Combined Positron Emission Tomography-computed Tomography Research Articles

Utility of PET-CT in Newly Diagnosed HPV-Associated Oropharyngeal Squamous Cell Carcinoma.

To compare the utility of positron emission tomography-computed tomography (PET-CT) versus contrasted CT neck combined with routine chest imaging for disease staging and treatment planning in human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) with clinically evident sites of primary disease. All adult patients with primary HPV-associated OPSCC at a single quaternary care cancer center from 2018 to 2019 were reviewed, and those with images available for re-review were included. Primary outcomes included concordance in clinical staging between the 2 imaging modalities of interest (PET-CT vs CT), as well as independent agreement of each with pathologic staging. Analysis was performed via ordinal logistic regression. A secondary outcome was treatment selection after diagnostic imaging, analyzed via chi-squared testing. In total, 100 patients were included for evaluation, of which 89% were male, 91% Caucasian, and mean age was 61.2 years (SD 9.6). Clinical disease staging agreed between imaging modalities in 95% of cases (54 of 57 patients). Pathologic staging agreed with clinical staging from CT neck in 93% of cases (25 of 27 patients; P = .004), and with PET-CT in 82% (14 of 17 patients; P =.003). No differences were observed between the 2 imaging modalities for subsequent treatment selection (P = .39). In uncomplicated HPV-associated OPSCC, CT offers equivalent diagnostic accuracy to that of combined whole-body PET-CT for clinical staging, and has no appreciable impact on treatment selection. A reduced reliance on routine PET-CT during initial workup of HPV-associated OPSCC may be favorable for otherwise healthy patients with clinically evident sites of primary disease.

Role of PET/CT in the follow-up of postoperative and/or post-therapy cancer rectum: comparison with pelvic MRI

BackgroundIn locally advanced rectal cancer, many imaging modalities are used, for example 18F-2-fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) and MRI. The aim of our study is to compare the diagnostic accuracy of 18 F-FDG-PET/CT & pelvic MRI; as well as to investigate the possible added value of using combined pelvic MRI and PET-CT for assessment of tumor response.ResultsRegarding the presence of local tumor, both PET CT and MRI showed perfect agreement with 97.1% overall accuracy, while in N category, PET CT showed higher specificity but lower sensitivity than MRI. MRI was superior to PET/CT in detecting extension to nearby organs; owing to the more anatomical details of MRI regarding the involvement of mesorectal fascia and EMVI. Almost total agreement of both MRI and PET/CT was noticed in evaluating post-therapy and postoperative complications.ConclusionFor locally advanced rectal cancer (pT3–4 N0 M0 or any T N1 M0), a multimodality strategy has been shown to be the best option to evaluate local disease process, using the diagnostic criteria that were based on morphology, as well as glucose uptake, instead of the SUV alone for reassessment of post-therapy or postoperative changes.

Combined PET-CT and MRI for response evaluation in patients with squamous cell anal carcinoma treated with curative-intent chemoradiotherapy

ObjectivesTo assess the effectiveness of fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) for response assessment post curative-intent chemoradiotherapy (CRT) in anal squamous cell carcinoma (ASCC).MethodsConsecutive ASCC patients treated with curative-intent CRT at a single centre between January 2018 and April 2020 were retrospectively identified. Clinical meta-data including progression-free survival (PFS) and overall survival (OS) outcomes were collated. Three radiologists evaluated PET-CT and MRI using qualitative response assessment criteria and agreed in consensus. Two-proportion z test was used to compare diagnostic performance metrics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy). Kaplan-Meier analysis (Mantel-Cox log-rank) was performed.ResultsMRI (accuracy 76%, PPV 44.8%, NPV 95.7%) and PET-CT (accuracy 69.3%, PPV 36.7%, NPV 91.1%) performance metrics were similar; when combined, there were statistically significant improvements (accuracy 94.7%, PPV 78.9%, NPV 100%). Kaplan-Meier analysis demonstrated significant differences in PFS between responders and non-responders at PET-CT (p = 0.007), MRI (p = 0.005), and consensus evaluation (p < 0.001). Cox regression analysis of PFS demonstrated a lower hazard ratio (HR) and narrower 95% confidence intervals for consensus findings (HR = 0.093, p < 0.001). Seventy-five patients, of which 52 (69.3%) were females, with median follow-up of 17.8 months (range 5–32.6) were included. Fifteen of the 75 (20%) had persistent anorectal and/or nodal disease after CRT. Three patients died, median time to death 6.2 months (range 5–18.3).ConclusionCombined PET-CT and MRI response assessment post-CRT better predicts subsequent outcome than either modality alone. This could have valuable clinical benefits by guiding personalised risk-adapted patient follow-up.Key Points• MRI and PET-CT performance metrics for assessing response following chemoradiotherapy (CRT) in patients with anal squamous cell carcinoma (ASCC) were similar.• Combined MRI and PET-CT treatment response assessment 3 months after CRT in patients with ASCC was demonstrated to be superior to either modality alone.• A combined MRI and PET-CT assessment 3 months after CRT in patients with ASCC has the potential to improve accuracy and guide optimal patient management with a greater ability to predict outcome than either modality alone

IPET-CT in inflammatory diseases of kidneys and bladder: diagnostic efficacy

Introduction. The incorporation of combined positron emission tomography-computed tomography (PET-CT) into clinical practice has significantly expanded the understanding of the pathogenesis of many diseases. Evidence-based data on the diagnostic efficacy in infectious and inflammatory diseases is increasing, making this imaging method very promising. Purpose of the study. To study the diagnostic efficacy of 18F-FDG PET-CT in various chronic inflammatory diseases of kidneys and bladder.Materials and methods. A retrospective study of the results of whole-body 18F-FDG PET-CT in 45 patients was carried out. Patients underwent an investigation at various times after surgical treatment of localized oncology of the anogenital zone at the T1N0M0 stage without the involvement of the genitourinary system. It was found that 24 patients had a history of chronic pyelonephritis and 21 patients had manifestations of radiation cystitis. Repeated PET/CT scans were performed after a course of therapy for inflammatory urological diseases to assess the treatment results of the underlying pathology.Results. The latent course of chronic renal failure was accompanied by a diffuse decrease in 18F-FDG metabolism in the renal parenchyma with its partial recovery after etiotropic therapy and urine sanitation. Hypermetabolism of 18F-FDG was detected in the bladder wall during manifestations of radiation cystitis, which was leveled during therapy and relief of urinary syndrome manifestations. Bacterial and radiation inflammation differed in molecular-cell responses to the pathogen, while the results of urinalysis, indicating the effectiveness of the treatment, coincided with the visual and digital indicators of the restoration of adequate energy metabolism in the studied tissues.Conclusions. Metabolism of 18F-FDG in the kidneys and bladder can objectively reflect the nature of inflammation and complement the data on the effectiveness of the treatment.

Follow-Up 18F-FDG PET/CT versus Contrast-Enhanced CT after Ablation of Liver Metastases of Colorectal Carcinoma-A Cost-Effectiveness Analysis.

Purpose: After a percutaneous ablation of colorectal liver metastases (CRLM), follow-up investigations to evaluate potential tumor recurrence are necessary. The aim of this study was to analyze whether a combined 18F-Fluordesoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) scan is cost-effective compared to a contrast-enhanced computed tomography (CE-CT) scan for detecting local tumor progression. Materials and Methods: A decision model based on Markov simulations that estimated lifetime costs and quality-adjusted life years (QALYs) was developed. Model input parameters were obtained from the recent literature. Deterministic sensitivity analysis of diagnostic parameters based on a Monte-Carlo simulation with 30,000 iterations was performed. The willingness-to-pay (WTP) was set to $100,000/QALY. Results: In the base-case scenario, CE-CT resulted in total costs of $28,625.08 and an efficacy of 0.755 QALYs, whereas 18F-FDG PET/CT resulted in total costs of $29,239.97 with an efficacy of 0.767. Therefore, the corresponding incremental cost-effectiveness ratio (ICER) of 18F-FDG PET/CT was $50,338.96 per QALY indicating cost-effectiveness based on the WTP threshold set above. The results were stable in deterministic and probabilistic sensitivity analyses. Conclusion: Based on our model, 18F-FDG PET/CT can be considered as a cost-effective imaging alternative for follow-up investigations after percutaneous ablation of colorectal liver metastases.

Mediastinoskopi: Küçük Hücreli Dışı Akciğer Kanseri N-Evrelemesinde Hala Geçerli Mi Yoksa Değersiz Bir Yöntem Midir?

This study compares the two most frequently used methods, combined positron emission tomography-computed tomography (PET/CT) and mediastinoscopy, in detecting mediastinal lymph node metastases. It has been investigated whether PET/CT can be used as an alternative method to mediastinoscopy which is considered the gold standard in detecting mediastinal lymph node metastasis. Mediastinal lymph node metastasis is an important factor in treatment and prognosis of non-small cell lung cancer. A total of 102 patients diagnosed with non-small cell lung cancer by our clinic between 2012 and 2017, were enrolled in the study. In total 277 lymph nodes were compared with respect to their histopathologic results and their involvement in positron emission tomography. Specificity value of PET/CT was detected as 84.5% while its negative predictive value, positive predictive value and sensitivity were 82.7%, 69.5% and 66.6%, respectively. In patients who underwent only mediastinoscopy and whose frozen section samples did not demonstrate any metastatic involvement, when histopathological results of lymph node dissection performed by thoracotomy were analyzed, the negative predictive value of mediastinoscopy was calculated as 97%. In total 65 stations including 46 stations smaller than 1 centimeter and 19 stations larger than 1 centimeter, which did not demonstrate any uptake in PET/CT, were sampled. No metastasis was detected in histopathologic staging of these lymph nodes. For patients who do not demonstrate any uptake in mediastinal lymph nodes on PET/CT, invasive lymph node sampling is redundant. However, with the aim of avoiding unnecessary thoracotomies, invasive lymph node sampling is required, even though mediastinal lymph node uptake detected with PET/CT is below the threshold of malignancy.

Effect of cocoa on the brain and gut in healthy subjects: a randomised controlled trial.

Dark chocolate is claimed to have effects on gastrointestinal function and to improve well-being. This randomised controlled study tested the hypothesis that cocoa slows gastric emptying and intestinal transit. Functional brain imaging identified central effects of cocoa on cortical activity. Healthy volunteers (HV) ingested 100 g dark (72 % cocoa) or white (0 % cocoa) chocolate for 5 d, in randomised order. Participants recorded abdominal symptoms and stool consistency by the Bristol Stool Score (BSS). Gastric emptying (GE) and intestinal and colonic transit time were assessed by scintigraphy and marker studies, respectively. Combined positron emission tomography-computed tomography (PET-CT) imaging assessed regional brain activity. A total of sixteen HV (seven females and nine males) completed the studies (mean age 34 (21-58) years, BMI 22·8 (18·5-26·0) kg/m2). Dark chocolate had no effect on upper gastrointestinal function (GE half-time 82 (75-120) v. 83 (60-120) min; P=0·937); however, stool consistency was increased (BSS 3 (3-5) v. 4 (4-6); P=0·011) and there was a trend to slower colonic transit (17 (13-26) v. 21 (15-47) h; P=0·075). PET-CT imaging showed increased [18F]fluorodeoxyglucose (FDG) in the visual cortex, with increased FDG uptake also in somatosensory, motor and pre-frontal cortices (P&lt;0·001). In conclusion, dark chocolate with a high cocoa content has effects on colonic and cerebral function in HV. Future research will assess its effects in patients with functional gastrointestinal diseases with disturbed bowel function and psychological complaints.

Clinical Values of Combined Diffused Optical Tomography and PET-CT in the Diagnosis of Breast Cancer.

Objective To investigate the clinical values of combined diffused optical tomography (DOT) combined positron emission tomography-computed tomography (PET-CT) in the diagnosis of breast cancer. Methods We performed DOT and PET-CT examinations in 38 patients with 40 lesions and compared these images with the pathological results to analyze the sensitivity,specificity,accuracy,positive predictive value,and negative predictive value of these two techniques and their combination.Results The sensitivity,specificity,accuracy,positive predictive value,and negative predictive value in diagnosing breast cancer were 78.26%,76.47%,77.50%,72.22%,and 81.81% for DOT,86.96%,82.35%,85.00%,86.96%,and 82.35% for PET-CT,and 86.96%,94.12%,90.00%,95.23%,and 84.21% for the combination of PET-CT and DOT.Conclusions DOT and PET-CT are both effective diagnostic methods for breast cancer.Combined DOT and PET-CT can improve the diagnostic efficacy in terms of specificity,positive predictive value,and accuracy.

Intensive FDG-PET/CT Uptake Suggestive of Malignancy Misleading the Diagnosis of Sclerosing Pneumocytoma

Introduction: Combined Positron Emission Tomography-Computed Tomography with 18-fluoro-desoxy-glucose (FDG-PET/CT) is highly sensitive in differentiating malignant from benign pulmonary lesions and is part of the current recommended practices for non-invasive lung nodule assessment. However, many solid pulmonary nodules may show misleading miscellaneous features and can be mistakenly diagnosed as malignant lesions. Case Report: Herein we report the case of a passive smoking female patient with multiple comorbidities, who was referred for a solitary pulmonary nodule randomly discovered. Chest imaging showed a middle lobe 16-mm nodule with an intensive uptake (SUVmax 7.6) highly suggestive of malignant origin. The patient underwent middle lobectomy with radical lymphadenectomy because the malignancy was not excluded on frozen section. Definitive pathological examination showed a sclerosing pneumocytoma. Conclusion: FDG-PET/CT is an accurate imaging tool for assessment of solid pulmonary nodules. However, false positive results of some benign lesions have to be kept in mind. Therefore, FDG-PET/CT features have to be interpreted according to the patients background and clinical data, in order to provide the best appropriate management.

The Use of Radiolabelled 18-F-2-Deoxy-2-Fluro-Glucose (18-FDG) in Combined Positron Emission Tomography-Computed Tomography (PET-CT) to Evaluate Infection: Lessons Learned from a Case Series of 23 Patients with Chronic Granulomatous Disease (CGD)

The Use of Radiolabelled 18-F-2-Deoxy-2-Fluro-Glucose (18-FDG) in Combined Positron Emission Tomography-Computed Tomography (PET-CT) to Evaluate Infection: Lessons Learned from a Case Series of 23 Patients with Chronic Granulomatous Disease (CGD)

The Optimality of Different Strategies for Supplemental Staging of Non–Small-Cell Lung Cancer: A Health Economic Decision Analysis

ObjectivesTo assess the expected costs and outcomes of alternative strategies for staging of lung cancer to inform a Danish National Health Service perspective about the most cost-effective strategy. MethodsA decision tree was specified for patients with a confirmed diagnosis of non–small-cell lung cancer. Six strategies were defined from relevant combinations of mediastinoscopy, endoscopic or endobronchial ultrasound with needle aspiration, and combined positron emission tomography-computed tomography with F18-fluorodeoxyglucose. Patients without distant metastases and central or contralateral nodal involvement (N2/N3) were considered to be candidates for surgical resection. Diagnostic accuracies were informed from literature reviews, prevalence and survival from the Danish Lung Cancer Registry, and procedure costs from national average tariffs. All parameters were specified probabilistically to determine the joint decision uncertainty. The cost-effectiveness analysis was based on the net present value of expected costs and life years accrued over a time horizon of 5 years. ResultsAt threshold values of around €30,000 for cost-effectiveness, it was found to be cost-effective to send all patients to positron emission tomography-computed tomography with confirmation of positive findings on nodal involvement by endobronchial ultrasound. This result appeared robust in deterministic sensitivity analysis. The expected value of perfect information was estimated at €52 per patient, indicating that further research might be worthwhile. ConclusionsThe policy recommendation is to make combined positron emission tomography-computed tomography and endobronchial ultrasound available for supplemental staging of patients with non–small-cell lung cancer. The effects of alternative strategies on patients’ quality of life, however, should be examined in future studies.

Myocardial Positron Emission Tomography/Computed Tomography Scan Revealing Right Coronary Artery Involvement in Large Vessel Vasculitis

To the Editor: We describe a 55-year-old woman who presented with epigastric pain radiating to the back, chest discomfort, and fever. Blood tests showed increased level of acute-phase reactants. Computed tomography angiography (CTA) revealed a partially thrombized aneurysm of the superior mesenteric artery and stenosis of the celiac trunk and inferior mesenteric artery. Arteriography confirmed the stenoses. Two angioplasties were successfully performed, leading to prompt resolution of the abdominal pain. She was then treated with acetylsalicylic acid 100 mg/day and clopidogrel 75 mg/day. Nevertheless, her chest pain worsened, she developed a troponin-negative crescendo angina, and was diagnosed with a non-ST-elevation acute coronary syndrome. Cardiac angiography showed normal coronary arteries. Myocardial blood flow was assessed with a combined positron emission tomography-computed tomography (PET/CT) and 13N-ammonia. A stress-rest protocol with dipyridamole was used (Figure 1). Figure 1. Myocardial perfusion PET/CT images … Address correspondence to Dr. M. Piga, Rheumatology Unit, University Clinic AOU, SS 554 – 09 042 Monserrato, Cagliari, Italy. E-mail: matteopiga{at}alice.it

Magnetic resonance imaging and positron emission tomography-computed tomography evaluation of soft tissue sarcoma with surgical and histopathological correlation

Purpose:The aim of this study was to evaluate the role of positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) in characterization and pre-operative staging of soft-tissue sarcoma (STS) and correlating with operative and histopathological findings.Materials and Methods:Twenty patients (age range 16-72 years [mean 44.4 years]) with resectable and STS were included in this prospective study. Pre-operative MRI was carried out in all patients with acquisition of T1W, T2W, and short tau inversion recovery (STIR) sequences in appropriate planes. Contrast enhanced MRI was performed in four patients. Whole body PET-CT was performed in 13 patients. Demographic data, clinical features, pre-operative imaging analysis, operative, and histopathological findings were analyzed using SPSS software version 11.5.Results:The most common histologic type was malignant fibrous histiocytoma (MFH) (30%). Of 18 STSs 20 were high-grade. Agreement existed between MR and operative size. MRI had 100% negative predictive value (NPV) in predicting neurovascular bundle involvement. However, positive predictive value (PPV) was 33%. MRI had PPV of 20% while PET-CT had 50% PPV in detecting lymph node involvement. Overall staging accuracy of MRI was 75% when correlated with surgical and histopathological findings. Combined PET-CT and MRI staging, in 13 patients, was better (92.31%) when compared with staging with MRI (84.62%). Specific diagnosis on image characteristics was correctly suggested in 35% patients.Conclusions:MRI is the robust modality in local staging of STSs and PET-CT adds greater accuracy to overall staging in combination with MRI.

Semiautomatic Algorithm for Lymph Node Analysis Corrected for Partial Volume Effects in Combined Positron Emission Tomography-Computed Tomography

Positron emission tomography-computed tomography (PET-CT) is superior compared to stand-alone PET in evaluation of malignancies. Few studies have employed high-resolution structural information to correct PET. We designed a semiautomatic algorithm using CT and PET to obtain a partial volume corrected (PVC) standardized uptake value (SUV) and a combined morphologic and functional parameter (multimodal SUV) for lymph node assessment. Lesions were segmented by a semiautomatic algorithm in CT images. Lesion volume was used for PVC and for calculating the multimodal SUV. The method was applied to 47 lymph nodes (30 patients) characterized as suspicious in 18F-fluorodeoxyglucose-PET-CT. In phantoms, PVC improved significantly the measured uptake of the lesion. In patients, 36 lymph nodes could be segmented without problems; in 11 lesions, a manual interaction was necessary. SUVs before PVC (mean 1.29) increased significantly (p < .0005) after PVC (mean 2.8). If SUV 2.5 was used as a threshold value to distinguish between benign and malignant lesions, 11 of the 47 lesions changed from benign to malignant after the PVC. The mean multimodal SUV was 0.39 mL for the benign lesions and 4.47 mL for the malignant lesions. In this work we presented a method for quantitative analysis of lymph nodes in PET-CT. PVC leads to significant differences in SUV.

Response assessment by combined PET–CT scan versus CT scan alone using RECIST in patients with locally advanced head and neck cancer treated with chemoradiotherapy

PurposeRECIST have limitations when applied to potentially curable locally advanced squamous cell carcinoma of the head and neck (SCCHN). [18F]fluorodeoxyglucose–positron emission tomography (PET) scan may be useful in assessing treatment response and predicting patient outcome. Patients and methodsWe studied patients with previously untreated stages III–IVb SCCHN treated with primary concurrent chemoradiotherapy on five prospective clinical trials. Response was assessed by clinical exam, computed tomography (CT), and PET portions of combined PET–CT scan ∼8 weeks after completion of chemoradiotherapy. ResultsFifty-three patients were analyzed. Complete response (CR) was demonstrated in 42 patients (79%) by clinical exam, 15 (28%) by CT, and 27 (51%) by PET. CR as assessed by PET, but not as assessed by clinical exam or CT using RECIST, correlated significantly with progression-free status (PFS) (P < 0.0001). The 2-year PFS for patients with CR and without CR by PET was 93% and 48%, respectively (P = 0.0002). ConclusionsA negative PET scan on combined PET–CT after chemoradiotherapy is a powerful predictor of outcome in patients receiving curative chemoradiotherapy for SCCHN. PET–CT is indicated for response evaluation in this setting to improve the accuracy of post-treatment assessment by CT.

Positron emission tomography‐computed tomography adds to the management of salivary gland malignancies

To evaluate the efficacy of combined positron emission tomography-computed tomography (PET-CT) in identifying salivary gland malignancies and to examine the role of PET-CT in the management of these patients. Retrospective chart review. Fifty-five patients with diagnosed salivary gland cancer who had undergone PET-CT scanning were retrospectively reviewed from January 2000 to October 2008. PET-CT scans using intravenous contrast were correlated with clinicopathological information to determine diagnostic accuracy of disease extent. The impact of PET-CT findings on therapeutic management was analyzed. All histopathologic grades were included in the study. Overall, PET-CT demonstrated a sensitivity of 74.4%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 61.5%. PET-CT also identified unrecognized distant metastases in the following sites: six lung, five bone, two distant lymph nodes, and one liver. PET-CT added to management in 26 patients (47.3%), and it was the deciding diagnostic modality in eight patients (14.5%). Of these 26 patients, 14 patients underwent additional surgery. Three patients with recurrence underwent PET-CT scan-directed radiation and/or chemotherapy, whereas nine patients diagnosed with distant disease received palliative treatment. PET-CT is useful for planning the most appropriate treatment by identifying clinically unrecognized disease. PET-CT shows a high diagnostic accuracy for detecting disease recurrence and distant metastases, thus helping to determine whether patients are candidates for potentially curative or palliative treatment.

Clinical Usefulness of Positron Emission Tomography–Computed Tomography in Recurrent Thyroid Carcinoma

To determine the efficacy of combined positron emission tomography-computed tomography (PET-CT) in identifying recurrent thyroid cancer and to elucidate its role in the clinical management of thyroid carcinoma. Retrospective study. Tertiary care referral academic center. One hundred twenty-four patients with previously treated thyroid carcinoma who underwent PET-CT. PET-CT images were correlated with clinicopathologic information. The influence of PET-CT findings on disease status determination and the treatment plan was evaluated. Among 121 patients undergoing iodine I 131 ((131)I) imaging (an (131)I image was unavailable for 3 patients), 80.6% had negative findings on (131)I imaging before undergoing PET-CT. Among 75 patients who had positive findings on PET-CT, 71 were true positive results. Among 49 patients who had negative findings on PET-CT, 32 were true negative results. Therefore, PET-CT demonstrated a sensitivity of 80.7%, specificity of 88.9%, positive predictive value of 94.7%, and negative predictive value of 65.3%. A significant difference was noted in the mean serum thyroglobulin levels between patients with positive vs negative PET-CT findings (192.1 vs 15.0 ng/mL, P = .01) (to convert thyroglobulin level to micrograms per liter, multiply by 1.0). Overall, distant metastases were detected in 20.2% of patients using PET-CT. There was an alteration of the treatment plan in 28.2% of patients as a result of added PET-CT information, and 21.0% of patients underwent additional surgery. PET-CT is usually performed in patients with thyroid cancer having elevated thyroglobulin levels but non-(131)I-avid tumors and has high diagnostic accuracy for identifying local, regional, and distant metastases. Additional information from PET-CT in patients with (131)I-negative and thyroglobulin-positive tumors frequently guides the clinical management of recurrent thyroid carcinoma.

Utilidad de la PET-TC en la estadificación previa a la cirugía por metástasis hepáticas de carcinoma colorrectal

Unsuspected intrahepatic and extrahepatic metastases are frequently discovered at laparotomy in patients with resectable colorectal liver metastases (CLM), and 60% of these patients will develop a recurrent tumour within 3 years, after a "curative" liver resection. These findings strongly support the need for more effective preoperative staging. The combined positron emission tomography-computed tomography technique (PET-CT) has emerged as a promising diagnostic modality for determining whether patients with recurrent disease in the liver are suitable candidates for curative resection. The aim of this study was to assess the additional value of information provided by PET-CT compared to that of conventional radiological studies (CT and MR) in patients with resectable CLM. Between June 2006 and August 2007, 63 patients evaluated for a first resection of CLM were entered into a prospective database. Each patient received a CT-MR and a PET-CT. Forty-three patients underwent a laparotomy and 42 a hepatectomy. The main end point of the study was to assess the impact of the PET-CT findings on the therapeutic strategy. New findings in the PET-CT resulted in a change in the therapeutic strategy in 9 (14%) of the patients. However, PET-CT provided additional information was true positive by revealing abdominal extrahepatic metastases only in 4 (6.4%) patients, and falsely over-staged four patients and under staged one patient. Lesion-by-lesion sensitivity and predictive positive value for liver lesions were 78,4% and 96% for CT-MR alone, and 55% and 100% for PET-CT respectively. PET-CT was superior to CT-MR for the detection of local recurrence at the site of the initial colorectal surgery. In the selection of patients with CLM being considered for surgical therapy, PET-CT provided useful information only in 6.4% of cases. Possibly longer follow-up will increase this percentage. Our findings support the use of PET-CT mainly in patients with high risk of local recurrence.

PET-CT in oncology: making the most of CT

Combined positron emission tomography–computed tomography (PET-CT) has made a significant impact on cancer imaging. The use of CT to map tissue attenuation for correction of PET images and the ability to co-register the functional information provided by PET with the anatomical data afforded by CT, has resulted in demonstrable improvements in diagnostic accuracy. However, attenuation correction and anatomical localisation may not represent the full benefits of integrating CT with PET. The use of CT acquisition techniques for patient positioning and the use of contrast media can improve diagnostic performance, and incorporation of CT image processing techniques such as perfusion CT, 3D imaging and computer-assisted diagnosis offers new applications. The interpretation of PET-CT images can be improved by fully integrating the morphological appearances on CT into image analysis. Better utilisation of the CT component of PET-CT could further enhance the benefits of PET-CT in oncology but will have implications for manufacturers and purchasers of PET-CT equipment and analysis software. Furthermore, specialists working in PET-CT will need CT competencies beyond knowledge of cross-sectional anatomy. CT continues to exhibit rapid evolution and these advances will inevitably impact on the practice of PET-CT.

Normal uptake of 18F-FDG in the testis: an assessment by PET/CT

The aim of this study was to assess the physiological uptake of 18F-fluoro-2-deoxyglucose (FDG) by an apparently normal testis with combined positron emission tomography-computed tomography (PET/CT) and its correlation with age, blood glucose level, and testicular volume. The testicular uptake of 18F-FDG, expressed as the standardized uptake value (SUV), was measured on PET/CT images in 203 men. The correlation between SUV and age, blood glucose level, and testicular volume was assessed. The SUV in the total of 406 testes was 2.44 +/- 0.45 (range 1.23-3.85). The SUV was 2.81 +/- 0.43 (2.28-3.85) for 30-39 years (n = 12), 2.63 +/- 0.45 (1.77-3.75) for 40-49 years (n = 64), 2.46 +/- 0.35 (1.44-3.15) for 50-59 years (n = 82), 2.51 +/- 0.41 (1.50-3.46) for 60-69 years (n = 86), 2.43 +/- 0.47 (1.42-3.29) for 70-79 years (n = 86), and 2.18 +/- 0.45 (1.23-3.03) for 80-89 years (n = 76). When we calculated the mean SUV of bilateral testes in each patient, there were significant statistical differences between those in the age group of 30-39 years and 80-89 years, 40-49 years and 80-89 years, and 50-60 years and 80-89 years, when using an unpaired test with Bonferroni correction. The laterality index (|L - R|/(L + R) x 2) in 203 men was 0.066 +/- 0.067 (0-0.522). There was a mild correlation between the mean SUV and age (r = -0.284, P < 0.001) as well as between the mean SUV and mean volume (r = +0.368, P < 0.001). There was no correlation between the mean SUV and glucose blood level (r = -0.065, P = 0.358). Some uptake of FDG is observed in the normal testis and declines slightly with age. Physiological FDG uptake in the testis should not be confused with pathological accumulation.