-proven OTSCC between May 2007 and February 2016. All of the patients were treated by IA-CRT. Pretreatment SUV_max and metabolic tumor volume (MTV) of the primary tumor were measured. The SUV thresholds of 2.5 and 5.0 were used. Progression-free survival (PFS) and overall survival (OS) were chosen as endpoints to evaluate prognosis. Univariate and multivariate analyses were performed to assess the potential independent effect of FDG PET/CT parameters.

Results

The median follow-up for surviving patients was 40.7 months (range 6.0–107.5 months). In univariate and multivariate analyses, SUV_max and MTV (5.0) were independent prognostic factors for PFS. In univariate analysis, SUV_max failed to predict OS. MTV (5.0) was a significant prognostic factor for OS, but multivariate analysis failed to show statistical independence because it could not exclude the possibility of an artifact due to N stage.

Conclusions

FDG PET/CT-based volumetric parameters may be significant prognostic markers for survival of patients with OTSCC who are treated by IA-CRT.

     

The prognostic value of mid- and post-treatment [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in indolent follicular lymphoma

Background

[¹⁸F]fluorodeoxyglucose positron emission tomography (PET) is a useful staging investigation for follicular lymphoma (FL). Recent studies have shown that positive post-treatment PET is also a strong predictor of inferior overall survival.

Purpose

To evaluate the predictive value of mid- and post-treatment PET in FL patients with respect to progression-free survival (PFS) and overall survival (OS).

Methods

We included 57 patients with indolent FL (grade 1, 2, and 3a) who received induction chemotherapy. Mid- and post-treatment PET results were correlated with PFS and OS retrospectively and analysed using Kaplan–Meier survival analysis and Cox regression.

Results

Post-treatment PET was predictive of OS (mean OS 95.2 vs. 45.0 months for PET-negative vs. PET-positive, p < 0.001) and showed a trend towards significance for PFS (mean PFS 74.4 vs. 38.2 months for PET? vs. PET+, p = 0.083). 3-year PFS for post-treatment PET? and PET+ patients were 72 and 30 %, respectively. 3-year OS were 96 and 60 %, respectively. Mid-treatment PET was not predictive of PFS (mean PFS 78.5 vs. 51.0 months for PET? vs. PET+, p = 0.35) nor OS (mean OS 89.9 vs. 76.6 months for PET? vs. PET+, p = 0.92).

Conclusion

Post-treatment PET is predictive of OS in indolent FL. It identifies patients who might benefit from more intensive follow-up, enrolment in clinical trials or second-line therapy. Mid-treatment PET scan results did not appear to predict long-term treatment outcomes.     

Diagnostic accuracy of 68Ga-DOTANOC PET/CT imaging in pheochromocytoma

Purpose

The purpose of the present study was to evaluate the diagnostic accuracy of ⁶⁸Ga-DOTANOC positron emission tomography (PET)/CT in patients with suspicion of pheochromocytoma.

Methods

Data of 62 patients [age 34.3?±?16.1 years, 14 with multiple endocrine neoplasia type 2 (MEN2)] with clinical/biochemical suspicion of pheochromocytoma and suspicious adrenal lesion on contrast CT (n?=?70), who had undergone ⁶⁸Ga-DOTANOC PET/CT, were retrospectively analyzed. PET/CT images were analyzed visually as well as semiquantitatively, with measurement of maximum standardized uptake value (SUV_max), SUV_mean, SUV_max/SUV_liver, and SUV_mean/SUV_liver. Results of PET/CT were compared with ¹³¹I-metaiodobenzylguanidine (MIBG) imaging, which was available in 40 patients (45 lesions). Histopathology and/or imaging/clinical/biochemical follow-up (minimum 6 months) was used as reference standard.

Results

The sensitivity, specificity, and accuracy of ⁶⁸Ga-DOTANOC PET/CT was 90.4, 85, and 88.7 %, respectively, on patient-based analysis and 92, 85, and 90 %, respectively, on lesion-based analysis. ⁶⁸Ga-DOTANOC PET/CT showed 100 % accuracy in patients with MEN2 syndrome and malignant pheochromocytoma. On direct comparison, lesion-based accuracy of ⁶⁸Ga-DOTANOC PET/CT for pheochromocytoma was significantly higher than ¹³¹I-MIBG imaging (91.1 vs 66.6 %, p?=?0.035). SUV_max was higher for pheochromocytomas than other adrenal lesions (p?=?0.005), MEN2-associated vs sporadic pheochromocytoma (p?=?0.012), but no difference was seen between benign vs malignant pheochromocytoma (p?=?0.269).

Conclusion

⁶⁸Ga-DOTANOC PET/CT shows high diagnostic accuracy in patients with suspicion of pheochromocytoma and is superior to ¹³¹I-MIBG imaging for this purpose. Best results of ⁶⁸Ga-DOTANOC PET/CT are seen in patients with MEN2-associated and malignant pheochromocytoma.     

Glucose corrected standardized uptake value (SUVgluc) in the evaluation of brain lesions with 18F-FDG PET

Purpose

To retrospectively assess the utility of ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography (PET) images of standardized uptake values corrected for blood glucose (SUV_gluc), and to compare this to various quantitative methods to identify the presence or absence of high grade malignancy.

Methods

A retrospective review in 42 patients, found 81 central nervous system (CNS) lesions. Fifty one were malignant and 30 were benign or post treatment changes based on pathology (n?=?32) and on clinical outcome (n?=?49). Dynamic FDG PET scans were processed to generate parametric images of SUV_gluc, SUV, glucose metabolic rate (GMR), and lesion to cerebellum ratios (SUV_Rc), and contralateral white matter ratios (SUV_Rw). The SUV_gluc was calculated from $ {{{\mathrm{SU}{{\mathrm{V}}_{\max }}*\mathrm{BG}}} \left/ {{\left[ {100\,\mathrm{mg}/\mathrm{dl}} \right]}} \right.} $ , where SUV_max is the maximum SUV and BG is the blood glucose level (mg/dL).

Results

Using a malignant threshold for SUV_gluc of 4.5 and GMR of 13.0 μmole/min/100 g, the accuracies were similar for the SUV_gluc (80 %) and GMR (81 %) and were higher than the conventional SUV_max (73 %). The area under the receiver operating characteristic (ROC) curve for the SUV_gluc (0.8661) was better than that for the SUV_max (0.7955) (p?<?0.02) and was similar to those of the GMR (0.8694), SUV_Rc (0.8278), and SUV_Rw (0.8559).

Conclusion

These results suggest that the SUV_gluc may assist in the interpretation of FDG PET brain images in patients with CNS lesions. The SUV_gluc method avoids the complexity of kinetic modeling and the definition of a reference region.