Impact of 18F-FDG PET/CT on the management of adrenocortical carcinoma: analysis of 106 patients

Purpose

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy. Limited data are available about on value of ¹⁸F-FDG PET/CT in ACC. We evaluated the impact of PET/CT on the management of ACC.

Methods

We performed a retrospective review in patients with ACC who had undergone PET/CT. The impact of PET/CT on the management plan was evaluated by comparing the findings on PET/CT to the findings on contrast-enhanced CT. The sensitivity, specificity, and accuracy of each form of imaging were calculated. The correlations between PET/CT parameters, including maximum standardized uptake value (SUV_max), total lesion glycolysis, and decline in SUV_max after chemotherapy, and clinical outcome were evaluated.

Results

Included in the analysis were 106 patients with 180 PET/CT scans. Of the 106 patients, 7 underwent PET/CT only for initial staging, 84 underwent PET/CT only for restaging, and 15 underwent PET/CT for both initial staging and restaging. PET/CT changed the management plan in 1 of 22 patients (5 %) at initial staging and 9 of 99 patients (9 %) at restaging. In 5 of the patients in whom PET/CT changed the management plan, PET/CT showed response to chemotherapy but contrast-enhanced CT showed stable disease. Sensitivity, specificity, and accuracy were 100 %, 100 %, and 100 % for PET/CT at initial staging; 92.6 %, 100 %, and 96.4 % for CT at initial staging; 98.4 %, 100 %, and 99.5 % for PET/CT at restaging; and 96.8 %, 98.6 %, and 98.0 % for CT at restaging, respectively. No PET/CT parameters were associated with survival at either initial diagnosis or recurrence.

Conclusion

PET/CT findings could substantially change the management plan in a small proportion of patients with ACC. Although lesion detection was similar between PET/CT and CT, PET/CT may be preferred for chemotherapeutic response assessment because it may predict response before anatomic changes are detected on CT.     

Comparison of choline-PET/CT,MRI, SPECT,and bone scintigraphy in the diagnosis of bone metastases in patients with prostate cancer: a meta-analysis

Published data on the diagnosis of bone metastases of prostate cancer are conflicting and heterogeneous. We performed a comprehensive meta-analysis to compare the diagnostic performance of choline-PET/CT, MRI, bone SPECT, and bone scintigraphy (BS) in detecting bone metastases in parents with prostate cancer. Pooled sensitivity, specificity, and diagnostic odds ratios (DOR) were calculated both on a per-patient basis and on a per-lesion basis. Summary receiver operating characteristic (SROC) curves were also drawn to obtain the area under curve (AUC) and Q* value. Sixteen articles consisting of 27 studies were included in the analysis. On a per-patient basis, the pooled sensitivities by using choline PET/CT, MRI, and BS were 0.91 [95 % confidence interval (CI): 0.83–0.96], 0.97 (95 % CI: 0.91–0.99), 0.79 (95 % CI: 0.73–0.83), respectively. The pooled specificities for detection of bone metastases using choline PET/CT, MRI, and BS, were 0.99 (95 % CI: 0.93–1.00), 0.95 (95 % CI: 0.90–0.97), and 0.82 (95 % CI: 0.78–0.85), respectively. On a per-lesion basis, the pooled sensitivities of choline PET/CT, bone SPECT, and BS were 0.84 (95 % CI: 0.81–0.87), 0.90 (95 % CI: 0.86–0.93), 0.59 (95 % CI: 0.55–0.63), respectively. The pooled specificities were 0.93 (95 % CI: 0.89–0.96) for choline PET/CT, 0.85 (95 % CI: 0.80–0.90) for bone SPECT, and 0.75 (95 % CI: 0.71–0.79) for BS. This meta-analysis indicated that MRI was better than choline PET/CT and BS on a per-patient basis. On a per-lesion analysis, choline PET/CT with the highest DOR and Q* was better than bone SPECT and BS for detecting bone metastases from prostate cancer.     

Perfusion-metabolism coupling in recurrent gliomas: a prospective validation study with 13N-ammonia and 18F-fluorodeoxyglucose PET/CT

Introduction

We assessed the validity of “perfusion-metabolism coupling” hypothesis in recurrent glioma with ¹³N-ammonia (¹³N-NH₃) PET/CT and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET/CT.

Methods

Fifty-six consecutive patients (age, 38.8?±?12.1 years; 62.5 % males) with histologically proven and previously treated glioma presenting with clinical suspicion of recurrence were prospectively enrolled and evaluated with ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT. PET/CT images were evaluated both qualitatively and semiquantitatively. Tumor to white matter uptake ratio (T/W) and tumor to gray matter uptake ratio (T/G) were calculated and analyzed for both the modalities. A combination of clinico-radiological follow-up, repeated imaging, and biopsy (when available) were considered as the reference standard.

Results

Based on the reference standard, 27/56 patients had recurrence. ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT were concordant in 55/56 patients. Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ¹³N-NH₃PET/CT were 77.8, 86.2, 84.0, 80.7, and 82.1 %, respectively, and for ¹⁸F-FDG PET/CT were 77.8, 89.7, 87.5, 81.2, and 83.9 %, respectively. There was excellent agreement between results of ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT (??=?0.964; P?13N-NH₃ PET/CT and ¹⁸F-FDG PET/CT were not significantly different between high-grade and low-grade glioma (P?=?1.000). A strong positive correlation was noted between the uptake ratios derived on the two modalities (ρ?=?0.866, P?ρ?=?0.918, P?Conclusion A combination of ¹³N-NH₃ PET/CT and ¹⁸F-FDG PET/CT demonstrates that perfusion and metabolism are coupled in recurrent gliomas. These tracers target two different but interrelated aspects of the same pathologic process and can be used as surrogates for each other.     

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.     

18F-Fluorocholine PET/CT for localization of hyperfunctioning parathyroid tissue in primary hyperparathyroidism: a pilot study

Purpose

Primary hyperparathyroidism is a common endocrine disorder which is diagnosed biochemically and for which therapy is surgical. A prerequisite for minimally invasive surgery, which minimizes morbidity and cost, is accurate localization of the involved gland(s). The aim of this study was to evaluate the usefulness of ¹⁸F-fluorocholine PET/CT for preoperative localization of hyperfunctioning parathyroid tissue.

Methods

¹⁸F-Fluorocholine PET/CT and conventional parathyroid scintigraphic imaging consisting of ^99mTc-sestaMIBI SPECT/CT, ^99mTc-sestaMIBI dual-phase imaging and ^99mTc-sestaMIBI/pertechnetate subtraction imaging were performed in 24 patients. The diagnostic performance of the imaging methods was compared against histology as the gold standard and postoperative serum Ca²⁺ and iPTH values.

Results

The sensitivity and specificity of ¹⁸F-fluorocholine PET/CT were 92 % and 100 %, respectively, in contrast to 49 % and 100 %, 46 % and 100 %, and 44 % and 100 % for ^99mTc-sestaMIBI SPECT/CT, ^99mTc-sestaMIBI/pertechnetate subtraction imaging and ^99mTc-sestaMIBI dual-phase imaging, respectively. Combined conventional scintigraphic imaging had a sensitivity and specificity of 64 % and 100 %, respectively. The performance of ¹⁸F-fluorocholine PET/CT was superior particularly in patients with multiple lesions or hyperplasia.

Conclusion

¹⁸F-Fluorocholine PET/CT appears to be a promising, effective imaging method for localization of hyperfunctioning parathyroid tissue.     

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.     

Performance of intra-procedural 18-fluorodeoxyglucose PET/CT-guided biopsies for lesions suspected of malignancy but poorly visualized with other modalities

Purpose

We sought to evaluate the safety and the diagnostic success rate of percutaneous biopsies performed under intra-procedural ¹⁸?F-deoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) guidance for lesions difficult to see with conventional cross-sectional imaging.

Methods

From 2011 to 2013, consecutive clinically indicated percutaneous PET/CT-guided biopsies of 106 masses (mean size, 3.3 cm; range, 0.7–15.9 cm; SD, 2.9 cm) in bones (n?=?33), liver (n?=?26), soft tissues (n?=?18), lung (n?=?15) and abdomen (n?=?14) were reviewed. The biopsy procedures were performed following injection of a mean of 255 MBq (SD, 74) FDG. Mean maximal standardized uptake value (SUV) of lesions was 8.8 (SD, 6.3). A systematic review of the histopathological results and outcomes was performed.

Results

Biopsies were positive for malignancy in 76 cases (71.7 %, 76/106) and for benign tissue in 30 cases (28.3 %, 30/106). Immediate results were considered adequate for 100 PET/CT biopsies (94.3 %, 100/106) requiring no further exploration, and for the six others (5.7 %, 6/106) benign diagnoses were confirmed after surgery (n?=?4) or follow-up (n?=?2). The consequent overall sensitivity and the diagnostic success of biopsy were therefore 100 %. No significant differences in terms of detection of malignancy were observed between the different locations. Lesions > 2 cm or with SUV?>?4 were not significantly more likely to be malignant. Complications occurred after four biopsies (3.7 %, 4/106).

Conclusion

Intra-procedural PET/CT guidance appears as a safe and effective method and allows high diagnostic success of percutaneous biopsies for metabolically active lesions.     

Impact of 11C-choline PET/CT on clinical decision making in recurrent prostate cancer: results from a retrospective two-centre trial

Purpose

The aim of this retrospective two-centre study was to investigate the clinical impact of ¹¹C-choline PET/CT on treatment management decisions in patients with recurrent prostate cancer (rPCa) after radical therapy.

Methods

Enrolled in this retrospective study were 150 patients (95 from Bologna, 55 from Würzburg) with rPCa and biochemical relapse (PSA mean?±?SD 4.3?±?5.5 ng/mL, range 0.2–39.4 ng/mL) after radical therapy. The intended treatment before PET/CT was salvage radiotherapy of the prostatic bed in 95 patients and palliative androgen deprivation therapy (ADT) in 55 patients. The effective clinical impact of ¹¹C-choline PET/CT was rated as major (change in therapeutic approach), minor (same treatment, but modified therapeutic strategy) or none. Multivariate binary logistic regression analysis included PSA level, PSA kinetics, ongoing ADT, Gleason score, TNM, age and time to relapse.

Results

Changes in therapy after ¹¹C-choline PET/CT were implemented in 70 of the 150 patients (46.7 %). A major clinical impact was observed in 27 patients (18 %) and a minor clinical impact in 43 (28.7 %). ¹¹C-choline PET/CT was positive in 109 patients (72.7 %) detecting local relapse (prostate bed and/or iliac lymph nodes and/or pararectal lymph nodes) in 64 patients (42.7 %). Distant relapse (paraaortic and/or retroperitoneal lymph nodes and/or bone lesions) was seen in 31 patients (20.7 %), and both local and distant relapse in 14 (9.3 %). A significant difference was observed in PSA level and PSA kinetics between PET-positive and PET-negative patients (p?p?p?>?0.05). In both centres the same criteria to validate PET-positive findings were used: in 17.3 % of patients by histology and in 82.7 % of patients by correlative imaging and/or clinical follow-up (follow-up mean 20.5 months, median 18.3 months, range 6.2–60 months).

Conclusion

¹¹C-Choline PET/CT had a significant impact on therapeutic management in rPCa patients. It led to an overall change in 46.7 % of patients, with a major clinical change implemented in 18 % of patients. Further prospective studies are needed to evaluate the effect of such treatment changes on patient survival.     

68Ga-DOTATATE PET/CT in the evaluation of patients with neuroendocrine metastatic carcinoma of unknown origin

Objective

There is little evidence regarding the role of ⁶⁸Ga-DOTATATE PET/CT for the identification of primary tumors in patients with metastatic neuroendocrine carcinoma of unknown primary. The aim of this study is to assess the value of this technique in the mentioned clinical scenario.

Methods

We retrospectively studied twenty-nine patients (mean age 59.5 ± 10.6 years; female 17) with pathologically proven neuroendocrine metastases. In all cases conventional imaging was negative for primary tumor identification. ⁶⁸Ga-DOTATATE PET/CT was performed with a mean dose of 104.2 ± 18.8 MBq, using a 64-slice PET/CT with time-of-flight correction. A team of an experienced radiologist and a nuclear medicine physician evaluated the images. The maximum SUV (SUVm) was measured in all abnormal foci. Histopathology (when available) and/or clinical follow-up with correlative imaging was considered as reference standard.

Results

⁶⁸Ga-DOTATATE PET/CT identified the primary tumor in 17/29 (59 %) patients in the following locations: pancreas (n = 7), ileum (n = 7), duodenum (n = 1), colon (n = 1) and stomach (n = 1). In this population a significant correlation was found between SUVm of primary tumor and metastases (r = 0.815, P < 0.0001). Furthermore, additional sites of unsuspected metastases were demonstrated in 9 patients of this group and in 6 patients in whom no primary tumor was localized, mainly in lymph nodes and mesentery. Pathology confirmation was obtained in 7 patients who underwent surgery, whereas in the remaining 10 patients, correlative imaging and follow-up confirmed primary tumor localization.

Conclusions

⁶⁸Ga-DOTATATE PET/CT is a clinically useful imaging technique for the localization of primary tumors in patients with neuroendocrine metastatic carcinoma of unknown origin with the potential of having a significant impact in patient management and therapy planning.     

11C-Choline PET/pathology image coregistration in primary localized prostate cancer

Purpose

The aim of this study was to develop a methodology for the comparison of pathology specimens after prostatectomy (post-S) with PET images obtained before surgery (pre-S). This method was used to evaluate the merit of ¹¹C-choline PET/CT for delineation of gross tumour volume (GTV) in prostate cancer (PC).

Methods

In 28 PC patients, ¹¹C-choline PET/CT was performed before surgery. PET/CT data were coregistered with the pathology specimens. GTV on PET images (GTV-PET) was outlined automatically and corrected manually. Tumour volume in the prostate (TVP) was delineated manually on the pathology specimens. Based on the coregistered PET/pathology images, the following parameters were assessed: SUVmax and SUVmean in the tumoral and nontumoral prostate (NP), GTV-PET (millilitres) and TVP (millilitres).

Results

PET/pathology image coregistration was satisfactory. Mean SUVmax in the TVP was lower than in the NP: 5.0 and 5.5, respectively (p?=?0.093). Considering the entire prostate, SUVmax was located in the TVP in two patients, in the TVP and NP in 12 patients and exclusively in NP in 14 patients. Partial overlap the TVP and GTV-PET was seen in 71 % of patients, and complete overlap in 4 %.

Conclusion

PET/pathology image coregistration can be used for evaluation of different imaging modalities. ¹¹C-Choline PET failed to distinguish tumour from nontumour tissue.     

Diagnostic Value of 68Ga-DOTATATE PET/CT in Liver Metastases of Neuroendocrine Tumours of Unknown Origin

Purpose

In neuroendocrine liver metastases of unknown primary, a multimodality approach is usually adopted and consists of transabdominal ultrasound, endoscopic ultrasound (EUS), computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine techniques, endoscopy and exploratory surgery. The purpose of the study is to evaluate the diagnostic value of ⁶⁸Ga-DOTATATE positron emission tomography (PET)/CT as part of a multimodality approach in neuroendocrine liver metastases of unknown primary.

Materials and Methods

Six patients (M:F?=?5:1, age range 28–56 years) with immunohistochemically proven neuroendocrine liver metastases but inconclusive initial CT work-up were retrospectively analysed. Clinical finding, histopathology, comparative imaging and follow-up were used to validate the results when ethically justified.

Results

⁶⁸Ga-DOTATATE PET/CT identified the primary tumour in five out of six (83.3 %) patients: pancreas (n?=?4) and stomach (n?=?1). Out of three patients with indeterminate primary on initial CT, two patients were confirmed by ⁶⁸Ga-DOTATATE PET/CT. Absence of uptake in indeterminate primary of one patient was later confirmed negative by histopathology. In another three patients with undetected primary on initial CT, primary site was demonstrated in all patients with unsuspected metastases in two patients on ⁶⁸Ga-DOTATATE PET/ CT. No further work-up was done to confirm the primary in patients with distant metastases. Change of management was observed in three out of six (50 %) patients.

Conclusion

Our small study indicates that ⁶⁸Ga-DOTATATE PET/CT is a promising diagnostic option in the multimodality approach to neuroendocrine liver metastases of unknown primary origin.     

Prone-position acquisition of myocardial 123I-metaiodobenzylguanidine (MIBG) SPECT reveals regional uptake similar to that found using 11C-hydroxyephedrine PET/CT

Objectives

¹²³I-metaiodobenzylguanidine (MIBG) has been used to estimate cardiac sympathetic nervous innervation. Heterogeneous MIBG distribution is mainly associated with high physiological MIBG uptakes in the liver. We postulate that prone position acquisition might be especially effective for MIBG, providing for separation from high liver uptake similar to that provided by perfusion single-photon emission computed tomography (SPECT). We investigated whether prone-position acquisition improved MIBG image quality by comparing our results to those acquired using supine MIBG and high-quality ¹¹C-hydroxyephedrine (HED) positron emission tomography/computed tomography PET/CT.

Methods

Ten male volunteers (body mass index (BMI) 22.7 ± 3.4) underwent prone and supine MIBG and HED PET. Relative regional tracer uptake was estimated in early MIBG and HED. Acquired images were divided into 17 segments and were grouped into 4 regions: anterior, inferior, septum, and lateral. For each patient, the inferior/anterior ratio was calculated.

Results

The quality of images acquired using prone MIBG was better than that using supine MIBG (p < 0.05). Inferior and septum relative MIBG uptake was reduced in comparison with anterior or lateral MIBG uptake in the supine position (inferior vs. anterior: 69.0 ± 5.6 vs. 82.3 ± 4.6 %, p < 0.01; septum vs. lateral: 66.2 ± 5.1 vs. 81.9 ± 5.4 %, p < 0.01). Prone MIBG showed a significantly higher inferior/anterior uptake ratio in comparison with supine MIBG (n = 24, seg: 92.2 ± 7.2 vs. 83.6 ± 5.7 %, p < 0.05). However, intergroup differences in uptake ratio were demonstrated among prone and supine MIBG and HED. HED PET/CT still showed a higher uptake ratio in comparison with prone MIBG SPECT (103.9 ± 8.0 vs. 92.2 ± 7.2 %, p < 0.05).

Conclusion

Even in normal male subjects, standard supine MIBG imaging showed reduced inferior and septum uptake. Uptake with prone MIBG imaging showed a significant improvement over that with supine imaging and was closer to uptake for HED PET/CT. This improvement may be the result of preventing intense uptake by the liver. Prone data acquisition may be a viable alternative in evaluating regional abnormalities using MIBG SPECT in men.     

Comparison of CT-Guided Percutaneous Biopsy with and Without Registration of Prior PET/CT Images to Diagnose Mediastinal Tumors

Purpose

To compare computed tomography (CT)-guided percutaneous biopsy with and without registration of prior positron emission tomography (PET)/CT images in the diagnosis of mediastinal tumors.

Methods

We performed clinically indicated percutaneous biopsy in 106 patients with mediastinal tumors in the anterior (n = 61), posterior (n = 21), middle (n = 16), and superior mediastinum (n = 8). The final diagnosis was based on surgical outcomes, or imaging findings and the results of at least 6-month follow-up. The patients underwent CT-guided percutaneous biopsy with (group 1, n = 56) or without (group 2, n = 50) registration of prior PET/CT images obtained no more than 22 days earlier. The registered images were used to plan the procedure and help target the tumors.

Results

CT-guided percutaneous needle biopsy yielded adequate samples in 101 of 106 (95 %) patients (group 1, n = 53; group 2, n = 48); in 95 patients (94 %), the diagnosis was confirmed by specific histological typing (group 1, n = 51; group 2, n = 44). The diagnostic accuracy of CT-guided percutaneous biopsy with and without the registration of prior PET/CT images was not statistically different (group 1, 96 %; group 2, 93 %, p = 0.324).

Conclusion

CT-guided percutaneous biopsy is an easy and safe procedure that can provide a precise diagnosis in the majority of mediastinal tumors. PET/CT-guided biopsy yielded no special diagnostic advantages.     

Inferior glucose metabolism and chemosensitivity of post-radiotherapy local recurrence in comparison with distant metastases as assessed by sequential 18F-FDG PET/CT imaging

Purpose

To compare glucose metabolism and chemosensitivity between recurrence within the irradiation field and metastases outside the irradiation field in the same patient using ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography images (PET/CT).

Methods

The ¹⁸F-FDG PET/CT images of 43 cancer patients with both local recurrence (in-field) and distal metastases (out-field) after initial treatments were reviewed. 23 patients after definitive radiotherapy/chemoradiotherapy and 20 patients after radical surgery were assigned to a radiation group and surgery group, respectively. The tumor maximal diameter on CT and PET images (D _CT and D _PET), maximal SUV (SUV_max), and mean SUV (SUV_mean) were measured. All the patients were administered chemotherapy, and 17 patients from the radiation group and 10 patients from the surgery group underwent PET/CT scanning within 1–2 months after the treatment. The changes in D _CT, D _PET, SUV_max and SUV_mean for each lesion were calculated and compared between in-field and out-field tumors for both groups.

Results

In the surgery group, no significant difference was found in tumor size or FDG uptake between the local recurrence and metastases. In the radiation group, both SUV_max (7.03 ± 3.48) and SUV_mean (4.33 ± 1.67) of the in-field tumors were lower than those (8.45 ± 4.34 and 5.36 ± 2.51, respectively, P < 0.05) of out-field tumors. Moreover, the response extent of in-field tumors was lower than that of out-field tumors in the radiation group (P < 0.05). However, in the surgery group, there was no difference in the response extent (tumor size and SUVs) between the local recurrence and metastases (P > 0.05).

Conclusion

The recurrence within the irradiation field and metastases outside the irradiation field in the same patient do not share the same biological characteristics or treatment response, with inferior glucose metabolism and chemosensitivity seen in locally recurrent tumors.     

Performance of 18F-FDG PET/CT as a postoperative surveillance imaging modality for asymptomatic advanced gastric cancer patients

Objective

The purpose of this study was to investigate the diagnostic performance of postoperative fluorine-18 fluoro-2-deoxy-d-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) as a surveillance modality for advanced gastric cancer patients who were asymptomatic and negative by conventional follow-up.

Methods

We retrospectively collected 46 advanced gastric cancer patients who received approximately 1-year-postoperative ¹⁸F-FDG PET/CT surveillance following curative resection (mean age 60.6 ± 11.5 years). ¹⁸F-FDG PET/CT was interpreted by nuclear medicine physicians who were blind to the clinical information. Final confirmation was determined by clinical follow-up using tumor markers, conventional CT scan, upper gastrointestinal endoscopy and with/without subsequent histopathologic diagnosis.

Results

Four patients developed recurrence (8.7 %; 1 local and 3 distant recurrences). For local recurrence, ¹⁸F-FDG PET/CT found four hypermetabolic lesions and one was local recurrence. For distant recurrence, seven hypermetabolic lesions were found in six patients and true-positive was three lesions. False-positive cases were mainly turned out to be physiologic small bowel uptake. Regardless of the recurrence site, the sensitivity, specificity, positive predictive value and negative predictive value of ¹⁸F-FDG PET/CT were 100 % (4/4, 95 % confidence interval (CI) 39.6–100 %), 88.1 % (37/42, 95 % CI 73.6–95.5 %), 44.4 % (4/9, 95 % CI 15.3–77.3 %) and 100 % (37/37, 95 % CI 88.3–100 %), respectively in the patient-based analysis.

Conclusion

Our study showed good specificity of postoperative surveillance ¹⁸F-FDG PET/CT for detecting recurrence. Careful caution should be made for interpreting some false-positive hypermetabolic lesions in postoperative ¹⁸F-FDG PET/CT, especially at the local anastomosis site.     

18F-FDG PET-CT uptake is a feature of both normal diameter and aneurysmal aortic wall and is not related to aneurysm size

Purpose

Aortic metabolic activity is suggested to correlate with presence and progression of aneurysmal disease, but has been inadequately studied. This study investigates the 2-[¹⁸F] fluoro-2-deoxy-D-glucose (¹⁸F-FDG) uptake in a population of infra-renal abdominal aortic aneurysms (AAA), compared to a matched non-aneurysmal control group.

Methods

The Positron Emission Tomography – Computed Tomography (PET/CT) database was searched for infra-renal AAA. Exclusion criteria were prior repair, vasculitis, and saccular/mycotic thoracic or thoraco-abdominal aneurysms. Matching of 159 non-aneurysmal (<3 cm diameter) controls from the same population was assessed. Infra-renal aortic wall FDG uptake was assessed using visual analysis; maximum standardized uptake value (SUV_max) and target to background mediastinal blood pool ratio (TBR) were documented. Predictors of FDG uptake (age, sex, aortic diameter, hypertension, statin use, and diabetes) were assessed using univariate analysis. Follow-up questionnaires were sent to referring clinicians.

Results

Aneurysms (n?=?151) and controls (n?=?159) were matched (p?>?0.05) for age, sex, diabetes, hypertension, smoking status, statin use, and indication for PET/CT. Median aneurysm diameter was 5.0 cm (range 3.2–10.4). On visual analysis there was no significant difference in the overall numbers with increased visual uptake 24 % (36/151) in the aneurysm group vs. 19 % (30/159) in the controls, p?=?ns. SUV_max was slightly lower in the aneurysm group vs. controls (mean (2 SD) 1.75(0.79) vs. 1.84(0.58), p?=?0.02). However there was no difference in TBR between the AAA group and controls (mean (2 SD) 1.03 (0.46) vs. 1.05(0.31), p?=?0.36). During a median 18 (interquartile range 8–35) months’ follow-up 20 were repaired and four were confirmed ruptured.

Conclusions

The level of metabolic activity as assessed by ¹⁸F-FDG PET/CT in infra-renal AAA does not correlate with aortic size and does not differ between aneurysms and matched controls.     

Furosemide diminishes 18F-fluoroethylcholine uptake in prostate cancer in vivo

Purpose

¹⁸F-Fluoroethylcholine (¹⁸F-FECh) is excreted via the urinary system with high activity accumulation in the urinary bladder. Furosemide and oral hydration can be administered concomitantly to reduce urinary activity to provide better detectability of retroperitoneal and pelvic lesions. Currently it is unknown if there is any effect of furosemide on ¹⁸F-FECh uptake in organs, tissues and tumour lesions and the extent to which image quality along the urinary tract may be improved by furosemide.

Methods

We retrospectively analysed 217 ¹⁸F-FECh PET/CT examinations from 213 patients with known prostate cancer (PCa), performed either with oral hydration (109) or furosemide 20 mg together with oral hydration (108). Maximum ¹⁸F-FECh uptake in different organs, tissues, lymph nodes and osseous metastases was quantified in terms of standardized uptake value (SUV) in a volume of interest and compared between the two groups. To characterize the impact of furosemide on lesion detectability a three-point rating scale was used to assess the presence of focal activity spots in the ureters and of perivesicular artefacts.

Results

Patient characteristics and distribution of tumour lesions were well balanced between the two groups. Overall, SUVmax values from normal organs were increased after furosemide compared to the values in patients scanned without furosemide. Significant changes were observed in the salivary glands, liver, spleen, pancreas, kidneys, gluteus muscle and perirenal fat. SUVmax values were significantly decreased after furosemide in lymph node metastases (SUVmax 4.81?±?2.68 vs. 6.48?±?4.22, p?=?0.0006), but not in osseous metastases. Evaluation of image quality along the urinary tract revealed significantly better depiction of the perivesicular space and significantly less focal tracer accumulation in the ureters in patients receiving furosemide, but the number of detected lymph nodes was not significantly different.

Conclusion

Furosemide administration reduced choline uptake in tumour lesions, especially significant in pelvic lymph node metastases. Although furosemide administration improved image quality, optimal image quality may also be obtained by adequate hydration without the risk of diminishing choline uptake in PCa lesions. Therefore a controlled hydration protocol seems more appropriate than administration of furosemide.     

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.     

Performance of FDG PET/CT at initial diagnosis in a rare lymphoma: nodular lymphocyte-predominant Hodgkin lymphoma

Purpose

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare Hodgkin lymphoma distinguished from classical Hodgkin lymphoma (cHL) by the nature of the neoplastic cells which express B-cell markers. We wanted to determine the diagnostic performance of FDG PET/CT in initial assessment and its therapeutic impact on staging.

Methods

We retrospectively studied a population of 35 patients with NLPHL (8 previously treated for NLHPL, 27 untreated). All patients underwent an initial staging by pretherapeutic FDG PET/CT. The impact on initial stage or relapse stage was assessed by an independent physician.

Results

In a per-patient analysis, the sensitivity of the pretherapeutic FDG PET/CT was 100 %. In a per-site analysis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of pretherapeutic FDG PET/CT were 100 %, 99 %, 97 %, 100 % and 99 %, respectively. Pretherapeutic FDG PET/CT led to a change in the initial stage/relapse stage in 12 of the 35 patients (34 %). In contrast to previous results established without FDG PET/CT, 20 % of patient had osteomedullary lesions.

Conclusion

Pretherapeutic FDG PET/CT has excellent performance for initial staging or relapse staging of NLPHL.     

Role of [18F]FDG PET in prediction of KRAS and EGFR mutation status in patients with advanced non-small-cell lung cancer

Purpose

The tumour molecular profile predicts the activity of epidermal growth factor receptor (EGFR) inhibitors in non-small-cell lung cancer (NSCLC). However, tissue availability and tumour heterogeneity limit its assessment. We evaluated whether [¹⁸F]FDG PET might help predict KRAS and EFGR mutation status in NSCLC.

Methods

Between January 2005 and October 2011, 340 NSCLC patients were tested for KRAS and EGFR mutation status. We identified patients with stage III and IV disease who had undergone [¹⁸F]FDG PET/CT scanning for initial staging. SUVpeak, SUVmax and SUVmean of the single hottest tumour lesions were calculated, and their association with KRAS and EGFR mutation status was assessed. A receiver operator characteristic (ROC) curve analysis and a multivariate analysis (including SUVmean, gender, age and AJCC stage) were performed to identify the potential value of [¹⁸F]FDG PET/CT for predicting KRAS mutation.

Results

From 102 patients staged using [¹⁸F]FDG PET/CT, 28 (27 %) had KRAS mutation (KRAS+), 22 (22 %) had EGFR mutation (EGFR+) and 52 (51 %) had wild-type KRAS and EGFR profiles (WT). KRAS+ patients showed significantly higher [¹⁸F]FDG uptake than EGFR+ and WT patients (SUVmean 9.5, 5.7 and 6.6, respectively; p?18F]FDG uptake between EGFR+ patients and WT patients. ROC curve analysis for KRAS mutation status discrimination yielded an area under the curve of 0.740 for SUVmean (p?Conclusion NSCLC patients with tumours harbouring KRAS mutations showed significantly higher [¹⁸F]FDG uptake than WT patients, as assessed in terms of SUVpeak, SUVmax and SUVmean. A multivariate model based on age, gender, AJCC stage and SUVmean might be used as a predictive marker of KRAS mutation status in patients with stage III or IV NSCLC.