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Purpose: The aim of this study was to assess dual-phase 11C-choline PET/computed tomography (CT) for differentiating benign from malignant lesions in patients with biochemical recurrence of prostate cancer., Materials and Methods: We prospectively studied 56 patients with prostate cancer treated by surgery (n=22) or radiotherapy (n=34) who had hypermetabolic foci on 11C-choline PET/CT determined for biochemical recurrence (prostate-specific antigen 1.23-9.9 ng/ml). We used the dual-phase technique, calculating the standardized uptake value (SUV) for early (SUVearly) and late (SUVdelay) acquisitions and the difference between the two (SUVvariation) to determine whether tracer uptake remained stable or increased (accumulative pattern) or decreased (washout pattern). We used t-tests to compare mean and receiver operating characteristic curve analysis (SUVearly/SUVdelay/SUVvariation vs. benign/malignant)., Results: We identified 106 hypermetabolic foci (34 local, 10 inguinal, 34 infradiaphragmatic, 14 supradiaphragmatic, and 14 in bone). We identified 34 local foci (eight after prostatectomy and 26 after radiotherapy). The eight postsurgical foci had an accumulative pattern and recurrence was confirmed (three histology, five follow-up). Of the 26 postradiotherapy foci, three had a washout pattern and follow-up ruled out recurrence; 23 had an accumulative pattern and recurrence was confirmed (14 histology, nine follow-up). The 10 inguinal foci had a washout pattern and were reactive (three histology, seven follow-up). The 34 infradiaphragmatic foci had an accumulative pattern and were malignant (34 follow-up). Of the 14 supradiaphragmatic foci, the three with a washout pattern were benign (three histology) and the 11 with an accumulative pattern were malignant (11 histology). Of the 14 foci in bone, two had a washout pattern and corresponded with signs of spondyloarthropathy. On the receiver operating characteristic curve analysis, SUVvariation best discriminated benign from malignant lesions [area under the curve (AUC)=0.993], followed by SUVdelay (AUC=0.933) and finally SUVearly (AUC=0.665)., Conclusion: Dual-phase PET/CT with 11C-choline is technically feasible despite this tracer's short physical half-life and is useful for discriminating benign from malignant lesions. SUVvariation accurately discriminated between benign and malignant lesions.

Bone scintigraphy has been used extensively in prostate cancer patients to detect bone involvement. (11)C-choline PET/CT is indicated when a biochemical recurrence is suspected, as this procedure is able to detect local recurrence, lymph-node infiltration, and metastases.In cases where the results of these 2 procedures do not coincide, MRI is then usually performed. (18)F-fluoride may become an alternative to MRI for bone imaging.In our patient series, all bone lesions with (11)C-choline uptake were metastases. (18)F-Fluoride did not increase specificity of (11)C-choline but increased sensitivity of bone scintigraphy. CT helped in the interpretation of osteoarthritis and trauma lesions.

Background and Aim: currently it is recognized the usefulness of 18F-FDG PET in assessing response to therapy with imatinib (Gleevec®) in the gastrointestinal tract sarcomas (GIST). To facilitate the follow-up of these studies is important to know the patterns of metastatic spread. The aim of this paper is to describe patterns observed in the 18F-FDG PET/CT., Method: retrospective study included 29 patients who underwent 18F-FDG PET/CT after being diagnosed with unresectable or metastatic GIST. In total, 87 PET/CT studies were performed (1-6 controls per patient) with a mean time of follow-up 6-36 months. We analyzed the location of the lesions evidenced in PET, CT and fusion. Images were evaluated visually and semiquantitatively (SUV). In cases in which has been considered necessary, additional images have been undertaken: PET delayed imaging, intravenous contrast CT and inspiratory chest CT., Results: the most common primary site was the stomach (41%), small bowel (35%), and rectum (24%). Significant changes in the location of metastatic disease between pre-treatment and the monitoring were observed, with the appearance of more extra-abdominal disease., Conclusions: individualization of protocol studies and interpretation of PET, CT and fused images were required for evaluation of treatment response to imatinib. Hybrid 18F-FDG PET/CT provides an accurate determination of the extent of GIST. While the most common metastatic site is the liver and peritoneum, in the following cases are common extra-abdominal disease.

Objectives: To assess the false-negative (FN) rate of positron emission tomography (PET)-chest computed tomography (CT) scan in clinical non-central cIA and cIB non-small-cell lung cancer (NSCLC) for mediastinal staging., Methods: Between January 2007 and December 2010, 402 patients with potentially operable NSCLC were assessed by thoracic CT scan and 18-fluoro-2-deoxy-d-glucose PET-CT for mediastinal staging and to detect extrathoracic metastases, of which 153 surgically treated patients (79 cIA and 74 cIB cases) were prospectively included in the study. Central tumours were excluded on the basis of CT scan criteria, defined as contact with the intrapulmonary main bronchi, pulmonary artery, pulmonary veins or the origin of the first segmental branches. CT scan was considered negative if lymph nodes were <1 cm at the smaller diameter. 18FDG PET-CT was considered negative when the high maximum standard uptake value (SUVmax) was <2.5. Non-invasive surgical staging was carried out in this group, and curative resection plus systematic mediastinal dissection was performed except in the event of unexpected oncological contraindication., Results: Composite non-invasive staging (CT scan, PET-CT) showed a negative predictive value (NPV) of 92% (CI 83.6-96.8) in the cIA group and 85% (CI 74-92) in the cIB group. There were 6 of 79 (7.6%) false-negatives (FNs) in cIA and 11 of 74 (14.8%) in cIB. Multilevel pN2 were detected in four cases, all of them in the cIB group. The most frequently involved N2 was subcarinal (two cases) in cIA and right lower paratracheal (R4) and seven (five cases) in cIB. Occult (pN2) lymph nodes were more frequent in tumour sizes≥5 cm (pT2b, nine cases, four FNs, P=0.03), pN1, adenocarcinoma [excluding minimally invasive adenocarcinoma (MIA) and lepidic predominant growth (LPA)] (P=0.029) and female patients, but no other risk factors for mediastinal metastases were identified (age, clinical stage, tumour location, central or peripheral, P>0.05). Multilevel pN2 was significantly more frequent in the cIB group (P<0.03). In pT≤1 cm (T1a), NPV was significantly better (NPV=100%, P<0.05) than the other subgroups studied (IA>1 cm and IB)., Conclusions: Composite results for non-invasive mediastinal staging (CT scan, PET-CT) showed 11% of FNs in cI stage (7.6% in non-central cIA and 14.8% in cIB). In tumours≤1 cm, NPV makes surgical staging unnecessary. In women with adenocarcinoma and non-central cIB, however, the high FN rate makes invasive staging necessary, particularly in pT2b to decrease the incidence of unexpected pN2 in thoracotomy.

Aim: The aim of this paper was to prospectively evaluate FDG PET/CT in the assessment of metabolic response to neoadjuvant chemotherapy and correlation with tumor cellularity in locally advanced breast cancer., Methods: Images were acquired with a PET/CT scanner in 50 patients at baseline and after completion of treatment, just before surgery. All findings were confirmed by histopathological analysis. PET/CT quantification (SUVmax) at baseline and after finishing neoadjuvant chemotherapy (4 cycles of epirubicin + cyclophosphamide +/- taxanes) were compared using RECIST criteria and Miller & Payne (M&P) scale., Results: Baseline mean tumor size was 4.4±1.6 cm. Thirty eight patients were considered responders and 12 nonresponders. According to M&P scale, 10 patients had good prognosis (grades 4-5) and 40 patients had bad prognosis (grades 1-3). All patients with grade 5 M&P had no significant postchemotherapy FDG uptake. Patients with bad prognosis had lower SUVmax variation (∆SUVmax) than patients with good prognosis (60.7% vs. 80.5%, P=0.0016). ∆SUVmax was lower in nonresponders than in partial responders according to RECIST criteria (38.9% vs. 67.6%, p<0.001), and was also lower in partial responders than complete responders (67.6% vs. 85.4%, P=0.005). A cut-off ∆SUVmax value of 52% differentiates responders from nonresponders with a sensitivity of 86% and a specificity of 90%. Probability densities of the ∆SUVmax (%) for stable disease (<45), partial (>45 to <82) and complete response (>82) showed an overall accuracy of 78% (Weighted Kappa=0.74)., Conclusion: PET/CT is useful to monitor response to neoadjuvant chemotherapy in locally advanced breast cancer. ∆SUVmax on PET/CT correlates with tumor cellularity after completion of neoadjuvant chemotherapy.

Aim: To analyze the potential improvement of (18)F-fluorodeoxyglucose (FDG) PET/CT using additional delayed images of the liver in operated colorectal cancer., Material and Methods: The study prospectively included 71 patients (22 women, 49 men) with mean age of 65 ± 11 years with clinical, analytic or radiological suspicion of current disease. A whole body PET/CT scan was performed at 60 min. (standard images) and after 2 hr (delayed images) post-injection of 4.07 MBq/Kg of (18)F-FDG. Visual and quantitative SUV analysis of PET/CT findings was done. All findings were confirmed by histopathology and/or at least 6 months follow-up., Results: Thirty-seven out of 71 patients were diagnosed of liver metastases (79 metastases). In 38/71 cases there was extra-hepatic disease in the form of local recurrence (10), abdominopelvic (3) or mediastinal (3) lymph nodes, bone (1) or lung metastases (16) and carcinomatosis (10). Sensitivity and specificity in the diagnosis of liver metastases in a patient-by-patient basis in standard (81% and 91%) and in delayed images (95% y 97%) was calculated. The number of lesions detected in delayed images was significantly higher (66/79) than in standard images (57/79). Sensitivity and specificity for PET/CT in the diagnosis of extra-hepatic disease was 84% and 70%, contributing to the detection of synchronous tumors in 5 patients., Conclusions: PET/CT may be useful in the diagnosis of extra-hepatic disease in suspected recurrence of colorectal cancer. Delayed images on PET/CT may increase the sensitivity to identify liver metastases., (Copyright © 2011 Elsevier España, S.L. y SEMNIM. All rights reserved.)

Objective: To assess the value of intraoperatory radioguided probe detection to guide surgical resection of malignant lesions previously detected by (18)F-FDG PET-CT., Material: Twelve consecutive patients with suspected tumor recurrence detected by (18)F-FDG PET-CT considered resectable were enrolled in the study. Ultrasound guided fine needle aspiration (FNA) before surgery was performed in 6 patients and CT guided biopsy was performed in 1 patient. In 5 patients with accessible lesions, a radioguided occult lesion localization (ROLL) technique was performed after injection of (99m)Tc-colloid (1.7-2.4 mCi) inside the lesion under ultrasound or CT guidance, pre-operatively. Radioguided surgical detection was then carried out 19-24 hours afterwards using the gamma probe. In 7 patients with non-accessible needle lesions or multiple lesions, 9.5-10.5 mCi of (18)F-FDG were injected 3-5 hours before radioguided surgery using a PET-dedicated probe (Gamma locator DXI-GF&E)., Results: ROLL technique: All lesions injected with nanocolloid were resected (6 lesions in 5 patients, 1 patient with 2 lesions), and recurrence was histologically confirmed. PET probe: Fourteen out of 16 hypermetabolic lesions detected on the PET-CT were resected. One cervical and one mediastinal lymph node in different patients could not be excised. Histological recurrence was confirmed in 12 out of 14 lesions. In one patient, the 2 lymph nodes excised were inflammatory., Conclusions: (18)F-FDG PET-CT can be key in deciding surgical approach and appropriate radioguided protocol. When lesions are solitary and easily accessible, ROLL technique seems the method of choice. PET probe is more adequate for less accessible lesions., (Copyright © 2011 Elsevier España, S.L. y SEMNIM. All rights reserved.)

A 70-year-old man with operated colorectal cancer relapsed with a solitary lung metastasis. Dual time-point PET/CT performed at 60' (standard images) and after 2 hours (delayed images) showed focal uptake in the lung nodule. A second uptake in the liver dome was also visualized only in the delayed images. Radiofrequency of the lung metastasis was performed by CT-fluoroscopy guide. A PET/CT 1 month after radiofrequency showed significant reduction of activity in the delayed images, and the uptake at 3 months was virtually normal. A fine-needle biopsy of the liver lesion confirmed the final diagnosis of metastasis from adenocarcinoma.

Objective: To evaluate the incidence of (18)F-FDG focal uptake in the myocardium as well as its correlation with coronary vessel calcifications., Material and Methods: A total of 130 patients who underwent an oncological PET/CT study were reviewed retrospectively. Sixty-five had undergone a myocardial perfusion study because of clinical suspicion of coronary artery disease (group 1). There were no significant differences in age and gender regarding another group of the same series (n=65; group 2). Focal myocardial (18)F-FDG uptake and the presence of coronary vessel calcifications were identified by 2 independent observers., Results: Group 1: in 18 out of 65 patients (28%) focal myocardial (18)F-FDG uptake was identified (5 had 2 foci; total: 23 foci). In 43 out of 65 studies (66%), calcification was identified in the coronary vessels. Group 2: in 6 out of 65 patients (9%) focal myocardial (18)F-FDG uptake was identified (1 had 2 foci; total: 7 foci). In 17 out of 65 studies (26%), calcification was identified in the coronary vessels. Comparative analysis: focal myocardial (18)F-FDG uptake and coronary vessel calcifications were more frequent in the group 1 patients (p<0.01). There was no correlation between the presence of coronary vessel calcifications and focal myocardial (18)F-FDG uptake in individual patients in both groups (group 1: p=0.7; group 2: p=0.163)., Conclusions: PET/CT allows simultaneous assessment of focal myocardial (18)F-FDG uptake and myocardial vessel calcifications. Patients with clinical suspicion of coronary artery disease have a higher incidence of focal myocardial (18)F-FDG uptake and coronary calcifications. However, (18)F-FDG focal uptake is often observed in sites remote from those with calcification., (Copyright © 2010 Elsevier España, S.L. y SEMNIM. All rights reserved.)

Aim: To determine the impact of an additional inspiration CT scan on the conventional ¹⁸F-FDG PET-CT protocol in the detection of small pulmonary nodules., Method: One hundred consecutive patients who presented with one or various nodules were studied. Whole-body PET-CT was performed using Gemini (Philips). CT acquisition parameters were 120 kV/25 mAs, the same as those for the transmission/fusion CT (mild expiration) and inspiratory CT., Results: A total of 188 nodules were detected in the inspiratory CT with sizes between 0.3-3 cm. Non-inspiratory CT did not show 20/188 nodules (10.6%) with sizes between 0.3-1cm, this corresponding to 17 patients. The most frequent localization of non-detectable nodules in non-inspiratory CT was the lower lobes. ¹⁸F-FDG uptake was detected by the PET in 83.9% and 72% of nodules with > 1 cm and between 0.7 and 1cm, respectively. However, only 10.5% of nodules <0.7 cm showed increased metabolic activity., Conclusion: In selected patients, inspiratory CT added to conventional PET-CT significantly improves the detection of small nodules (10.6%), especially in those lesions located in the lower lobes, due to respiratory movements, and may have an impact on patient management., (Copyright © 2010 Elsevier España, S.L. y SEMNIM. All rights reserved.)

Objective: To compare the diagnostic accuracy of PET/CT with (18)F-FDG and (11)C-choline for early detection and localization of recurrent prostate cancer., Material and Methods: Thirty-eight patients with increased PSA levels (0.8-9.5 ng/ml) after radical treatment for prostate cancer (surgery n = 20/radiation therapy n = 18) were included. Ten patients were on hormone therapy. All patients underwent a PET/CT with (11)C-choline and (18)F-FDG, respectively, on the same day. The PET imaging findings were compared with histopathology (n = 10); PSA monitoring (n = 21) and/ or other methods (n = 7)., Results: Focal uptake of (11)C-choline was detected in 26 patients (68%), and focal uptake of (18)F-FDG was detected in 13 patients (34%). The (11)C-choline uptake in 14 patients was suggested local recurrence, whereas this was true in only 4 patients (48%) with (18)F-FDG. Pelvic lymph nodes were detected with (11)C-choline PET/CT in 8 patients and only in 4 patients (50%) with (18)F-FDG. Mediastinal involvement was detected in 5 patients with (11)C-choline and 3 patients (60%) with (18)F-FDG. Focal bone involvement was detected in 3 patients with (11)C-choline and (18)F-FDG. (11)C-choline was able to detect 40% of recurrences in patients with PSA < 1 ng/ml, 50% of recurrences in patients with PSA 1-4 ng/ml and 87% of recurrences with PSA > 4 ng/ml. Sensitivity of (11)C-choline was higher for surgically treated patients, with no significant differences found between patients with and without hormone therapy., Conclusions: (11)C-choline PET/CT was useful for the detection of biochemical recurrence of prostate cancer, with higher yielding as compared to (18)F-FDG. (11)C-choline sensitivity was clearly related to PSA levels, was higher in patients with surgery and did not seem to be modified by hormonal therapy. Disease staging with (11)C-choline showed direct impact for the selection of the most appropriate therapeutic approach.

We present the case of a 57-year old woman diagnosed of papillary thyroid carcinoma and treated with thyroidectomy followed by radioiodine (I-131) on two occasions. Follow-up radioiodine scan showed disease in right cervical region, confirmed by fine needle aspiration (FNA) and treated with lymphadenectomy. Due to thyroglobulin elevation, I-131 scan negative and inconclusive cervical ultrasonography/CT scan, we conducted a CT/PET study that confirmed cervical disease. An additional CT scan that was performed on maximum-inspiration showed four micro-nodules, one of which was not detected by the CT scan on shallow breathing (CT/PET). Post-treatment (I-131) scan confirmed uptake in these localizations. Good fusion between PET and CT images that avoids the errors of attenuation correction, especially in the lung bases, is necessary for correct image interpretation of the CT/PET study. Shallow breathing is necessary in order to obtain optimal image fusion with the CT/PET study, although this is not the best to evaluate pulmonary parenchyma in which an additional inspiratory CT scan improves detection of the pulmonary nodules.

Background and Objective: The aim of this study was to evaluate the role of positron emission tomography/computed tomography (PET/CT) in improving the staging and changing the management of aggressive lymphoma patients in comparison with the conventional imaging modalities (CT, and 67Ga scintigraphy)., Patients and Method: Forty consecutive patients with diffuse large B-cell non Hodgkin lymphoma, were prospectively evaluated. All 40 patients underwent a whole body FDG PET/CT and conventional staging techniques (chest and abdomen CT, 67Ga scintigraphy) were studied before therapy. Sixty minutes after the intravenous administration of 370 MBq FDG, a whole body PET/CT was acquired. We hypothesize that PET/CT improves the diagnostic staging of lymphoma and changes the clinical management of patients., Results: PET/CT and CT were concordant in 28 patients (65%). However, PET/CT detected more lesions than CT in 11 patients (27.5%). Only in one patient, CT revealed more extensive disease than PET/CT. Additional information of PET/CT had lead to a change in staging (upstaging) in 6 patients (15%), in turn leading to a change in treatment strategy in 1 patient. PET/CT and 67Ga scintigraphy were concordant in 23 patients (60.5%). PET/CT detected more lesions than 67Ga scintigraphy in 14 patients (42%). PET/CT results changed staging (upstaging) in 4 patients (15%), leading to a change of treatment strategy in one patient., Conclusions: The impression is that PET/CT detected more lesions than conventional examination, but this rarely translates into changes of staging and treatment strategy in aggressive lymphoma.

We present the case of a 34-year-old woman diagnosed of an adenosquamous carcinoma of the uterine cervix, stage IIB of the FIGO classification (International Federation of Gynecology and Obstetrics), treated with quimiotherapy, radiotheraphy and brachytheraphy with posterior hysterectomy. A recurrence of the disease was suspected due to the progressive rise of CEA levels. A PET/CT revealed abnormal foci in both ovaries, that had been transposed to avoid lesions due to radiation, and in a left para-aortic adenopathy. The diagnosis of recurrence in these sites was confirmed by biopsy. PET with FDG (F18-fluorodeoxyglucose) is useful in the staging of primary tumour and in the detection of recurrence in uterine cervical carcinoma, with better sensitivity and specificity than CT and MRI. PET/CT improves anatomic resolution and helps to resolve the origin of unclear foci like in the case presented in which ovaries were not in their normal situation due to transposition.