Assessment of histological response of paediatric bone sarcomas using FDG PET in comparison to morphological volume measurement and standardized MRI parameters

Purpose

The objective of this study was to evaluate positron emission tomography (PET) using ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) in comparison to volumetry and standardized magnetic resonance imaging (MRI) parameters for the assessment of histological response in paediatric bone sarcoma patients.

Methods

FDG PET and local MRI were performed in 27 paediatric sarcoma patients [Ewing sarcoma family of tumours (EWS), n?=?16; osteosarcoma (OS), n?=?11] prior to and after neoadjuvant chemotherapy before local tumour resection. Several parameters for assessment of response of the primary tumour to therapy by FDG PET and MRI were evaluated and compared with histopathological regression of the resected tumour as defined by Salzer-Kuntschik.

Results

FDG PET significantly discriminated responders from non-responders using the standardized uptake value (SUV) reduction and the absolute post-therapeutic SUV (SUV2) in the entire patient population (?SUV, p?=?0.005; SUV2, p?=?0.011) as well as in the subgroup of OS patients (?SUV, p?=?0.009; SUV2, p?=?0.028), but not in the EWS subgroup. The volume reduction measured by MRI/CT did not significantly discriminate responders from non-responders either in the entire population (p?=?0.170) or in both subgroups (EWS, p?=?0.950; OS, p?=?1.000). The other MRI parameters alone or in combination were unreliable and did not improve the results. Comparing diagnostic parameters of FDG PET and local MRI, metabolic imaging showed high superiority in the subgroup of OS patients, while similar results were observed in the population of EWS.

Conclusion

FDG PET appears to be a useful tool for non-invasive response assessment in the group of OS patients and is superior to MRI. In EWS patients, however, neither FDG PET nor volumetry or standardized MRI criteria enabled a reliable response assessment to be made after neoadjuvant treatment.     

PET/MRI in head and neck cancer: initial experience

Purpose

To evaluate the feasibility of PET/MRI (positron emission tomography/magnetic resonance imaging) with FDG (¹⁸F-fluorodeoxyglucose) for initial staging of head and neck cancer.

Methods

The study group comprised 20 patients (16 men, 4 women) aged between 52 and 81?years (median 64?years) with histologically proven squamous cell carcinoma of the head and neck region. The patients underwent a PET scan on a conventional scanner and a subsequent PET/MRI examination on a whole-body hybrid system. FDG was administered intravenously prior to the conventional PET scan (267?C395?MBq FDG, 348?MBq on average). The maximum standardized uptake values (SUV_max) of the tumour and of both cerebellar hemispheres were determined for both PET datasets. The numbers of lymph nodes with increased FDG uptake were compared between the two PET datasets.

Results

No MRI-induced artefacts where observed in the PET images. The tumour was detected by PET/MRI in 17 of the 20 patients, by PET in 16 and by MRI in 14. The PET/MRI examination yielded significantly higher SUV_max than the conventional PET scanner for both the tumour (p?<?0.0001) and the cerebellum (p?=?0.0009). The number of lymph nodes with increased FDG uptake detected using the PET dataset from the PET/MRI system was significantly higher the number detected by the stand-alone PET system (64 vs. 39, p?=?0.001).

Conclusion

The current study demonstrated that PET/MRI of the whole head and neck region is feasible with a whole-body PET/MRI system without impairment of PET or MR image quality.     

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.     

Diagnostic value of combined 18F-FDG PET/MRI for staging and restaging in paediatric oncology

Purpose

The present study compares the diagnostic value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and MRI to combined/registered ¹⁸F-FDG PET/MRI for staging and restaging in paediatric oncology.

Methods

Over 8?years and 2?months, 270 ¹⁸F-FDG PET and 270 MRI examinations (mean interval 5?days) were performed in 132 patients with proven (n?=?117) or suspected (n?=?15) malignant disease: solid tumours (n?=?64), systemic malignancy (n?=?53) and benign disease (n?=?15). A total of 259 suspected tumour lesions were analysed retrospectively during primary diagnosis and 554 lesions during follow-up. Image analysis was performed separately on each modality, followed by analysis of combined and registered ¹⁸F-FDG PET/MRI imaging.

Results

A total of 813 lesions were evaluated and confirmed by histopathology (n?=?158) and/or imaging follow-up (n?=?655) after 6?months. In the separate analysis of ¹⁸F-FDG PET and MRI, sensitivity was 86?%/94?% and specificity 85?%/38?%. Combined/registered ¹⁸F-FDG PET/MRI led to a sensitivity of 97?%/97?% and specificity of 81?%/82?%. False-positive results (¹⁸F-FDG PET n?=?69, MRI n?=?281, combined ¹⁸F-FDG PET/MRI n?=?85, registered ¹⁸F-FDG PET/MRI n?=?80) were due to physiological uptake or post-therapeutic changes. False-negative results (¹⁸F-FDG PET n?=?50, MRI n?=?20, combined ¹⁸F-FDG PET/MRI n?=?11, registered ¹⁸F-FDG PET/MRI n?=?11) were based on low uptake or minimal morphological changes. Examination-based evaluation during follow-up showed a sensitivity/specificity of 91?%/81?% for ¹⁸F-FDG PET, 93?%/30?% for MRI and 96?%/72?% for combined ¹⁸F-FDG PET/MRI.

Conclusion

For the detection of single tumour lesions, registered ¹⁸F-FDG PET/MRI proved to be the methodology of choice for adequate tumour staging. In the examination-based evaluation, MRI alone performed better than ¹⁸F-FDG PET and combined/registered imaging during primary diagnosis. At follow-up, however, the examination-based evaluation demonstrated a superiority of ¹⁸F-FDG PET alone.     

18F-FDG PET/CT imaging versus dynamic contrast-enhanced CT for staging and prognosis of inflammatory breast cancer

Purpose

Inflammatory breast cancer (IBC) is the most aggressive type of breast cancer with a poor prognosis. Locoregional staging is based on dynamic contrast-enhanced (DCE) CT or MRI. The aim of this study was to compare the performances of FDG PET/CT and DCE CT in locoregional staging of IBC and to assess their respective prognostic values.

Methods

The study group comprised 50 women (median age: 51?±?11 years) followed in our institution for IBC who underwent FDG PET/CT and DCE CT scans (median interval 5?±?9 days). CT enhancement parameters were net maximal enhancement, net early enhancement and perfusion.

Results

The PET/CT scans showed intense FDG uptake in all primary tumours. Concordance rate between PET/CT and DCE CT for breast tumour localization was 92 %. No significant correlation was found between SUVmax and CT enhancement parameters in primary tumours (p?>?0.6). PET/CT and DCE CT results were poorly correlated for skin infiltration (kappa?=?0.19). Ipsilateral foci of increased axillary FDG uptake were found in 47 patients (median SUV: 7.9?±?5.4), whereas enlarged axillary lymph nodes were observed on DCE CT in 43 patients. Results for axillary node involvement were fairly well correlated (kappa?=?0.55). Nineteen patients (38 %) were found to be metastatic on PET/CT scan with a significant shorter progression-free survival than patients without distant lesions (p?=?0.01). In the primary tumour, no statistically significant difference was observed between high and moderate tumour FDG uptake on survival, using an SUVmax cut-off of 5 (p?=?0.7 and 0.9), or between high and low tumour enhancement on DCE CT (p?>?0.8).

Conclusion

FDG PET/CT imaging provided additional information concerning locoregional involvement to that provided by DCE CT on and allowed detection of distant metastases in the same whole-body procedure. Tumour FDG uptake or CT enhancement parameters were not correlated and were not found to have any prognostic value.     

<Superscript>11</Superscript>C-methylaminoisobutyric acid (MeAIB) PET for evaluation of prostate cancer: compared with <Superscript>18</Superscript>F-fluorodeoxyglucose PET

Objective

α-N-methyl-¹¹C-methylaminoisobutyric acid (¹¹C-MeAIB) is a selective substrate of system A amino acid transport, and known to accumulate in malignant lesions. The aim of this study was to evaluate the utility of MeAIB PET for the assessment of prostate cancer, compared with FDG PET.

Methods

Thirty-four men (age range 57–77 years) with prostate cancer were prospectively enrolled, and underwent MeAIB PET and FDG PET between January 2011 and January 2013. MeAIB PET and FDG PET were performed at 20 and 50 min post-injection, respectively. SUVmax of the prostate was calculated, and visual analysis was conducted for MeAIB and FDG PET studies. MRI images were visually evaluated if available. All patients received total prostatectomy subsequently, and imaging findings were compared with pathological results, including T stage, Gleason score, and tumor size. The patient-based and lesion-based sensitivity and specificity were calculated according to pathological significant cancer.

Results

Mean value of SUVmax of ¹¹C-MeAIB PET and ¹⁸F-FDG PET in prostate cancer were 3.18 (±1.90, range; 1.55–9.57) and 3.88 (±2.85, range; 2.04–14.47). MeAIB PET and FDG PET were positive by visual analysis in 47.1 % (16/34) and 44.1 % (15/34) of the patients. MRI was positive in 51.5 % (17/33). Pathological stage and Gleason score were as follows: Stage 2 (n = 23), 3 (n = 8), and 4 (n = 3); Gleason score 6 (n = 13), 7 (n = 16), 8 (n = 3), and 9 (n = 2). The sensitivities tended to be higher according to higher pathological T stage or Gleason sum score for both MeAIB and FDG PET studies. Visual analysis of both MeAIB PET and FDG PET had significant correlation with extraprostatic extension (p < 0.05). MeAIB PET and FDG PET had complementary results by visual analysis in the assessment of prostate cancer. The patient-based sensitivity of MeAIB PET, FDG PET, and MRI were 51.6, 48.4, and 56.7 %, respectively. The patient-based specificity of these modalities was 100 % for each modality.

Conclusions

MeAIB PET has better diagnostic results than FDG PET for the assessment of significant prostate cancer, and these PET studies showed complementary results. MRI has even better diagnostic results than ¹¹C-MeAIB PET. MeAIB accumulates in prostate cancer, which indicates that the system A amino acid transport pathway is activated in prostate cancer.

     

FDG PET as a prognostic predictor in the early post-therapeutic evaluation for unresectable hepatocellular carcinoma

Purpose

To elucidate the prognostic role of post-therapeutic ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET), we conducted a retrospective cohort study analysing the clinical factors that affect overall survival after non-operative therapy for unresectable hepatocellular carcinoma (HCC).

Methods

Sixty-seven cases with unresectable HCC who received non-operative therapy (transcatheter arterial chemoembolization: n?=?24, transcatheter arterial infusion chemotherapy: n?=?31, radiofrequency ablation: n?=?5 or systemic chemotherapy: n?=?7) and had received FDG PET for the evaluation of the therapeutic effect within 1 month after the end of the therapy were evaluated. Overall survival rate was evaluated using the univariate and multivariate analyses of relevant clinical and laboratory parameters before and after therapy, including visual PET analysis and quantitative analysis using maximum standardized uptake value (SUV).

Results

Visual PET diagnosis of post-therapeutic lesions was a good predictor of overall survival of unresectable HCC patients. The low FDG group showed significantly longer survival (average: 608 days) than that (average: 328 days) of the high FDG group (p?<?0.0001). Multivariate analysis showed four significant prognostic factors for the survival: post-therapeutic alpha-fetoprotein (αFP) level (=400 ng/ml, p?=?0.004), post-therapeutic visual PET diagnosis (p?=?0.006), post-therapeutic clinical stage (UICC stage IV, p?=?0.04) and post-therapeutic Milan criteria (p?=?0.03), while pre-therapeutic clinical factors, SUV by post-therapeutic FDG PET (5.0 or more) or others did not show significance.

Conclusion

The present study suggests that post-therapeutic PET performed within 1 month after non-operative therapy can be a good predictor of overall survival in unresectable HCC patients, while pre-therapeutic evaluation including PET, tumour markers and clinical staging may not be useful.     

Comparison of abdominal MRI with diffusion-weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas

Purpose

The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and ⁶⁸Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas.

Methods

Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w?+?DW MRI, T2w?+?contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar’s test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student’s t test.

Results

Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23?=?61 %; observer 2: 15/23?=?65.2 %; p?<?0.05) or CE T1w images (observer 1: 14/23?=?61 %; observer 2: 15/23?=?65.2 %; p?<?0.05). Detection rates of pancreatic NET with PET/CT (both observers: 23/23?=?100 %) were statistically significantly higher than with MRI (p?<?0.05). The mean ADC value of NET (1.02?±?0.26?×?10^?3?mm²/s) was statistically significantly lower than that of normal pancreatic tissue (1.48?±?0.39?×?10^?3?mm²/s).

Conclusion

DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. ⁶⁸Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET.     

Diagnostic Value of <Superscript>18</Superscript>F-FDG PET/CT and MRI in the Preoperative Evaluation of Uterine Carcinosarcoma

Purpose

This study aimed to compare the diagnostic value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and magnetic resonance imaging (MRI) in the preoperative evaluation of uterine carcinosarcoma.

Methods

Fifty-four women with pathologically confirmed uterine carcinosarcoma who underwent preoperative FDG PET/CT and MRI from June 2006 to November 2016 were included. Pathologic findings from primary tumor lesions, para-aortic and pelvic lymph node (LN) areas, and peritoneal seeding lesions were compared with the FDG PET/CT and MRI findings. The maximum standardized uptake value (SUVmax) of the primary tumor and LN was obtained. The tumor-to-liver ratio (TLR) was calculated by dividing the SUVmax of the primary tumor or LN by the mean SUV of the liver.

Results

For detecting primary tumor lesions (n?=?54), the sensitivity and accuracy of FDG PET/CT (53/54) and MRI (53/54) were 98.2%. The sensitivity, specificity, and accuracy of FDG PET/CT versus MRI were as follows: 63.2% (12/19) versus 26.3% (5/19), 100% (35/35) versus 100% (35/35), and 87.0% versus 74.0%, respectively, for pelvic LN areas (p?=?0.016); 85.7% (12/14) versus 42.9% (6/14), 90% (36/40) versus 97.5% (39/40), and 88.9% versus 83.3%, respectively, for para-aortic LN areas (p?=?0.004); and 59.4% (19/32) versus 50% (16/32), 100% (22/22) versus 100% (22/22), and 75.9% versus 70.4%, respectively, for peritoneal seeding lesions (p?=?0.250). For distant metastasis, the sensitivity, specificity, and accuracy of FDG PET/CT were 100 (8/8), 97.8 (45/46), and 98.2%, respectively.

Conclusions

FDG PET/CT showed superior diagnostic accuracy compared to MRI in detecting pelvic and para-aortic LN metastasis in patients with uterine carcinosarcoma. Moreover, FDG PET/CT facilitated the identification of distant metastasis.

     

Malignancy rate of biopsied suspicious bone lesions identified on FDG PET/CT

Purpose

To determine the malignancy rate of bone lesions identified on FDG PET/CT in patients who have undergone CT-guided biopsy because of the suspicion of malignancy.

Methods

This single-centre retrospective study spanned eight consecutive years and included all patients who underwent both FDG PET/CT and CT-guided bone biopsy because of the suspicion of malignancy. The positive predictive value (PPV) for malignancy was calculated, and different patient and imaging characteristics were compared between malignant and benign bone lesions.

Results

Of 102 included patients with bone lesions that all showed FDG uptake exceeding mediastinal uptake, bone biopsy showed a malignant lesion in 91 patients, yielding a PPV for malignancy of 89.2 % (95 % CI 81.7 – 93.9 %). In the 94 patients with bone lesions that showed FDG uptake exceeding liver uptake, bone biopsy showed a malignant lesion in 83 patients, yielding a PPV for malignancy of 88.3 % (95 % CI 80.1 – 93.5 %). Higher age, bone marrow replacement of the lesion seen on CT, expansion of the lesion seen on CT, and presence of multifocal lesions on FDG PET/CT were significantly more frequent in patients with malignant lesions than in those with benign bone lesions (P?=?0.044, P?=?0.009, P?=?0.015, and P?=?0.019, respectively). Furthermore, there was a trend towards a higher incidence of cortical destruction (P?=?0.056) and surrounding soft tissue mass (P?=?0.063) in patients with malignant bone lesions.

Conclusion

The PPV for malignancy of suspicious bone lesions identified on FDG PET/CT is not sufficiently high to justify changes in patient management without histopathological confirmation. Nevertheless, ancillary patient and imaging characteristics may increase the likelihood of a malignant bone lesion.

     

Diagnostic value of diffusion-weighted magnetic resonance imaging (DWI) compared to FDG PET/CT for whole-body breast cancer staging

Purpose

The aim of the study was to prospectively compare the diagnostic value of whole-body diffusion-weighted imaging (DWI) and FDG PET/CT for breast cancer (BC) staging.

Methods

Twenty BC patients underwent whole-body FDG PET/CT and 1.5-T DWI. Lesions with qualitatively elevated signal intensity on DW images (b?=?800 s/mm²) were rated as suspicious for tumour and mapped to individual lesions and different compartments (overall 552 lesions). The apparent diffusion coefficient (ADC) value was determined for quantitative evaluation. Histopathology, MRI findings, bone scan findings, concordant findings between FDG PET/CT and DWI, CT follow-up scans and plausibility served as the standards of reference defining malignancy.

Results

According to the standards of reference, breasts harboured malignancy in 11, regional lymph nodes in 4, M1 lymph nodes in 3, bone in 7, lung in 2, liver in 3 and other tissues in 3 patients. On a compartment basis, the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) for the detection of malignancies were 94, 99, 98, 97 and 98% for FDG PET/CT and 91, 72, 76, 50 and 96% for DWI, respectively. Of the lesions seen on DWI only, 348 (82%) turned out to be false-positive compared to 23 (11%) on FDG PET/CT. The average lesion ADC was 820?±?300 with true-positive lesions having 929?±?252 vs 713?±?305 in false-positive lesions (p?<?0.0001).

Conclusion

Based on these initial data DWI seems to be a sensitive but unspecific modality for the detection of locoregional or metastatic BC disease. There was no possibility to quantitatively distinguish lesions using ADC. DWI alone may not be recommended as a whole-body staging alternative to FDG PET(/CT). Further studies are necessary addressing the question of whether full-body MRI including DWI may become an alternative to FDG PET/CT for whole-body breast cancer staging.     

Prostatic ductal adenocarcinoma: an aggressive tumour variant unrecognized on T2 weighted magnetic resonance imaging (MRI)

Introduction

Prostatic ductal adenocarcinoma (DCa) is an aggressive variant. The purpose of this study was to determine if T2 signal intensity (SI) differs from conventional adenocarcinoma (CCa).

Materials and methods

A retrospective study of patients who underwent preoperative MRI and prostatectomy between 2009 and 2012 was performed. T2 SI ratios (SIR) for tumour (T) to obturator internus muscle (M) and normal peripheral zone (PZ) were compared. Two radiologists evaluated the central gland/PZ to detect tumours and compared diagnostic accuracy.

Results

T2 SIR for DCa were 3.60 (T/M), 0.66 (T/PZ); 2.68 (T/M), 0.47 (T/PZ) for Gleason 9; 2.50 (T/M), 0.47 (T/PZ) for Gleason 7/8 and 3.95 (T/M), 0.73 (T/PZ) for Gleason 6 tumours. There was a difference in T2 T/M and T/PZ SIR between DCa and Gleason 9 (p?=?0.003, p?=?0.004) and Gleason 7/8 (p?=?0.006, p?=?0.002), but no difference in SIR between DCa and Gleason 6 tumours. The sensitivity for tumour detection was 0–27 % for DCa, 64–82 % for Gleason 9, 44–88 % for Gleason 7–8 and 0–20 % for Gleason 6. There was a difference in the sensitivity of detecting Gleason 9 and 7/8 tumours when compared to DCa (p?=?0.004, p?=?0.001).

Conclusions

DCa resembles Gleason score 6 tumour at T2-weighted MRI, which underestimates tumour grade and renders the tumour occult.

Key Points

? Prostatic ductal adenocarcinoma is aggressive, resembling endometrial carcinoma at histopathology. ? Prostatic ductal adenocarcinoma resembles Gleason score 6 tumour at T2-weighted MRI. ? MRI grading may underestimate ductal adenocarcinoma based on increased T2 signal.     

Preoperative PET/CT FDG standardized uptake value of pelvic lymph nodes as a significant prognostic factor in patients with uterine cervical cancer

Purpose

Using integrated PET/CT, we evaluated the prognostic relevance in uterine cervical cancer of preoperative pelvic lymph node (LN) [¹⁸F]FDG uptake.

Methods

Patients with FIGO stage IB to IIA uterine cervical cancer were imaged with FDG PET/CT before radical surgery. We used Cox proportional hazards regression to examine the relationship between recurrence and the FDG maximum standardized uptake value (SUV_max) in the pelvic LN (SUV_LN) on PET/CT.

Results

Clinical data, treatment modalities, and results in 130 eligible patients were reviewed. The median postsurgical follow-up was 34 months (range 6 to 109 months). Receiver operating characteristic analysis identified SUV_LN 2.36 as the most significant cut-off value for predicting recurrence. SUV_LN was correlated with SUV_tumour (P?=?0.002), primary tumour size (P?=?0.004), and parametrial invasion (P?=?0.013). Univariate analyses showed significant associations between recurrence and SUV_LN (P?=?0.001), SUV_tumour (P?=?0.007), pelvic LN metastasis (P?=?0.002), parametrial invasion (P?<?0.001), primary tumour size (P?=?0.007), suspected LN metastasis on MRI (P?=?0.024), and FIGO stage (P?=?0.026). Multivariate analysis identified SUV_LN (P?=?0.013, hazard ratio, HR, 4.447, 95 % confidence interval, CI, 1.379 – 14.343) and parametrial invasion (P?=?0.013, HR 6.728, 95 % CI 1.497 – 30.235) as independent risk factors for recurrence. Patients with SUV_LN ≥2.36 and SUV_LN <2.36 differed significantly in terms of recurrence (HR 15.20, P?<?0.001).

Conclusion

Preoperative pelvic LN FDG uptake showed a strong significant association with uterine cervical cancer recurrence.     

An exploratory pilot study into the association between microcirculatory parameters derived by MRI-based pharmacokinetic analysis and glucose utilization estimated by PET-CT imaging in head and neck cancer

Objectives:

To examine the feasibility of deriving quantitative microcirculatory parameters and to investigate the relationship between vascular and metabolic characteristics of head and neck tumours in vivo, using dynamic contrast-enhanced (DCE) MRI and fluorodeoxyglucose (FDG) PET imaging.

Methods:

Twenty-seven patients with primary squamous cell carcinoma (SCCA) underwent DCE-MRI and combined PET/CT imaging. DCE-MRI data were post-processed by using commercially available software. Transfer constant (K ^trans), extravascular extracellular blood volume (v _e), transfer constant from the extracellular extravascular space to plasma (k _ep) and iAUC (initial area under the signal intensity–time curve) were calculated. 3D static PET data were acquired and standardised uptake values (SUV) calculated.

Results:

All microcirculatory parameters in tumours were higher than in normal muscle tissue (P?≤?0.0019). Significant correlations were shown between k _ep and K ^trans (ρ?=?0.77), v _e and k _ep (ρ?=??0.7), and iAUC and v _e (ρ?=?0.53). Significant correlations were observed for SUV_mean and v _e as well as iAUC (ρ?=?0.42 and ρ?=?0.66, respectively). SUV_max was significantly correlated with iAUC (ρ?=?0.69).

Conclusions:

The demonstrated relationships between vascular and metabolic characteristics of primary SCCA imply a complex interaction between vascular delivery characteristics and tumour metabolism. The lack of correlation between SUV and K ^trans/k _ep suggests that both diagnostic techniques may provide complementary information.     

Impact of a second FDG PET scan before adjuvant therapy for the early detection of residual/relapsing tumours in high-risk patients with oral cavity cancer and pathological extracapsular spread

Purpose

Extracapsular spread (ECS) to the cervical lymph nodes is a major adverse prognostic factor in oral cavity squamous cell carcinoma (OSCC). We prospectively examined the value of FDG PET immediately before postoperative radiotherapy/concurrent chemoradiotherapy (pre-RT/CCRT PET) to detect residual/relapsing disease in the early postsurgical follow-up period in high-risk OSCC patients with ECS.

Methods

We examined 183 high-risk OSCC patients with ECS who underwent preoperative FDG PET/CT for staging purposes. Of these patients, 29 underwent a second pre-RT/CCRT FDG PET/CT scan. The clinical utility of the second FDG PET/CT was examined using Kaplan-Meier curve analysis.

Results

Patients who underwent the second FDG PET/CT scan had baseline clinicopathological characteristics similar to those who did not undergo a second scan. Of the patients who underwent the second scan, seven (24?%) had unexpected, newly discovered lesions. Five eventually died of the disease, and two had no evidence of recurrence after a change in RT field and dose. In an event-based analysis at 2?months, rates of neck control (6/29 vs. 6/154, p?=?0.001), distant metastases (3/29 vs. 4/154, p?=?0.046), and disease-free survival (7/29 vs. 10/154, p?=?0.003) were significantly higher in patients who received a second PET scan than in those who did not. The second pre-RT/CCRT PET scan was of particular benefit for detecting new lesions in OSCC patients with both ECS and lymph node standardized uptake value (SUV) of ≥5.2 in the first PET scan.

Conclusion

The present findings support the clinical value of pre-RT/CCRT FDG PET for defining treatment strategy in OSCC patients with both ECS and high nodal SUV, even when FDG PET had already been performed during the initial staging work-up.     

Clinical and survival impact of FDG PET in patients with suspicion of recurrent cervical carcinoma

Purpose

The aim of this retrospective study was to evaluate the contribution of ¹⁸F-FDG PET to the clinical management and survival outcome of patients suspected of recurrent cervical carcinoma and in line with the hypothesis that early diagnosis of recurrent cervical cancer may improve overall survival.

Methods

A total of 40 patients underwent conventional imaging (CI) and FDG PET/CT for suspected cervical cancer. Clinical management decisions were recorded with CI and additional PET/CT. Discordances and concordances between CI and PET/CT results were compared to the final diagnosis as based on histopathology analysis or follow-up considered as the gold standard.

Results

The final diagnosis was established pathologically (n?=?25) or by median clinical follow-up for 48 months after the PET (n?=?15). The PET/CT was positive in 76% (20/26) of patients compared to 19% (6/26) with CI. Globally PET/CT modified the treatment plan in 55% (22/40) of patients and in 75% (18/24) when the CI was negative prior to PET/CT. These changes led to the use of previously unplanned therapeutic procedures in 37.5% (15/40). When FDG PET was positive for recurrence (>?3 foci), the median overall survival was 12 months (2–70) compared to patients with PET findings with ≤?1 focus for which the median survival was not attained (p?=?0.007). A multivariate analysis of prognostic factors demonstrated that abnormal FDG uptake (>?3 foci) was the most significant factor (p?<?0.03) for death from cervical cancer.

Conclusion

FDG PET is a valuable tool in the case of suspected recurrence of cervical cancer on account of its impact on treatment planning and especially in predicting patient outcome.     

Direct comparison of [18F]FDG PET/CT with PET alone and with side-by-side PET and CT in patients with malignant melanoma

Purpose

The purpose of this retrospective, blinded study was to evaluate the additional value of [¹⁸F]FDG PET/CT in comparison with PET alone and with side-by-side PET and CT in patients with malignant melanoma (MM).

Methods

A total of 127 consecutive studies of patients with known MM referred for a whole-body PET/CT examination were included in this study. PET alone, side-by-side PET and CT and integrated PET/CT study were independently and separately interpreted without awareness of the clinical information. One score each was applied for certainty of lesion localisation and for certainty of lesion characterisation. Verification of the findings was subsequently performed using all available clinical, pathological (n?=?30) and follow-up information.

Results

The number of lesions with an uncertain localisation was significantly (p?p?p?=?0.057) compared versus PET alone. Respectively, PET, side-by-side PET and CT and PET/CT showed a sensitivity of 86%, 89% and 91%, a specificity of 94%, 94% and 94%, a positive predictive value of 96%, 96% and 96% and a negative predictive value of 80%, 83% and 87%.

Conclusion

Integrated PET/CT offers a significant benefit in lesion localisation and an improvement in lesion characterisation compared with PET alone or with side-by-side PET and CT. The benefit is not as great as that reported for other tumour entities, which may be due to the high avidity of MM for [¹⁸F]FDG.     

Whole-body [18F]FDG PET/MRI vs. PET/CT in the assessment of bone lesions in oncological patients: initial results

Objectives

To compare [¹⁸?F]FDG PET/MRI with PET/CT for the assessment of bone lesions in oncologic patients.

Methods

This prospective study included 67 patients with solid tumours scheduled for PET/CT with [¹⁸?F]FDG who also underwent a whole-body PET/MRI scan. The datasets (PET/CT, PET/MRI) were rated by two readers regarding lesion conspicuity (four-point scale) and diagnostic confidence (five-point scale). Median scores were compared using the Wilcoxon test.

Results

Bone metastases were present in ten patients (15 %), and benign bone lesions in 15 patients (22 %). Bone metastases were predominantly localized in the pelvis (18 lesions, 38 %) and the spine (14 lesions, 29 %). Benign bone lesions were exclusively osteosclerotic and smaller than the metastases (mean size 6 mm vs. 23 mm). While PET/CT allowed identification of 45 of 48 bone metastases (94 %), PET/MRI allowed identification of all bone metastases (100 %). Conspicuity of metastases was high for both modalities with significantly better results using PET/MRI (p?<?0.05). Diagnostic confidence in lesion detection was high for both modalities without a significant difference. In benign lesions, conspicuity and diagnostic confidence were significantly higher with PET/CT (p?<?0.05).

Conclusions

[¹⁸?F]FDG PET/MRI shows high potential for the assessment of bone metastases by offering superior lesion conspicuity when compared to PET/CT. In hypersclerotic, benign bone lesions PET/CT still sets the reference.

Key Points

? PET/MRI and PET/CT are of equal value for the identification of disease-positive patients ? PET/MRI offers higher lesion conspicuity as well as diagnostic confidence ? PET/MRI is an attractive new alternative for the assessment of bone metastases     

Indeterminate pleural metastasis on contrast-enhanced chest CT in non-small cell lung cancer: improved differential diagnosis with 18F-FDG PET/CT

Purpose

To evaluate the diagnostic performance of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT (PET/CT) for determining the presence of pleural metastasis in patients with indeterminate findings on a contrast-enhanced chest CT (CECT) for non-small cell lung cancer (NSCLC).

Materials and methods

This is a retrospective study. NSCLC patients (n?=?63) who underwent thoracentesis and/or pleural biopsy were enrolled. CECT and PET/CT reports of pleural metastasis were analyzed based on comparison with cytological or histological confirmation. Negative cytologic results were re-confirmed with follow-up study prior to cancer-related therapy. CECT results were classified into 3 categories: negative, indeterminate, and positive for pleural metastasis. PET/CT results were classified into 2 categories (negative and positive for pleural metastasis) based on FDG uptake visual grading. The level of max SUV of pleura was also analyzed. ROC analysis was done for establishing the max SUV cut-off value.

Result

PET/CT could differentiate pleural metastasis with 70.8% diagnostic accuracy when the CECT finding was indeterminate (n?=?24). Optimal cut-off value to predict pleural metastasis was 2.8 for max SUV. Diagnosis by max SUV 2.8 had lower sensitivity (86.3 vs. 92.2%), but higher specificity (66.7 vs. 58.3%) than PET/CT by FDG visual grading criteria.

Conclusion

PET/CT showed better diagnostic performance than CECT for detecting pleural metastasis in NSCLC patients. When the finding of CECT is controversial, PET/CT can differentiate the metastatic pleural lesion. Both FDG uptake visual grading and max SUG cut-off value can be used as diagnostic criteria for pleural metastasis.     

PET/CT for staging and follow-up of pediatric nasopharyngeal carcinoma

Purpose

While FDG PET/CT for the evaluation of nasopharyngeal carcinoma (NPC) in adult patients has documented advantages and disadvantages compared with conventional imaging, to our knowledge, no studies of FDG PET/CT for the evaluation of NPC in pediatric patients have been performed. In this investigation, we studied the utility of FDG PET/CT in children with NPC.

Methods

The study group comprised 18 children with biopsy-proven NPC who underwent FDG PET/CT and MRI (total 38 pairs of images). All baseline and follow-up FDG PET/CT and MRI studies were independently reviewed for restaging of disease.

Results

The concordance between FDG PET/CT and MRI in T, N, and overall staging was 29%, 64%, and 43%, respectively. Compared with MRI, FDG PET/CT yielded lower T and overall staging and showed less cervical and retropharyngeal lymphadenopathy. The concordance between follow-up FDG PET/CT and MRI was 79% overall and 100% 9?months after therapy. In patients who achieved complete remission, FDG PET/CT showed disease clearance 3–6?months earlier than MRI. There were no false-positive or false-negative FDG PET/CT scans during follow-up.

Conclusion

FDG PET/CT may underestimate tumor extent and regional lymphadenopathy compared with MRI at the time of diagnosis, but it helps to detect metastases and clarify ambiguous findings. FDG PET/CT is sensitive and specific for follow-up and enables earlier determination of disease remission. FDG PET/CT is a valuable imaging modality for the evaluation and monitoring of NPC in pediatric patients.