Feasibility and performance of an adaptive contrast-oriented FDG PET/CT quantification technique for global disease assessment of malignant pleural mesothelioma and a brief review of the literature.

OBJECTIVE: Treatment of malignant pleural mesothelioma (MPM) remains very challenging. Assessment of response to treatment is necessary for modifying treatment and using new drugs. Global disease assessment (GDA) by implementing image processing methods to extract more information out of positron emission tomography (PET) images may provide reliable information. In this study we show the feasibility of this method of semi-quantification in patients with mesothelioma, and compare it with the conventional methods. We also present a review of the literature about this topic. METHODS: Nineteen subjects with histologically proven MPM who had undergone fluoride-18-fluorodeoxyglucose PET/computed tomography ((18)F-FDG PET/CT) before and after treatment were included in this study. An adaptive contrast-oriented thresholding algorithm was used for the image analysis and semi-quantification. Metabolic tumor volume (MTV), maximum and mean standardized uptake volume (SUVmax, SUVmean) and total lesion glycolysis (TLG) were calculated for each region of interest. The global tumor glycolysis (GTG) was obtained by summing up all TLG. Treatment response was assessed by the European Organisation for Research and Treatment of Cancer (EORTC) criteria and the changes of GTG. Agreement between global disease assessment and conventional method was also determined. RESULTS: In patients with progressive disease based on EORTC criteria, GTG showed an increase of 150.7 but in patients with stable or partial response, GTG showed a decrease of 433.1. The SUVmax of patients before treatment was 5.95 (SD: 2.93) and after the treatment it increased to 6.38 (SD: 3.19). Overall concordance of conventional method with GDA method was 57%. Concordance of progression of disease based on conventional method was 44%, stable disease was 85% and partial response was 33%. Discordance was 55%, 14% and 66%. CONCLUSIONS: Adaptive contrast-oriented thresholding algorithm is a promising method to quantify the whole tumor glycolysis in patients with mesothelioma. We are able to assess the total metabolic lesion volume, lesion glycolysis, SUVmax, tumor SUVmean and GTG for this particular tumor. Also we were able to demonstrate the potential use of this technique in the monitoring of treatment response. More studies comparing this technique with conventional and other global disease assessment methods are needed in order to clarify its role in the assessment of treatment response and prognosis of these patients.

Role of 18F-FDG-PET/CT in the management of marginal zone B cell lymphoma.

The use of PET in patients with marginal zone B cell lymphoma (MZL) is controversial because of variability of fluorodeoxyglucose (FDG) avidity. We analyzed 40 PET/CT in 25 consecutive patients to compare its performance with CT at staging and as a first-line response assessment. Sensitivity of PET/CT and CT was 96 and 76%. Mean standard uptake value was 6.1, 6.9 and 3.4 (p = 0.3) in nodal, extranodal and splenic subtypes, respectively. Of 17 patients (extranodal: n = 9; nodal: n = 6; splenic subtype: n = 2) with both imaging tests available at diagnosis, 8 (47%) had more involved areas with PET/CT than with CT, 75% of which were extranodal lesions. PET/CT resulted in upstaging of five patients although treatment of only two of them was changed. Responses of 15 patients with post-treatment PET/CT were the following: 9 negative and 6 positive of which 3 were isolated residual lesions. Progression was documented in two of these three patients. Response was also assessed by CT in 11 patients. Discrepancies were found in three: Two were in complete remission by CT while PET/CT detected localized residual disease; another patient was in partial remission by CT, whereas PET/CT showed only one positive lesion. Two of these three patients relapsed. Patients with negative post-treatment PET/CT did not relapse. With a median follow-up of 50 months (10-152 months), 3-year overall survival was 100 and 80% for patients with negative and positive post-treatment PET/CT (p = 0.2). Three-year disease-free survival was 86%; the negative predictive value (NPV) was 100%, and the positive predictive value (PPV) was 83.3%. Although a larger number of patients will be required to further confirm these data, we can conclude that PET/CT is a useful imaging tool for both staging and response assessment in patients with nodal and extranodal MZL as a result of its high sensitivity, NPV and PPV.

Role of 18F-FDG-PET/CT in the management of Burkitt lymphoma.

UNLABELLED: Burkitt lymphoma (BL) is highly FDG-avid even though its usefulness in the management of these patients is still controversial. AIM: We analyzed the role of positron emission tomography/computerized tomography (PET/CT) in staging newly diagnosed patients with BL and evaluating disease after first-line chemotherapy. METHODS: Fifty-two PET/CTs were performed in 32 patients (20 at diagnosis, 27 after treatment, five to monitor residual disease). Involved areas were retrospectively compared with those observed in contrast-enhanced CT. RESULTS: Discrepancies were found in 64.7% of patients for whom results of both tests at diagnosis were available (n = 17), most of them involving extranodal sites. Regarding response assessment, discrepancies were observed in 38% of patients with both tests (5/13): residual masses detected by CT with negative PET/CT. Of 27 patients with post-treatment PET/CT, 22 were in complete remission whereas one true-positive and four false-positive lesions (two nodal and two extranodal) were detected. With a median follow-up of 27 months, 22 patients with negative PET/CT did not relapse. Thus, negative predictive value (NPV) was 100%. With respect to positive predictive value (PPV), one of five patients with positive assays after treatment died due to progression while the remaining four had false-positive lesions. Nevertheless, for these four patients, mean SUVmax at nodal sites was 4.1 vs. 14.9 at diagnosis, while mean SUVmax at extranodal sites was 3.8 vs. 12.1. Thus, with a cutoff value for SUVmax < 66% of that observed at diagnosis, PPV was also 100%. CONCLUSION: More accurate staging can be achieved using PET/CT. NPV reaches 100%, and using a ΔSUV < 66%, a high PPV is also observed.

[SPECT/CT with 99mTc-HMPAO in progressive encephalitis mediated by anti-GAD antibodies]. / SPECT/TC con 99mTc-HMPAO en la encefalitis progresiva mediada por anticuerpos anti-GAD.

TITLE: SPECT/TC con 99mTc-HMPAO en la encefalitis progresiva mediada por anticuerpos anti-GAD.

Quantitative assessment of global hepatic glycolysis in patients with cirrhosis and normal controls using 18F-FDG-PET/CT: a pilot study.

OBJECTIVE: To compare differences in global measures of hepatic metabolism between control subjects and subjects with cirrhosis. MATERIALS AND METHODS: FDG-PET/CT scans of 33 subjects either without or with cirrhosis were analyzed retrospectively and classified as follows: group 1 includes subjects without cirrhosis or extrahepatic malignancy (1a) (n=11) and subjects without cirrhosis but with history of extrahepatic malignancy (1b) (n=10); group 2 includes subjects with cirrhosis and history of extrahepatic malignancy (n=12). Subjects with focal hepatic lesions, prior hepatic surgery, co-existing liver pathology, or who received chemotherapy or radiation therapy within the last 6 months were excluded. The hepatic volumes, hepatic mean standardized uptake value (SUVmean), and global hepatic glycolysis (GHG) were compared between groups. RESULTS: Subjects with cirrhosis showed a lower average hepatic SUVmean as compared to non-cirrhotic patients (1.55±0.29 for group 2 versus 1.81±0.23 for group 1; p value=0.009) and lower average values for GHG (2238.29±903.60 for group 2 versus 2974.67±829.16 for group 1; p value=0.024). No differences were noted between the non-cirrhotic subgroups (i.e., between the groups 1a and 1b) without and with associated extrahepatic malignancy, respectively. CONCLUSIONS: We hypothesize that presence of fibrosis, reduction of active inflammation, and decreased hepatic metabolism and function are potential causes of the lower FDG uptake in cirrhotic livers. Our results also indicate that extrahepatic cancer status does not influence FDG uptake in the non-cirrhotic liver in subjects without hepatic metastases.

Clinical features and 123I-FP-CIT SPECT imaging in vascular parkinsonism and Parkinson's disease.

OBJECTIVES: To analyse the differences in the clinical features and characteristics of (123)I-labelled 2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl) nortropane ((123)I-FP-CIT) single photon emission CT (SPECT) imaging among patients with vascular parkinsonism (VP) and Parkinson's disease (PD). METHODS: We performed a case-control study to compare clinical features and qualitative and semi-quantitative analyses of (123)I-FP-CIT SPECT images between 106 patients with VP and 280 patients with PD. A case series study was used to search for clinical features related to SPECT or neuroimaging findings among patients with VP. RESULTS: Patients with VP had a higher age at symptom onset and lower disease duration than patients with PD. The most frequent symptom at onset was gait disorder in VP and tremor in PD. Gait disorder, postural instability and falls were more frequent in VP. Rest and mixed tremor were more prevalent in PD. Of the patients who received levodopa treatment in the VP group, only about half had a good response. Qualitatively (123)I-FP-CIT SPECT images were normal in 32.5% of patients with VP and abnormal in all patients with PD. The use of different visual score patterns showed higher ability to differentiate VP from PD. Semi-quantitative analysis showed significantly higher uptake in the striatum, caudate and putamen in VP. The asymmetry index was higher in patients with PD. Among patients with VP, falls were the only clinical feature that demonstrated a correlation with the SPECT visual pattern. CONCLUSION: Our data contribute to the confirmation that VP and PD are two different clinical entities. Neurological signs, response to treatment and qualitative and semi-quantitative (123)I-FP-CIT SPECT analyses may help to make the diagnosis.