Comparison of 18F-FDG Pet/CT and CT: diagnosis performance in lymphoma patient after treatment.

OBJECTIVE: Retrospectively comparing 18F-FDG PET/CT and CT findings at the same anatomic locations in patients with lymphoma by using a combined PET/CT scanner and to analyze the lesions on both metabolic and anatomic bases to evaluate their sensitivity specificity positive predictive value (PPV), negative predictive value (NPV), and accuracy. We analyzed all studies, all patients, common cell type in this study such as diffuse large B cell lymphoma (DLBCL) and Hodgkin's lymphoma and indication of the study such as restaging for recurrence post-therapy and evaluate residual disease within two months after chemotherapy. MATERIAL AND METHOD: Sixty-seven lymphoma patients were studied PET/CT between January 2007 and December 2012 in Siriraj Hospital. We excluded six patients due to no medial report in our hospital. Sixty-one patients (29 male, 32 female, mean age 46.6 +/- 17.7 years, range 8-75) with NHL and with HL) were analyzed for the result of dual-modality PET/CT They underwent 77 18F-FDG PET/CT studies for restaging, for recurrence post-therapy based on 41 studies and evaluation of residual disease within two months after chemotherapy in 36 studies. RESULTS: The statistical parameters of 18F-FDG PET/CT imaging of lymphoma patients after treatment show significantly better specificity than CT and insignificant high accuracy for all studies, all patients, histology of DLBCL, indication of evaluation of active lymphoma within two months after chemotherapy. The 18F-FDG PET/CT parameters of accuracy and PPV are higher than CT without statistical significance. The 18F-FDG PET/CT is not significantly better than CT for histology of Hodgkin's lymphoma and indication of restaging for recurrence post-therapy Nevertheless, the 18F-FDG PET/CT shows slightly improved specificity PPV and accuracy than CT The sensitivity of CT in this study is high and may be from most of our cases selected post-treatment lymphoma that had a residual mass after treatment. Therefore, the sensitivity of PET scan is not significantly higher when compared with CT scan. CONCLUSION: The PET/CT is better than CT for post-treatment lymphoma patient particularly for cell type of DLBCL and indication for evaluation of active lymphoma within two months after chemotherapy.

Cost-effectiveness analysis of 18F-FDG PET/CT in detecting suspected recurrence or metastasis in well-differentiated thyroid carcinoma patients with negative diagnostic total body scan in Thailand: a decision analysis.

OBJECTIVE: To evaluate cost-effectiveness analysis of 18F-FDG PET/CT to detect tumor recurrence or metastasis in well-differentiated thyroid cancer patients with high Tg but negative TBS in Thailand. MATERIAL AND METHOD: A retrospective literature review of 55 studies published between 1978 and 2010 was done. Decision analysis by TreeAge program showed an evaluation of the most cost-effective treatment and 18F-FDG PET/CT scan in thyroid cancer patients with high Tg but negative TBS. The incremental cost and life years gained associated with seven strategies approached were analyzed by the decision tree model. The first strategy was treatment with empirical high dose 131I therapy. The second to the seventh strategies were using imaging investigations by CT scan of neck and chest, 99mTc MIBI scan, and 18F-FDG PET/CT scan to identify recurrent, persistent, and metastatic lesions before the specific treatment via curative surgery, external radiotherapy, and high dose 131I therapy. All strategies were adopted using hospital perspective and direct medical cost was estimated based on the reference price of Siriraj Hospital. Deterministic sensitivity analysis was conducted to investigate the effect of the cost of PET/CT scan. RESULTS: The strategy using 18F-FDG PET/CT scan to detect recurrence or metastasis and possible curative surgery in operable cases and high dose 131I therapy in inoperable cases gave the highest life years gained of 27.08 with cost of 90,227.61 Baht (2,926.24 US dollars) and acceptable incremental cost effectiveness ratio (ICER) of 6,936.88 Baht (224.98 US dollars) per life year gained when compared to the least costly strategy using 99mTc MIBI scan and additional 18F-FDG PET/CT scan in negative MIBI result. Other strategies were dominated by this PET/CT strategy. Deterministic sensitivity analysis (based on the willingness to pay (WTP) 360,000 Baht (11,675.42 US dollars) showed that the cost of PET/CT scan has no impact on the net health benefit. CONCLUSION: Based on the hospital perspective, the cost-effectiveness of 18F-FDG PET/CT scan in detecting suspected recurrence or metastasis in thyroid carcinoma patients with negative diagnostic TBS but high Tg was first done using 18F-FDG PET/CT scan to identify disease, followed by curative surgery or high dose 131I therapy. Moreover cost of PET/CT scan did not influence the net health benefit. This PET/CT benefit is helpfulfor considering the proper PET/CT use for thyroid cancer in Thailand.

Detection of recurrent colorectal cancer by 18F-FDG PET/CT comparison with contrast enhanced CT scan.

OBJECTIVE: To evaluate diagnostic performance of 18F-FDG PET/CT in assessment of recurrence colorectal cancer after treatment in Siriraj Hospital. MATERIAL AND METHOD: The authors retrospectively studied 48 treated colorectal cancer patients with suspected recurrence who underwent 18F-FDG PET/CT and contrast-enhanced CT (CECT). Clinical information, image follow-up for at least one year, and pathological reports of the patients were reviewed for gold standard RESULTS: Recurrent or metastatic disease was found in 36 of 48 patients. Calculated sensitivity, specificity and accuracy of 18F-FDG PET/CT were 94.4%, 66.7%, and 87.5%. 18F-FDG PET/CT can reduce false positive results of CECT in six patients, thus specificity of 18F-FDG PET/CT was statistically significantly better than that of CECT. Using lesion-based analysis with 65 recurrent sites and 26 non-recurrent lesion, 18F-FDG PET/CT showed better sensitivity 87.7%, specificity 61.5%, and accuracy 80.2 than CECT without statistical significance. CONCLUSION: 18F-FDG PET/CT overall showed higher sensitivity, specificity, and accuracy than CECT.

A comparison of the diagnostic performance of half-time SPECT and multiplanar pelvic bone scan in patients with significant bladder artifacts.

OBJECTIVES: The objective of this study was to evaluate the diagnostic performance of half-time single-photon emission computed tomography (SPECT) in the interpretation of bone scans in patients with bladder artifacts in comparison with multiplanar imaging. We also investigated whether SPECT could reduce the radiation dose to nuclear medicine personnel and shorten the acquisition time. MATERIALS AND METHODS: Data from 29 patients with significant bladder artifacts were assessed by two nuclear medicine physicians. The presence or absence of pelvic bone lesions was individually interpreted with both techniques, multiplanar imaging and half-time SPECT, using a three-point pelvic score as follows: 0=definitely no lesion, 1=indeterminate, 2=definite positive lesion. A comparison of the diagnostic performances between the two techniques was made. The radiation dose to personnel and acquisition time were also investigated. RESULTS: Using half-time SPECT, the incidence of studies interpreted without interference from bladder artifacts (artifact-free image) was 100% on both patient-based and lesion-based analyses of 29 patients, whereas multiplanar imaging revealed incidences of 52 and 90% on patient-based and lesion-based analyses, respectively. Ninety percent of technologists and 58% of assistants received 1 µSv/case radiation dose while performing multiplanar imaging. Only 10% of technologists received 1 µSv/case and none of the assistants received a detectable radiation dose from SPECT. The SPECT technique could also reduce the examination time, particularly when positioning time was included. CONCLUSION: Half-time SPECT can significantly improve the diagnostic confidence of interpreting equivocal pelvic lesions in patients with bladder artifacts, compared with multiplanar imaging. This technique also provides lower radiation dose to nuclear medicine staff and requires shorter examination time.