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.     

The Role of F-18 FDG PET/CT in Intrahepatic Cholangiocarcinoma

Purpose

The aim of this study was to evaluate the diagnostic and prognostic role of metabolic parameters of FDG PET/CT in patients with intrahepatic cholangiocarcinoma (ICC).

Methods

From December 2008 to December 2013, 76 FDG PET/CT scans performed for initial staging of ICC in a single institution (57 male and 19 female; mean age 68?±?9 years) were retrospectively reviewed. Patients with history of other known malignancy were excluded. Detection rates of regional lymph node and distant metastasis by FDG PET/CT were analyzed in comparison with conventional imaging modalities such as CT or MRI. Metabolic parameters including maximum, peak and mean standardized uptake values (SUVmax, SUVpeak, SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG), glucose corrected SUV (SUVgluc), and glucose corrected TLG (TLGgluc) were measured for the primary tumor. Cut-off values for the metabolic parameters were calculated by ROC curve analysis, and used to dichotomize the patient groups. The overall survival time (OS) was calculated and compared using the Cox proportional hazard regression analysis.

Results

The median duration of follow-up period was 5.4 months (interquartile range: 1.45～15.45). FDG PET/CT showed higher sensitivity than conventional imaging modalities in detection of regional node involvement (74.5 % vs. 61.8 %, p?=?0.013). In six patients, distant metastasis was identified only by FDG PET/CT. The mean SUVmax, SUVpeak, SUVmean, MTV, and TLG for the primary tumor were 8.2?±?3.1, 6.8?±?2.5, 4.0?±?0.8, 192.7?±?360.5 cm³, and 823.7?±?1615.4, respectively. Patients with higher (≥7.3, HR: 4.280, p?=?0.001), higher SUVpeak (≥6.5, HR: 2.333, p?=?0.020), higher SUVmean (≥3.9, HR: 2.799, p?=?0.004), higher SUVgluc (≥8.1, HR: 2.648, p?=?0.012), and higher TLGgluc (≥431.6, HR: 2.186, p?=?0.030) showed significantly shorter survival time. By multivariate study, operability was an independent prognostic factor for longer survival (HR: 4.113, p?=?0.005).

Conclusion

FDG PET/CT is an important diagnostic imaging tool in the nodal staging and detection of distant metastasis in ICC patients. Metabolic parameters may have a significant role as prognostic factors in patients with ICC.

     

Correlation of breast cancer subtypes,based on estrogen receptor,progesterone receptor,and HER2, with functional imaging parameters from 68Ga-RGD PET/CT and 18F-FDG PET/CT

Purpose

Imaging biomarkers from functional imaging modalities were assessed as potential surrogate markers of disease status. Specifically, in this prospective study, we investigated the relationships between functional imaging parameters and histological prognostic factors and breast cancer subtypes.

Methods

In total, 43 patients with large or locally advanced invasive ductal carcinoma (IDC) were analyzed (47.6?±?7.5 years old). ⁶⁸Ga-Labeled arginine-glycine-aspartic acid (RGD) and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) were performed. The maximum and average standardized uptake values (SUV_max and SUV_avg) from RGD PET/CT and SUV_max and SUV_avg from FDG PET/CT were the imaging parameters used. For histological prognostic factors, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression was identified using immunohistochemistry (IHC) or fluorescent in situ hybridization (FISH). Four breast cancer subtypes, based on ER/PR and HER2 expression (ER/PR+,Her2?, ER/PR+,Her2+, ER/PR?,Her2+, and ER/PR?,Her2?), were considered.

Results

Quantitative FDG PET parameters were significantly higher in the ER-negative group (15.88?±?8.73 vs 10.48?±?6.01, p?=?0.02 for SUV_max; 9.40?±?5.19 vs 5.92?±?4.09, p?=?0.02 for SUV_avg) and the PR-negative group (8.37?±?4.94 vs 4.79?±?3.93, p?=?0.03 for SUV_avg). Quantitative RGD PET parameters were significantly higher in the HER2-positive group (2.42?±?0.59 vs 2.90?±?0.75, p?=?0.04 for SUV_max; 1.60?±?0.38 vs 1.95?±?0.53, p?=?0.04 for SUV_avg) and showed a significant positive correlation with the HER2/CEP17 ratio (r?=?0.38, p?=?0.03 for SUV_max and r?=?0.46, p?<?0.01 for SUV_avg). FDG PET parameters showed significantly higher values in the ER/PR?,Her2? subgroup versus the ER/PR+,Her2? or ER/PR+,Her2+ subgroups, while RGD PET parameters showed significantly lower values in the ER/PR?,Her2? subgroup versus the other subgroups. There was no correlation between FDG and RGD PET parameters in the overall group. Only the ER/PR?,Her2? subgroup showed a significant positive correlation between FDG and RGD PET parameters (r?=?0.59, p?=?0.03 for SUV_max).

Conclusion

⁶⁸Ga-RGD and ¹⁸F-FDG PET/CT are promising functional imaging modalities for predicting biomarkers and molecular phenotypes in breast cancer patients.     

Prognostic value of volumetric parameters measured by 18F-FDG PET/CT in patients with head and neck squamous cell carcinoma

Purpose

The objective of this study was to investigate the value of metabolic tumour volume (MTV) assessed with ¹⁸F-FDG PET/CT in predicting event-free survival (EFS) and overall survival (OS) in patients with head and neck squamous cell carcinoma (HNSCC), and particularly to compare it with more conventional parameters such as maximum standardized uptake value (SUVmax).

Methods

Patients referred to our department for ¹⁸F-FDG PET/CT for staging of HNSCC were prospectively included between February 2009 and March 2011. Each patient was scanned using a Philips Gemini PET/CT system at 1 h after injection. The MTV was calculated semiautomatically for the primary site using methods based on SUV with various thresholds: 3-D contour around voxels equal to or greater than 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 times SUV, or more than 30 %, 40 % and 50 % of SUVmax. ROC analysis was used to test the statistical significance of the differences among the calculated MTVs. EFS and OS were determined using the Kaplan-Meier method and compared with MTV in univariate and multivariate analyses, including the usual prognostic factors: age, sex, primary site, treatment, SCC histologic grade, AJCC stage, TNM classification, tumour SUVmax and SUVpeak.

Results

The study included 80 consecutive patients (70 men, 10 women; mean age 62.4?±?9.0 years). ROC analysis revealed that pretreatment MTV using a threshold of 5.0 times SUV (MTV5.0) was the best parameter to predict recurrence and death after treatment. In univariate analysis, MTV5.0 >4.9 ml was predictive of poor EFS (p?<?0.0001) and poor OS (p?<?0.0001). In multivariate, MTV5.0 persisted as an independent predictive factor for EFS (p?=?0.011) and OS (p?=?0.010), while SUVmax became nonsignificant (p?=?0.277 for EFS, p?=?0.975 for OS).

Conclusion

Our results suggest that MTV measured by ¹⁸F-FDG PET/CT has independent prognostic value of in patients with HNSCC, stronger than SUVmax.     

Breast cancer detection using high-resolution breast PET compared to whole-body PET or PET/CT

Purpose

To compare the performance characteristics of positron emission mammography (PEM) with those of whole-body PET (WBPET) and PET/CT in women with newly diagnosed breast cancer.

Methods

A total of 178 women consented to PEM for presurgical planning in an IRB-approved protocol and also underwent either WBPET (n?=?69) or PET/CT (n?=?109) imaging, as per usual care at three centers. Tumor detection sensitivity, positive predictive values, and ¹⁸F-fluorodeoxyglucose (FDG) uptake were compared between the modalities. The effects of tumor size, type, and grade on detection were examined. The chi-squared or Fisher’s exact tests were used to compare distributions between groups, and McNemar’s test was used to compare distributions for paired data within subject groups, i.e. PEM versus WBPET or PEM versus PET/CT.

Results

The mean age of the women was 59?±?12 years (median 60 years, range 26–89 years), with a mean invasive index tumor size of 1.6?±?0.8 cm (median 1.5 cm, range 0.5–4.0 cm). PEM detected more index tumors (61/66, 92 %) than WBPET (37/66, 56 %; p?<?0.001) or PET/CT (95/109, 87 % vs. 104/109, 95 % for PEM; p?<?0.029). Sensitivity for the detection of additional ipsilateral malignancies was also greater with PEM (7/15, 47 %) than with WBPET (1/15, 6.7 %; p?=?0.014) or PET/CT (3/23, 13 % vs. 13/23, 57 % for PEM; p?=?0.003). Index tumor detection decreased with decreasing invasive tumor size for both WBPET (p?=?0.002) and PET/CT (p?<?0.001); PEM was not significantly affected (p?=?0.20). FDG uptake, quantified in terms of maximum PEM uptake value, was lowest in ductal carcinoma in situ (median 1.5, range 0.7–3.0) and invasive lobular carcinoma (median 1.5, range 0.7–3.4), and highest in grade III invasive ductal carcinoma (median 3.1, range 1.4–12.9).

Conclusion

PEM was more sensitive than either WBPET or PET/CT in showing index and additional ipsilateral breast tumors and remained highly sensitive for tumors smaller than 1 cm.     

Recurrent bladder carcinoma: clinical and prognostic role of 18 F-FDG PET/CT

Aim

A small number of studies evaluated the detection rate of lesions from bladder carcinoma (BC) of 18 F-FDG PET/CT in the restaging process. However, the prognostic role of FDG PET/CT still remains unclear. The aim of the present study was to evaluate the accuracy, the effect upon treatment decision, and the prognostic value of FDG PET/CT in patients with suspected recurrent BC.

Materials and Methods

Forty-one patients affected by BC underwent FDG PET/CT for restaging purpose. The diagnostic accuracy of visually interpreted FDG PET/CT was assessed compared to histology (n?=?8), other diagnostic imaging modalities (contrast-enhanced CT in 38/41 patients and MRI in 15/41) and clinical follow-up (n?=?41). Semiquantitative PET values (SUVmax, SUVmean, SUL, MTV, TLG) were calculated using a graph-based method. Progression-free survival (PFS) and overall survival (OS) were assessed by using Kaplan-Meier curves. The risk of progression (hazard ratio, HR) was computed by Cox regression analysis by considering all the available variables.

Results

PET was considered positive in 21 of 41 patients. Of these, recurrent BC was confirmed in 20 (95 %). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG PET/CT were 87 %, 94 %, 95 %, 85 %, 90 %. AUC was 0.9 (95 %IC 0.8-1). Bayesian positive and negative likelihood ratios were 14.5 and 0.13, respectively. FDG PET/CT findings modified the therapeutic approach in 16 patients (modified therapy in 10 PET-positive patients, watch-and-wait in six PET-negative patients). PFS was significantly longer in patients with negative scan vs. those with pathological findings (85 % vs. 24 %, p?<?0.05; HR?=?12.4; p?=?0.001). Moreover, an unremarkable study was associated with a longer OS (88 % vs. 47 % after 2 years and 87 % vs. 25 % after 3 years, respectively, p?<?0.05). Standardized uptake value (SUV)max?>?6 and total lesion glycolysis (TLG)?>?8.5 were recognized as the most accurate thresholds to predict PFS (2-year PFS 62 % for SUVmax?<?6 vs. 15 % for SUVmax?>?6, p?=?0.018; 2-year PFS 66 % for TLG?<?8.5 vs. 18 % for TLG?>?8.5, p?=?0.09).

Conclusion

A very good diagnostic performance for FDG PET/CT was confirmed in patients with suspected recurrent BC. FDG PET/CT allowed for a change in treatment decision in about 40 % of cases and showed an important prognostic value in assessing PFS and OS.

     

Comparison of the prognostic values of 68Ga-DOTANOC PET/CT and 18F-FDG PET/CT in patients with well-differentiated neuroendocrine tumor

Purpose

To determine the prognostic value of ⁶⁸Ga-DOTANOC PET/CT in patients with well-differentiated neuroendocrine tumor (NET), and to compare the prognostic value with that of ¹⁸F-FDG PET/CT and other conventional clinicopathological prognostic factors.

Methods

Data from 37 consecutive patients (age 46.6?±?13.5 years, 51 % men) with well-differentiated NET who underwent ⁶⁸Ga-DOTANOC PET/CT and ¹⁸F-FDG PET/CT were analyzed. All patients underwent a baseline visit with laboratory and radiological examinations. Clinical and imaging follow-up was performed in all patients. Progression-free survival (PFS) was measured from the date of the first PET/CT scan to the first documentation of progression of disease.

Results

⁶⁸Ga-DOTANOC PET/CT was positive in 37 of the 37 patients and ¹⁸F-FDG PET/CT was positive in 21. During follow-up 10 patients (27 %) showed progression of disease and 27 (73 %) showed no progression (24 stable disease, 3 partial response). The median follow-up was 25 months (range 2 – 52 months). Among the variables evaluated none was significantly different between the progressive disease and nonprogressive disease groups, with only SUVmax on ⁶⁸Ga-DOTANOC PET/CT being borderline significant (P?=?0.073). In the univariate analysis for PFS outcome, SUVmax on ⁶⁸Ga-DOTANOC PET/CT (HR 0.122, 95 % CI 0.019 – 0.779; P?=?0.026) and histopathological tumor grade (HR 4.238, 95 % CI 1.058 – 16.976; P?=?0.041) were found to be associated with PFS. Other factors including age, sex, primary site, Ki-67 index, TNM stage, ¹⁸F-FDG PET/CT status (positive/negative), SUVmax on ¹⁸F-FDG PET/CT and type of treatment were not significant. In multivariable analysis, only SUVmax on ⁶⁸Ga-DOTANOC PET/CT was found to be an independent positive predictor of PFS (HR 0.122, 95 % CI 0.019 – 0.779; P?=?0.026).

Conclusion

SUVmax measured on ⁶⁸Ga-DOTANOC PET/CT is an independent, positive prognostic factor in patients with well-differentiated NET and is superior to SUVmax on ¹⁸F-FDG PET/CT and conventional clinicopathological factors for predicting PFS.     

Somatostatin receptor scintigraphy with 111In-octreotide in pulmonary carcinoid tumours correlated with pathological and 18FDG PET/CT findings

Purpose

Pulmonary carcinoid (PC) tumors are rare neoplasms of the lung with good prognosis but diagnosis may be demanding since there is no exclusive modality alone to clearly differentiate a PC tumor. The purpose of this study is to establish the diagnostic features of somatostatin receptor scintigraphy (SRS), comparatively (where available) with ¹⁸FDG PET/CT (PET/CT) correlated with histopathologic findings.

Methods

Twenty-one patients who underwent SRS with ¹¹¹In-octreotide and were diagnosed as having PC tumors were retrospectively studied. Thirteen patients were performed PET/CT. Primary tumour size, Ki-67 indexes, image analysis data of SRS and PET/CT including maximum standardized uptake values (SUVmax) together with false negative, false positive, true positive and true negative lesions were documented and discussed.

Results

Eleven (52.4?%) patients were typical (TC) and 10 (47.6?%) were atypical carcinoids (AC) with mean Ki-67 indexes of 2.1 and 24?%, respectively. Patients underwent SRS for solitary pulmonary nodule (SPN) characterization (n?=?12) and determination of disease extension (n?=?9). Overall sensitivity and specificity of SRS in the detection of primary tumour, lymph nodes (LN) and distant metastasis (DM) were 76 and 97?%, respectively, whereas, positive and negative predictive values were 95 and 86?%. PET/CT was performed for determining disease spread (n?=?3) and metabolic characterization (n?=?10) of SPNs. Mean SUVmax in the primary pulmonary lesion in TCs and ACs were 2.9?±?0.8 and 7.9?±?5.4, respectively. Nodal involvement (n?=?5) and DM (n?=?3) were also detected. Sensitivity and specificity of PET/CT in the detection of primary tumour, LNs and DM were 85 and 89.4?%, respectively.

Conclusion

SRS is useful in the diagnosis and monitoring of PC tumors when incorporated with ¹⁸FDG PET/CT as a primary staging tool particularly in the determination of disease spread.     

18F-FDG PET of the hands with a dedicated high-resolution PEM system (arthro-PET): correlation with PET/CT,radiography and clinical parameters

Purpose

The aim of this study was to prospectively determine the feasibility and compare the novel use of a positron emission mammography (PEM) scanner with standard PET/CT for evaluating hand osteoarthritis (OA) with ¹⁸F-FDG.

Methods

Institutional review board approval and written informed consent were obtained for this HIPAA-compliant prospective study in which 14 adults referred for oncological ¹⁸F-FDG PET/CT underwent dedicated hand PET/CT followed by arthro-PET using the PEM device. Hand radiographs were obtained and scored for the presence and severity of OA. Summed qualitative and quantitative joint glycolytic scores for each modality were compared with the findings on plain radiography and clinical features.

Results

Eight patients with clinical and/or radiographic evidence of OA comprised the OA group (mean age 73?±?7.7 years). Six patients served as the control group (53.7?±?9.3 years). Arthro-PET quantitative and qualitative joint glycolytic scores were highly correlated with PET/CT findings in the OA patients (r?=?0.86. p??=?0.007; r?=?0.94, p?=?0.001). Qualitative arthro-PET and PET/CT joint scores were significantly higher in the OA patients than in controls (38.7?±?6.6 vs. 32.2?±?0.4, p?=?0.02; 37.5?±?5.4 vs. 32.2?±?0.4, p?=?0.03, respectively). Quantitative arthro-PET and PET/CT maximum SUV-lean joint scores were higher in the OA patients, although they did not reach statistical significance (20.8?±?4.2 vs. 18?±?1.8, p?=?0.13; 22.8?±?5.38 vs. 20.1?±?1.54, p=?0.21). By definition, OA patients had higher radiographic joint scores than controls (30.9?±?31.3 vs. 0, p?=?0.03).

Conclusion

Hand imaging using a small field of view PEM system (arthro-PET) with FDG is feasible, performing comparably to PET/CT in assessing metabolic joint activity. Arthro-PET and PET/CT showed higher joint FDG uptake in OA. Further exploration of arthro-PET in arthritis management is warranted.     

Combined use of 18F-FDG PET/CT and MRI for response monitoring of breast cancer during neoadjuvant chemotherapy

Purpose

To explore the potential complementary value of PET/CT and dynamic contrast-enhanced MRI in predicting pathological response to neoadjuvant chemotherapy (NAC) of breast cancer and the dependency on breast cancer subtype.

Methods

We performed ¹⁸F-FDG PET/CT and MRI examinations before and during NAC. The imaging features evaluated on both examinations included baseline and changes in ¹⁸F-FDG maximum standardized uptake value (SUVmax) on PET/CT, and tumour morphology and contrast uptake kinetics on MRI. The outcome measure was a (near) pathological complete response ((near-)pCR) after surgery. Receiver operating characteristic curves with area under the curve (AUC) were used to evaluate the relationships between patient, tumour and imaging characteristics and tumour responses.

Results

Of 93 patients, 43 achieved a (near-)pCR. The responses varied among the different breast cancer subtypes. On univariate analysis the following variables were significantly associated with (near-)pCR: age (p?=?0.033), breast cancer subtype (p?<?0.001), relative change in SUVmax on PET/CT (p?<?0.001) and relative change in largest tumour diameter on MRI (p?<?0.001). The AUC for the relative reduction in SUVmax on PET/CT was 0.78 (95 % CI 0.68–0.88), and for the relative reduction in tumour diameter at late enhancement on MRI was 0.79 (95 % CI 0.70–0.89). The AUC increased to 0.90 (95 % CI 0.83–0.96) in the final multivariate model with PET/CT, MRI and breast cancer subtype combined (p?=?0.012).

Conclusion

PET/CT and MRI showed comparable value for monitoring response during NAC. Combined use of PET/CT and MRI had complementary potential. Research with more patients is required to further elucidate the dependency on breast cancer subtype.     

Clinical value of 11C-methionine PET/CT in patients with plasma cell malignancy: comparison with 18F-FDG PET/CT

Purpose

PET/CT using FDG has been widely used for the imaging of various malignant tumours, including plasma cell malignancy (PCM), but ¹¹C-methionine (MET), as a radiolabelled amino acid tracer, may also be useful because PCM is able to activate protein synthesis. The purpose of this study was to evaluate the clinical value of PET/CT imaging using MET in PCM, including multiple myeloma, compared with that of FDG PET/CT.

Methods

The study group comprised 20 patients with histologically proven PCM who underwent FDG PET/CT and MET PET/CT scans before (n?=?6) or after (n?=?14) treatment. Semiquantitative analysis was performed on a lesion basis. We also visually evaluated the scans qualitatively using a five-point scale (0, negative; 1, probably negative; 2, equivocal; 3, probably positive; 4, positive) on a lesion and a patient basis. The results were compared between the two scans.

Results

Active PCM was confirmed in 15 patients, including two patients with extramedullary lesions. Uptake of MET tended to be higher (maximum standardized uptake value 10.3 ± 5.6, mean ± SD) than that of FDG (3.4 ± 2.7, p?<?0.001), and more lesions of grade 3 or 4 were depicted by MET (MET 156 lesions vs. FDG 58 lesions). On a patient basis, two patients were accurately diagnosed only by MET. In the remaining 18 patients, consistent results were obtained, but potential upgrade of staging or restaging was necessary in 6 of 11 positive patients because more abnormal lesions were demonstrated by MET. The patient-based sensitivity, specificity and accuracy of MET for restaging were 89 %, 100 % and 93 %, respectively, while those of FDG were 78 %, 100 % and 86 %, respectively.

Conclusion

MET revealed an equal or greater number of lesions in PCM than FDG. MET may be especially useful when negative or inconclusive findings are obtained by FDG despite highly suspicious indications of recurrence.     

Tuberculous lymphadenitis: FDG PET and CT findings in responsive and nonresponsive disease

Purpose

No data is available on the different FDG PET and CT findings in the lymph nodes (LN) of patients with HIV and tuberculosis (TB) who respond compared with those who do not respond to anti-TB treatment by 4?months after initiation of TB treatment. These findings were the focus of our study.

Methods

PET/CT scans performed at 4?months after initiation of TB treatment in 20 consecutive HIV patients were analysed. SUVmax values were obtained for all regions of LN involvement. The diameter of the LNs was measured and the CT enhancement (LNs showing peripheral rim enhancement with central low attenuation, PRECLO, in comparison with homogeneously involved LNs) and the calcification patterns of involved LNs assessed. The relationship between the PET and CT findings and the clinical outcome, response or nonresponse, was evaluated.

Results

FDG PET identified 91 sites of LN involvement, 20 of which were not identified by CT. SUVmax values were significantly higher in nonresponders (8 patients, SUVmax 11.2?±?4.0, mean?±?SD) when compared to responders (12 patients, SUVmax 2.6?±?2.3; p?=?0.0001). In ROC analysis (AUC 0.952) a cut-off value of 4.5 for SUVmax yielded a sensitivity and specificity of 95?% and 85?% for discriminating nonresponding from responding LNs. LNs were significantly larger in nonresponders (1.9?±?0.4?cm) than in responders (1.4?±?0.4?cm; p?=?0.0001); the AUC in the ROC analysis was 0.76. PRECLO LNs were significantly larger (2.2?±?0.3?cm) than homogeneous involved LN basins (1.5?±?0.4?cm) and LN basins with calcification (1.4?±?0.5?cm; p?=?0.001). Using the presence of at least one LN basin with PRECLO as a criterion for nonresponse, responders could be separated from nonresponders with a sensitivity of 88?% and a specificity of 66?%.

Conclusion

LNs responding to TB treatment could be differentiated from nonresponding LNs with a sensitivity and specificity of 95?% and 85?% using a SUVmax cut-off value of 4.5 and a sensitivity and specificity of 88?% and 66?% using the presence of at least one LN basin with PRECLO.     

Detection of underlying malignancy in patients with paraneoplastic neurological syndromes: comparison of 18F-FDG PET/CT and contrast-enhanced CT

Purpose

To determine the value of combined ¹⁸F-FDG PET/CT with diagnostic contrast-enhanced CT (CECT) in detecting primary malignancies and metastases in patients with paraneoplastic neurological syndromes (PNS) and to compare this with CECT alone.

Methods

PET/CT scans from 66 patients with PNS were retrospectively evaluated. Two blinded readers initially reviewed the CECT portion of each PET/CT scan. In a second session 3 months later, the readers analysed the combined PET/CT scans. Findings on each study were assessed using a four-point-scale (1 normal/benign; 2 inconclusive, further diagnostic work-up may be necessary; 3 malignant; 4 inflammatory). Sensitivity and specificity for malignant findings were calculated for PET/CT and CECT. Interreader agreement was determined by calculating Cohen’s kappa. Pooled data from clinical follow-up (including histopathology and follow-up imaging, median follow-up 20.0 months) served as the reference gold standard.

Results

Both readers classified 12 findings in ten patients (15 %) as malignant on the PET/CT scans (two patients had two primary tumours). One such imaging finding (suspected thymic cancer) was false-positive (i.e. benign histology). The most common tumours were bronchial carcinoma (n?=?3), lymph node metastases of gynaecological tumours (n?=?3) and tonsillar carcinoma (n?=?2). Three of 12 findings (25 %) were not detected by CECT alone (cervical carcinoma, lymph node metastasis and tonsillar carcinoma). In a per-patient analysis, sensitivity and specificity for malignant findings were 100 % and 90 % for PET/CT and 78 % and 88 % for CECT. In 24 % (reader 1) and 21 % (reader 2) of the patients, the PET/CT findings were inconclusive. Of these findings, 57 % (reader 1) and 56 % (reader 2) were only diagnosed with PET (e.g. focal FDG uptake of the thyroid, gastrointestinal tract and ovaries). On follow-up, none of these findings corresponded to malignancy. Overall agreement between the two readers was excellent with a Cohen’s kappa of 0.95?±?0.04 (p?<?0.001) for PET/CT and 0.97?±?0.03 (p?<?0.001) for CECT alone.

Conclusion

In this cohort of patients with PNS, PET/CT exhibited improved detection of underlying malignancy versus CECT alone. While hybrid imaging produces a greater number of inconclusive findings, sensitivity is increased for the detection of head and neck and gynaecological malignancies as well as metastatic lymph node involvement.     

Comparison of integrated whole-body [11C]choline PET/MR with PET/CT in patients with prostate cancer

Purpose

To evaluate the performance of conventional [¹¹C]choline PET/CT in comparison to that of simultaneous whole-body PET/MR.

Methods

The study population comprised 32 patients with prostate cancer who underwent a single-injection dual-imaging protocol with PET/CT and subsequent PET/MR. PET/CT scans were performed applying standard clinical protocols (5 min after injection of 793?±?69 MBq [¹¹C]choline, 3 min per bed position, intravenous contrast agent). Subsequently (52?±?15 min after injection) PET/MR was performed (4 min per bed position). PET images were reconstructed iteratively (OSEM 3D), scatter and attenuation correction of emission data and regional allocation of [¹¹C]choline foci were performed using CT data for PET/CT and segmented Dixon MR, T1 and T2 sequences for PET/MR. Image quality of the respective PET scans and PET alignment with the respective morphological imaging modality were compared using a four point scale (0–3). Furthermore, number, location and conspicuity of the detected lesions were evaluated. SUVs for suspicious lesions, lung, liver, spleen, vertebral bone and muscle were compared.

Results

Overall 80 lesions were scored visually in 29 of the 32 patients. There was no significant difference between the two PET scans concerning number or conspicuity of the detected lesions (p not significant). PET/MR with T1 and T2 sequences performed better than PET/CT in anatomical allocation of lesions (2.87?±?0.3 vs. 2.72?±?0.5; p?=?0.005). The quality of PET/CT images (2.97?±?0.2) was better than that of the respective PET scan of the PET/MR (2.69?±?0.5; p?=?0.007). Overall the maximum and mean lesional SUVs exhibited high correlations between PET/CT and PET/MR (ρ?=?0.87 and ρ?=?0.86, respectively; both p?<?0.001).

Conclusion

Despite a substantially later imaging time-point, the performance of simultaneous PET/MR was comparable to that of PET/CT in detecting lesions with increased [¹¹C]choline uptake in patients with prostate cancer. Anatomical allocation of lesions was better with simultaneous PET/MR than with PET/CT, especially in the bone and pelvis. These promising findings suggest that [¹¹C]choline PET/MR might have a diagnostic benefit compared to PET/CT in patients with prostate cancer, and now needs to be further evaluated in prospective trials.     

Diagnostic accuracy of 18F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma

Purpose

To evaluate the diagnostic accuracy of ¹⁸F-FDG PET/CT for detecting recurrence in patients with primary skeletal Ewing sarcoma.

Methods

We retrospectively analysed data from 53 patients (age 20.1?±?10.5 years, 39 male) who had undergone 71 ¹⁸F-FDG PET/CT studies for suspected recurrence (52 studies) or for routine follow-up (19 studies) after primary therapy of skeletal Ewing sarcoma. ¹⁸F-FDG PET/CT studies were evaluated qualitatively and quantitatively (maximum standardized uptake value, SUVmax) by two nuclear medicine physicians in consensus. Sensitivity, specificity, predictive values and accuracy were calculated on per study basis. Clinical/imaging follow-up (minimum 6 months) and/or histopathology (when available) were taken as the reference standard.

Results

Of the total of 71 ¹⁸F-FDG PET/CT studies, 42 (59.1 %) were positive for recurrence and 29 (40.9 %) were negative for recurrence. Local recurrence was most common (38 studies) followed by bone metastasis (9 studies), and node and lung metastasis (2 studies each). Of the 71 studies, 38 were true-positive, 27 were true-negative, 4 were false-positive and 2 were false-negative. Overall per study based sensitivity was 95 %, specificity was 87 %, PPV was 90 %, NPV was 93 % and accuracy was 91.5 %. No significant difference was found in the accuracy of PET/CT between the suspected recurrence group and the routine follow-up group (94 % vs. 84 %; P?=?0.390). Overall mean lesion SUVmax was 7.8?±?4.1 (range 1.9–17.2). No site-based difference was found in SUVmax.

Conclusion

¹⁸F-FDG PET/CT demonstrates high diagnostic accuracy for detecting recurrence in patients with primary skeletal Ewing sarcoma, when it is suspected (clinically or on imaging) or during routine follow-up.     

Evaluation of early response to concomitant chemoradiotherapy by interim 18F-FDG PET/CT imaging in patients with locally advanced oesophageal carcinomas

Purpose

The best way to assess the response to chemoradiotherapy of locally advanced oesophageal carcinomas is not known. We used ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT to evaluate the metabolic response during chemoradiotherapy and tried to correlate this response to survival.

Methods

Patients with biopsy-proven oesophageal carcinoma underwent FDG PET/CT with evaluation of the standardized uptake value (SUV) before any treatment (SUV1) and during chemoradiotherapy after two cycles of 5-fluorouracil (FU)/cisplatin and 20 Gy (SUV2). Metabolic response was defined as 1?(SUV2/SUV1). Surgery was discussed after 40 Gy and three cycles of chemotherapy. Results of interim PET were not considered for the therapeutic decision.

Results

Among 72 patients who underwent a first FDG PET/CT before any treatment, 59 (82 %) could receive the second FDG PET/CT examination. Median survival was 22.2 months with 1-year and 2-year survivals of 70 and 46 %, respectively. Nineteen patients (32 %) underwent surgery. Mean SUV1 and SUV2 were 12.3?±?6.2 and 6?±?4.1, respectively (p?<?0.001). Using a cut-off for metabolic response of 50 %, sensitivity and specificity for survival were 0.7 and 0.58. The 2-year overall survival of good responders was 62 % as compared to 27 % for poor metabolic responders. A multivariate analysis was performed, including T and N stages, surgery, histology and metabolic response: only metabolic response was significantly (p?=?0.009) associated with 2-year survival.

Conclusion

Early evaluation of metabolic response had a great prognostic value and could help identify good responders to chemoradiotherapy.     

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     

Functional testicular evaluation using PET/CT with 18F-fluorodeoxyglucose

Purpose

PET/CT using ¹⁸F-FDG is a well-established diagnostic examination in oncology, cardiology and neurology. The clinical significance of nontumoral testicular uptake of FDG is unknown. Functional testicular imaging may have important clinical applications in the diagnosis and prognosis of male infertility. The aim of this study was to determine the andrological value of a FDG PET/CT in analysing testicular function, by correlating the PET/CT data with the sperm parameters.

Methods

Retrospective analysis of FDG PET/CT in 20 consecutive cancer patients without testicular pathology in whom two semen samples had been obtained for analysis before any chemotherapy. FDG PET/CT parameters were the mean standardized uptake value (SUVmean), used for measuring the intensity of uptake, and the functional testicular volume (FV). For statistical analysis, a Spearman's rank correlation test and a Mann-Whitney test were used.

Results

Of 20 patients (mean age 22?years), 18 had provided two sperm samples for cryopreservation. Sperm concentration was above 20?×?10⁶/ml in 55% of the patients. The intensity of uptake and the FV were correlated with the total sperm count, the sperm concentration and motility (p?p?=?0.036). Normospermic and oligospermic men had significant differences in: (1) mean SUVmean, (2) mean FV, and (3) the difference in intensity of uptake between the testes (p?Conclusion This is the first report on the andrological value of FDG PET/CT in analysing nontumoral testicular function. This pilot study showed a significant correlation between intensity of uptake of FDG and testicular FV with the main sperm parameters. PET/CT with FDG could become a useful new tool in assisted reproductive technologies and other andrological or urological applications.     

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.     

F-18 FDG PET/CT in the evaluation of Takayasu arteritis: An experience from the tropics

Objective

To evaluate the performance parameters of FDG PET/CT in patients with Takayasu arteritis at diagnosis and during immunosuppression.

Methods

Retrospective analysis of 60 FDG PET/CT studies in 51 patients was performed (17 scans at diagnosis out of which 4 had follow-up scans also and 43 scans on immunosuppression). The degree of FDG uptake in the vessels was assessed visually using a 4-point scale and maximum standardized uptake value (SUVmax), SUVratio, extent of vasculitis and association with ESR were calculated.

Results

PET/CT was positive for active vasculitis in all 17 patients at diagnosis. The mean SUVmax and mean SUV ratio of the active areas were 5.1 ± 3.0 and 3.2 ± 1.9, respectively. On immunosuppression, PET scan was positive for active vasculitis in 14/43 (32.5%) scans. The mean SUVmax and mean SUVratio of the active areas were 1.7 ± 2.1 and 0.95 ± 1.2, respectively. There was significant difference between the mean SUVmax and mean SUVratio at diagnosis and on immunosuppression, respectively (P < .01). The median number of vascular segments in each uptake grade group was also statistically different (P < .01) between scans at diagnosis and on immunosuppression. The median ESR level in PET positive scans was 29 mm/hour (2-53), whereas in PET negative scans was 35.5 mm/hour (6-50) and the difference was not statistically significant.

Conclusion

FDG PET/CT showed good sensitivity to detect active vasculitis at diagnosis and during immunosuppression. The change in SUVmax between the successive FDG PET/CT scans may give an objective assessment of response to immunosuppression.