Comparison of PET, CT, and dual-modality PET/CT imaging for monitoring of imatinib (STI571) therapy in patients with gastrointestinal stromal tumors.

This study was implemented to compare the value of PET, CT, and dual-modality PET/CT imaging for assessing gastrointestinal stromal tumor (GIST) response to imatinib therapy. METHODS: Twenty patients with histologically proven GIST underwent (18)F-FDG PET/CT imaging before and 1, 3, and 6 mo after the start of imatinib therapy. Separate PET and CT datasets, side-by-side PET and CT datasets, and fused PET/CT images were evaluated according to World Health Organization, Response Evaluation Criteria in Solid Tumors, and European Organisation for Research and Treatment of Cancer criteria for therapy response. Hounsfield units (HU) were assessed on CT images. A mean follow-up period of 381 +/- 134 d served as the standard of reference. RESULTS: The numbers of lesions detected in all patients were 135 with PET, 249 with CT, 279 on side-by-side evaluation, and 282 on fused PET/CT images. Tumor response was correctly characterized in 95% of patients after 1 mo and 100% after 3 and 6 mo with PET/CT. PET and CT images viewed side by side were correct in 90% of patients at 1 mo and 100% at 3 and 6 mo. PET accurately diagnosed tumor response in 85% of patients at 1 mo and 100% at 3 and 6 mo. CT was found to be accurate in 44% of patients at 1 mo, 60% at 3 mo, and 57% at 6 mo. HU were found to decrease by at least 25% in 12 of 14 responders after 1 mo. CONCLUSION: Tumor response to imatinib should be assessed with a combination of morphologic and functional imaging. Image fusion with combined PET/CT can provide additional information in individual cases when compared with side-by-side PET and CT.     

18F-FDG PET for evaluation of the treatment response in patients with gastrointestinal tract lymphomas.

(18)F-FDG PET is highly sensitive and specific for evaluation of the treatment response of nodal and extranodal diseases in patients with malignant lymphomas. However, no data are available in the literature with regard to (18)F-FDG PET for evaluation of the treatment response in patients with lymphomas with gastrointestinal tract (GIT) involvement. This study was undertaken to investigate the usefulness of (18)F-FDG PET in monitoring the response to the treatment of lymphomas in this setting. METHODS: We retrospectively analyzed 19 patients with different types of lymphomas (10 diffuse large B-cell lymphomas, 4 follicular lymphomas, 3 mantle cell lymphomas, and 2 Hodgkin's disease) involving GIT. Among 19 patients, 4 had gastric involvement, 13 had small bowel involvement, and 2 had small bowel plus colon involvement by lymphomas. All patients underwent (18)F-FDG PET before and after the completion of therapy. The results of (18)F-FDG PET were compared with the results of CT and clinical outcome; the presence of relapse was determined on the basis of positive biopsy results or clinical follow-up data. RESULTS: Of the 19 posttreatment PET scans, 13 showed no pathologic (18)F-FDG uptake, whereas 6 showed persistent (18)F-FDG uptake. Among the 13 patients who had negative PET scans, only 1 patient (7.7%) relapsed, whereas all 6 patients (100%) who had persistent abnormal (18)F-FDG uptake on posttherapy PET scans relapsed. Posttreatment CT scans were negative for 10 patients but showed persistent disease in the remaining 9 patients. Among the 10 patients who had negative CT scans, 9 remained in remission and 1 (10%) relapsed. Of the 9 patients who showed persistent disease, 6 (67%) relapsed and 3 (33%) remained in remission after the mean follow-up of 20 mo. The sensitivity, specificity, positive and negative predictive values, and accuracy of posttherapy (18)F-FDG PET were 86%, 100%, 100%, 92%, and 95%, respectively. The corresponding values for CT were 67%, 75%, 75%, 90%, and 79%, respectively. Patients with positive (18)F-FDG PET results had statistically significantly lower disease-free survival (DFS) (0%) than did those with positive CT results (33%) (P = 0.04). There was no statistically significant difference in DFS between patients with negative (18)F-FDG PET results and patients with negative CT results. CONCLUSION: A positive (18)F-FDG PET scan after the completion of chemotherapy in patients with lymphomas with GIT involvement is a strong predictor of relapse. (18)F-FDG PET has higher diagnostic accuracy than CT in the detection of residual disease after therapy. Despite the mild physiologic (18)F-FDG uptake in the GIT, (18)F-FDG PET has potential value in monitoring the response to treatment in patients with GIT lymphomas, particularly when pretreatment PET results are positive.     

Whole-body (18)F-FDG PET identifies high-risk myeloma.

The purpose of this study was to evaluate the clinical utility of whole-body PET with (18)F-FDG in patients with multiple myeloma and related monoclonal diseases. METHODS: Between July 1, 1996, and July 2000, 98 (18)F-FDG PET scans were obtained for 66 patients, with 25 patients having 2 or more scans. The results were compared with routine clinical and staging information, including CT and MRI scans, as indicated. Of the 66 patients, 16 had previously untreated active myeloma, 14 had monoclonal gammopathy of undetermined significance (MGUS), 10 had disease in remission, and 26 had relapsing disease. RESULTS: Negative whole-body (18)F-FDG PET findings reliably predicted stable MGUS. Of the 14 MGUS patients with follow-up of 3-43+ mo, myeloma has developed in only 1 (7%), at 8 mo. Conversely, the 16 previously untreated patients with active myeloma all had focal or diffusely positive scan findings. Four (25%) of 16 previously untreated patients with positive (18)F-FDG PET findings had negative full radiologic surveys. Another 4 (25%) of 16 patients had focal extramedullary disease. This was confirmed by biopsy or other imaging techniques. Extramedullary uptake also occurred in 6 (23%) of 26 patients with relapse. This extramedullary uptake was a very poor prognostic factor both before treatment and at relapse. For example, median survival was 7 mo for patients with disease relapse. Persistent positive (18)F-FDG PET findings after induction therapy predicted early relapse. In 13 (81%) of 16 patients with relapsing disease, new sites of disease were identified. The (18)F-FDG PET results were especially helpful in identifying focal recurrent disease in patients with nonsecretory or hyposecretory disease amenable to local irradiation therapy, which was used in 6 patients. CONCLUSION: Whole-body (18)F-FDG PET provides important prognostic information, which is clinically useful and complementary to conventional methods of evaluating plasma cell disorders. (18)F-FDG PET is a unique tool for evaluation of nonsecretory myeloma. Residual or recurrent disease after therapy, especially extramedullary disease, is a poor prognostic factor.     

Imatinib mesylate for the treatment of gastrointestinal stromal tumours: best monitored with FDG PET

BACKGROUND: The new anti-cancer drug imatinib mesylate inhibits the tyrosine kinase growth factor receptor, c-KIT, and has shown spectacular activity in patients with gastrointestinal stromal tumours (GISTs). OBJECTIVE: To assess whether fluorodeoxyglucose positron emission tomography (FDG PET) is suitable for response evaluation of this new type of tumour treatment. METHODS: Sixteen consecutive patients with irresectable or metastasized GIST or another c-KIT (CD117) positive mesenchymal tumour underwent FDG PET before and 1 week after the start of treatment with imatinib mesylate (Glivec). Visual findings and standard uptake values (SUVs) were compared with the overall response to treatment, based on clinical and radiological response. RESULTS: PET visualized all known and some unknown tumour locations. The separation by PET after 1 week of treatment in "PET responders" (11/16 patients, mean SUV reduction 65%) versus "PET non-responders" (5/16 patients, mean SUV increase 16%) appeared to match almost perfectly with overall treatment response and proved correct in 14/15 patients (prediction sensitivity 93%). FDG uptake changes after 1 week of treatment were of greater magnitude than tumour volume changes on computed tomography at 8 weeks. Progression-free survival was significantly better in patients with a PET response (P=0.002). PET response predicted treatment outcome better than the radiological response. Finally, PET was helpful during follow-up, in discriminating side effects from tumour progression. CONCLUSION: FDG PET is a valuable tool in patients with gastrointestinal stromal tumours treated with imatinib mesylate. It improves staging, accurately separates responders from non-responders in an early phase, and is helpful during follow-up.     

The Feasibility of 18F-FDG PET scans 1 month after completing radiotherapy of squamous cell carcinoma of the head and neck.

Our purpose was to prospectively evaluate the efficacy of PET with (18)F-FDG 1 mo after the completion of radiotherapy in patients with squamous cell carcinoma of the head and neck (SCCHN). METHODS: Ninety-seven patients underwent (18)F-FDG PET scans before and after radiotherapy for nondisseminated SCCHN. The first scans were obtained no more than 4 wk before the start of radiotherapy, and follow-up scans were obtained 1 mo after the completion of radiotherapy. (18)F-FDG PET images were analyzed using standardized uptake values (SUVs). All patients were followed for at least 6 mo or until death. RESULTS: The median SUVs of preradiotherapy primary sites and nodes were 6.5 (range, 2.3-23.0) and 5.6 (range, 1.2-16.8), respectively. The median SUVs of postradiotherapy primary sites and nodes were 1.8 (range, basal status value to 9.7) and 1.8 (range, basal status value to 8.6), respectively. Evaluation of the postradiotherapy status of tumors in these SCCHN patients showed the sensitivity of (18)F-FDG PET to be 88%, the specificity to be 95%, and the overall diagnostic accuracy to be 94.9%. CONCLUSION: Our results indicate that (18)F-FDG PET might be a valuable imaging method for evaluating the response to radiotherapy in patients with SCCHN. One month after the completion of radiotherapy is not too early for follow-up (18)F-FDG PET to be performed to evaluate the response to radiotherapy.     

<Superscript>18</Superscript>F-fluorodeoxyglucose positron emission tomography in uterine carcinosarcoma

Purpose Uterine carcinosarcomas clinically confined to the uterus usually harbor occult metastases. We conducted a pilot study to evaluate the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in uterine carcinosarcoma. Methods Patients with histologically confirmed uterine carcinosarcoma were enrolled. Abdominal and pelvic magnetic resonance imaging (MRI)/whole-body computed tomography (CT) scan, and whole-body ¹⁸F-FDG PET or PET/CT were undertaken for primary staging, evaluating response, and restaging/post-therapy surveillance. The clinical impact of ¹⁸F-FDG PET was determined on a scan basis. Results A total of 19 patients were recruited and 31 ¹⁸F-FDG PET scans (including 8 scans performed on a PET/CT scanner) were performed. Positive impacts of scans were found in 36.8% (7/19) for primary staging, 66.7% (2/3) for monitoring response, and 11.1% (1/9) for restaging/post-therapy surveillance. PET excluded falsely inoperable disease defined by MRI in two patients. Aggressive treatment applying to three patients with PET-defined resectable stage IVB disease seemed futile. Two patients died of disease shortly after salvage therapy restaged by PET. With PET monitoring, one stage IVB patient treated by targeted therapy only was alive with good performance. Using PET did not lead to improvement of overall survival of this series compared with the historical control (n = 35) (P = 0.779). Conclusions The preliminary results suggest that ¹⁸F-FDG PET is beneficial in excluding falsely inoperable disease for curative therapy and in making a decision on palliation for better quality of life instead of aggressive treatment under the guidance of PET. PET seems to have limited value in post-therapy surveillance or restaging after failure.     

Comparison between 18F-FDG PET, in-line PET/CT, and software fusion for restaging of recurrent colorectal cancer.

The aim of this study was to compare PET with (18)F-FDG PET, in-line PET/CT, and software fusion of independently acquired CT and PET scans for staging of recurrent colorectal cancer (CRC). METHODS: Fifty-one patients with suspected recurrent CRC were studied with in-line PET/CT. Thirty-four of these patients underwent an additional CT scan of the chest or abdomen within 4 wk of PET/CT. Software fusion of PET and CT was performed using a fully automated, intensity-based algorithm. The accuracy of the coregistration of PET and CT scans was evaluated by measuring the distance between landmarks visible in the PET and CT images. Histologic evaluation and follow-up for 6 mo served as the gold standard for the presence or absence of recurrent CRC. RESULTS: On a patient basis, the accuracy of staging was significantly higher for in-line PET/CT than for PET (88% vs. 71%, P = 0.01). Software fusion of the independently acquired PET and CT images was unsuccessful in 8 patients (24%). In the remaining patients, the mean distance between 62 landmarks visible in PET and CT was 12.9 +/- 7.9 mm, whereas it was only 7.7 +/- 4.7 mm for in-line PET/CT (P < 0.001). CONCLUSION: In patients with suspected recurrent CRC, in-line PET/CT significantly improves staging compared with PET alone. Due to its high failure rate, software fusion of independently acquired PET and CT studies cannot be considered to represent an alternative to in-line PET/CT.     

The impact of 18F-FDG PET/CT on assessment of nasopharyngeal carcinoma at diagnosis

The aim of this study was to determine whether the use of whole-body (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) positron emission tomography (PET)/CT alters staging and management of nasopharyngeal carcinoma (NPC) when compared with current staging practice. 52 patients with Stage III-IV NPC without distant metastases on chest X-ray/CT, abdominal ultrasound or bone scan were recruited for the study. Whole-body (18)F-FDG PET/CT and MRI of the head and neck were performed. The scans were compared for extent of the primary tumour (PT), cervical nodal metastases (CNM) and distant metastases (DM). Any discordance in results was assessed with respect to staging and impact on management. MRI and (18)F-FDG PET/CT scans were discordant in 28 (54%) patients. There was discordance in the extent of PT at 28 sites; in all sites, MRI showed more extensive tumour involving the nasopharynx (n = 8), skull base (n = 14), brain (n = 4) and orbit (n = 2). There was also variation among the extent of CNM in four nodes of the retropharyngeal region, with the nodes being positive on MRI. (18)F-FDG PET /CT did not identify any additional distant metastases but did identify a second primary tumour in the colon. The additional use of (18)F-FDG PET/CT did not "up-stage" the overall stage or change management in any patient. In conclusion, there is discordance between MRI and (18)F-FDG PET/CT, and the additional use of (18)F-FDG PET/CT for the current assessment of NPC at diagnosis does not appear to be justified in this cohort of patients.     

Complementary roles of 18F-DOPA PET/CT and 18F-FDG PET/CT in medullary thyroid cancer

Serum calcitonin and carcinoembryonic antigen (CEA) are markers of recurrent or persistent disease in medullary thyroid cancer (MTC). However, conventional imaging often fails to localize metastatic disease. Our aim was to compare fluorine-labeled dihydroxyphenylalanine ((18)F-DOPA) and (18)F-FDG PET/CT with multidetector CT (MDCT) and MRI in recurrent or persistent MTC. METHODS: Nineteen MTC patients with increased calcitonin or CEA on follow-up (mean ± SD, 93 ± 91 mo; range, 4-300 mo) after primary therapy were prospectively imaged with 4 techniques: (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI. Images were analyzed for pathologic lesions, which were surgically removed when possible. The correlation between the detection rate for each method and the calcitonin and CEA concentrations and histopathologic findings was investigated. Results: On the basis of histology and follow-up, one or more imaging methods accurately localized metastatic disease in 12 (63%) of 19 patients. The corresponding figures for (18)F-DOPA PET/CT, (18)F-FDG PET/CT, MDCT, and MRI were 11 (58%) of 19, 10 (53%) of 19, 9 (47%) of 19, and 10 (59%) of 17, respectively. Calcitonin and CEA correlated with (18)F-DOPA PET/CT (P = 0.0007 and P = 0.0263, respectively) and (18)F-FDG PET/CT findings (both P < 0.0001). In patients with an unstable calcitonin doubling time (n = 8), (18)F-DOPA and (18)F-FDG PET/CT were equally sensitive. In contrast, for patients with an unstable CEA doubling time (n = 4), (18)F-FDG PET/CT was more accurate. CONCLUSION: For most MTC patients with occult disease, (18)F-DOPA PET/CT accurately detects metastases. In patients with an unstable calcitonin level, (18)F-DOPA PET/CT and (18)F-FDG PET/CT are complementary. For patients with an unstable CEA doubling time, (18)F-FDG PET/CT may be more feasible. MRI is sensitive but has the highest rate of false-positive results.     

Peritoneal carcinomatosis: role of (18)F-FDG PET.

Peritoneal carcinomatosis can be difficult to diagnose, as CT is insensitive, with peritoneal biopsy and lavage often subject to problems of sampling error. The aim of our study was to evaluate the role of (18)F-FDG PET in detecting peritoneal carcinomatosis in patients with stomach, ovarian, and adrenal cancer and mesothelioma and to compare the results with CT scans in the same patient group. Our secondary aim was to identify characteristic patterns of abdominal (18)F-FDG uptake in biopsy-proven peritoneal disease and to correlate these patterns with available histologic and anatomic findings after surgery and structural imaging. METHODS: The medical records of 88 patients with stomach (n = 48), ovarian (n = 13), and adrenal cancer (n = 6) and mesothelioma (n = 21) were reviewed for the presence of peritoneal tumor on (18)F-FDG PET and CT scans. The results were correlated with either contemporaneous peritoneal biopsy or ascitic aspirate or with radiographic or clinical follow-up if histology was negative or unavailable. Of 24 patients with suspected peritoneal tumor, 17 had biopsy-proven findings of peritoneal disease. RESULTS: Of the 24 patients with suspected peritoneal tumor, (18)F-FDG PET was positive in 14 patients, with 1 of these scans being false-positive, CT was positive in 10 patients, and either PET or CT was positive in 18 patients. This yielded sensitivities of 57% (13/23), 42% (10/23), and 78% (18/23), with uniformly high positive predictive values of 93% (13/14), 100% (10/10), and 95% (18/19), respectively. We identified 2 distinctly abnormal scintigraphic patterns of focal and uniform (18)F-FDG uptake corresponding to nodular and diffuse peritoneal disease on pathologic examination. CONCLUSION: (18)F-FDG PET adds to conventional imaging in the staging of peritoneal carcinomatosis. It is also a useful diagnostic tool when peritoneal biopsy is either unavailable or inappropriate. We have identified 2 distinct scintigraphic patterns that appear to predict the presence of either nodular or diffuse peritoneal pathology.     

Clinical utility of 18F-FDG PET for patients with salivary gland malignancies.

The clinical utility of 18F-FDG PET in evaluating salivary gland malignancies has not been well defined. We therefore evaluated the utility of 18F-FDG PET in management for patients with salivary gland cancers. METHODS: Thirty-four patients with newly diagnosed salivary gland cancers underwent CT and 18F-FDG PET before surgical resection with radiotherapy. The diagnostic accuracies of CT and 18F-FDG PET for detecting primary tumors and neck metastases were compared with a histopathologic reference. We determined the relationship between the maximum standardized uptake value (SUV) of the tumor and clinicopathologic parameters such as sex, age, local tumor invasion, T and N categories, TNM stage, and histologic grade, as well as their associations with disease-free survival (DFS). RESULTS: 18F-FDG PET was more sensitive than CT for the detection of primary tumors (91.2% vs. 79.4%; P < 0.05), cervical metastases (80.5% vs. 56.1%; P < 0.05), and distant metastases in 2 patients at initial staging. High-grade malignancies had higher mean maximum SUVs than did low- and intermediate-grade malignancies (4.6 vs. 2.8; P = 0.011). T and N categories were independent determinants of DFS (P < 0.05), but the maximum SUV (4.0) was not. During a mean follow-up of 25.1 mo, 18F-FDG PET correctly diagnosed local-regional recurrences in 6 patients and new distant metastases in 9 patients. CONCLUSION: Our findings indicate that, in patients with salivary gland malignancies, 18F-FDG PET is clinically useful in initial staging, histologic grading, and monitoring after treatment but not in predicting patient survival.     

Routine (18)F-FDG PET preoperative staging of colorectal cancer: comparison with conventional staging and its impact on treatment decision making.

The preoperative staging of colorectal cancer (CRC) with (18)F-FDG PET is not as yet generally considered to be evidence based. We have found only 1 study that evaluated (18)F-FDG PET in a nonselected population with proven CRC. Several other studies have concentrated on more advanced disease. The aim of this study was to assess the potential clinical benefit of (18)F-FDG PET in the routine staging of CRC. METHODS: Thirty-eight consecutive patients who had had CRC histologically proven by colonoscopy underwent prospective preoperative staging by plain chest radiography, sonography, CT, and (18)F-FDG PET. Sensitivity, specificity, and accuracy were retrospectively assessed by comparison with the histologic results after surgery (36 patients) or clinical follow-up (2 inoperable cases-both patients died within 1 y of the PET examination). The impact of (18)F-FDG PET on therapeutic decision making was evaluated by comparing medical records before and after (18)F-FDG PET. RESULTS: (18)F-FDG PET correctly detected 95% of primary tumors, whereas CT and sonography correctly detected only 49% and 14%, respectively. Lymph nodes were involved in 7 patients. The sensitivity, specificity, and accuracy of (18)F-FDG PET were 29%, 88%, and 75%, respectively. CT and sonography did not reveal any lymph node involvement. Liver metastases were present in 9 patients. (18)F-FDG PET, CT, and sonography had a sensitivity of 78%, 67%, and 25%, respectively; a specificity of 96%, 100%, and 100%, respectively; and an accuracy of 91%, 91%, and 81%, respectively. (18)F-FDG PET revealed further lesions in 11 patients. Levels of carcinoembryonic antigen and carbohydrate antigen 19-9 tumor markers were elevated in, respectively, only 33% and 8% of cases of proven CRC. (18)F-FDG PET changed the treatment modality for 8% and the range of surgery for 13% of patients. In total, (18)F-FDG PET changed the method of treatment for 16% of patients. CONCLUSION: Plain chest radiography and sonography did not bring any clinical benefits. No correlation was found between the level of tumor markers and the stage of disease. CT is necessary for confirmation of PET findings at extraabdominal sites (PET-guided CT) and for their morphologic specification at abdominal and pelvic sites before an operation. (18)F-FDG PET is the best method for the staging of CRC in all localities, despite the high rate of false-negative PET findings in patients with lymph node involvement. PET should be performed as a first examination after verification of CRC. We propose a PET/CT hybrid system as optimal in the staging of CRC.     

18F-氟脱氧葡萄糖PET在恶性淋巴瘤中的应用

CT是诊断恶性淋巴瘤常规影像学手段,核医学显像也是非常重要的检查方法,如67Ga显像.18F-氟脱氧葡萄糖(18SF-FDG)PET以其在淋巴瘤中应用的显著优势逐步替代了67Ga显像.18F-FDG PET在淋巴瘤的早期诊断、准确分期、疗效的评价、复发和预后的估计等方面显示出了非常重要的价值.随着PET-CT的广泛应用使得敏感性和特异性都有了进一步的提高.主要综述了18F-FDG PET在淋巴瘤诊断、分期、疗效评价中的应用.     

Yield of brain 18F-FDG PET in evaluating patients with potentially operable non-small cell lung cancer.

The American College of Surgeons Oncology Group recently completed a trial evaluating the role of PET with 18F-FDG in patients with documented or suspected non-small cell lung cancer. Subjects underwent standard imaging to exclude metastatic disease before PET. Here, we report the yield of brain PET in evaluating, for potential intracranial metastases, patients who have undergone previous brain CT or MRI with negative findings. METHODS: A total of 287 evaluable patients who had been registered from 22 institutions underwent whole-body 18F-FDG PET, including dedicated PET of the brain, after routine staging procedures had found no suggestion of metastatic disease. Patients were followed postoperatively for disease-free and overall survival, with a minimum follow-up of 6 mo. Patients with specific brain abnormalities identified by PET were further examined, and the findings were evaluated along with the results of CT and MRI, clinical management, and follow-up. RESULTS: In 4 patients, PET found focal 18F-FDG uptake in the brain suggestive of metastatic disease; however, metastatic disease was excluded clinically in all 4 by negative findings on further brain imaging. All 4 patients remained alive at follow-up (mean duration, 10.5 mo; range, 6-16 mo). CONCLUSION: In patients with suspected or proven non-small cell lung cancer considered resectable by standard imaging, including routine preoperative contrast-enhanced CT or MRI of the brain, PET of the brain provides no additional information regarding metastatic disease.     

Early prediction of response to chemotherapy in metastatic breast cancer using sequential 18F-FDG PET.

Chemotherapy is currently the treatment of choice for patients with high-risk metastatic breast cancer. Clinical response is determined after several cycles of chemotherapy by changes in tumor size as assessed by conventional imaging procedures including CT, MRI, plain film radiography, or ultrasound. The aim of this study was to evaluate the use of sequential 18F-FDG PET to predict response after the first and second cycles of standardized chemotherapy for metastatic breast cancer. METHODS: Eleven patients with 26 metastatic lesions underwent 31 (18)F-FDG PET examinations (240-400 MBq of 18F-FDG; 10-min 2-dimensional emission and transmission scans). Clinical response, as assessed by conventional imaging after completion of chemotherapy, served as the reference. 18F-FDG PET images after the first and second cycles of chemotherapy were analyzed semiquantitatively for each metastatic lesion using standardized uptake values (SUVs) normalized to patients' blood glucose levels. In addition, whole-body 18F-FDG PET images were viewed for overall changes in the 18F-FDG uptake pattern of metastatic lesions within individual patients and compared with conventional imaging results after the third and sixth cycles of chemotherapy. RESULTS: After completion of chemotherapy, 17 metastatic lesions responded, as assessed by conventional imaging procedures. In those lesions, SUV decreased to 72% +/- 21% after the first cycle and 54% +/- 16% after the second cycle, when compared with the baseline PET scan. In contrast, 18F-FDG uptake in lesions not responding to chemotherapy (n = 9) declined only to 94% +/- 19% after the first cycle and 79% +/- 9% after the second cycle. The differences between responding and nonresponding lesions were statistically significant after the first (P = 0.02) and second (P = 0.003) cycles. Visual analysis of 18F-FDG PET images correctly predicted the response in all patients as early as after the first cycle of chemotherapy. As assessed by 18F-FDG PET, the overall survival in nonresponders (n = 5) was 8.8 mo, compared with 19.2 mo in responders (n = 6). CONCLUSION: In patients with metastatic breast cancer, sequential 18F-FDG PET allowed prediction of response to treatment after the first cycle of chemotherapy. The use of 18F-FDG PET as a surrogate endpoint for monitoring therapy response offers improved patient care by individualizing treatment and avoiding ineffective chemotherapy.     

Diagnostic accuracy of 18F-FDG PET/CT in characterizing ovarian lesions and staging ovarian cancer: correlation with transvaginal ultrasonography, computed tomography, and histology

AIMS: To (a) assess the accuracy of 18F-FDG PET/CT in distinguishing malignant from benign pelvic lesions, compared to transvaginal ultrasonography (TVUS) and (b) to establish the role of whole-body 18F-FDG PET/CT, compared to contrast enhanced computed tomography (CT), in staging patients with ovarian cancer. PATIENTS: Fifty consecutive patients with a pelvic lesion, already scheduled for surgery on the basis of physical examination, TVUS, and serum Ca125 levels, were enrolled in the study. Patients' age ranged between 23 and 89 years (mean 64). All patients underwent TVUS including a colour Doppler study followed by a thorax and abdominal CT scan, and whole-body 18F-FDG PET/CT within 2 weeks prior to surgery. Histological findings obtained at surgery were taken as the 'gold standard' to compare 18F-FDG PET/CT and TVUS, and 18F-FDG PET/CT vs. CT. When tissue analysis showed ovarian cancer, the accuracy of 18F-FDG PET/CT and CT were compared for the purpose of obtaining a precise staging. RESULTS: At surgery, the ovarian lesions were malignant in 32/50 patients (64%) and benign in the remaining 18/50 patients (36%). The sensitivity, specificity, NPV, PPV and accuracy of 18F-FDG PET/CT were 87%, 100%, 81%, 100% and 92%, respectively, compared with 90%, 61%, 78%, 80% and 80%, respectively, for TVUS. In staging ovarian cancer, 18F-FDG PET/CT results were concordant with final pathological staging in 22/32 (69%) patients while CT results were concordant in 17/32 (53%) patients. CT incorrectly down-staged four out of six stage IV patients by missing distant metastasis in the liver, pleura, mediastinum, and in left supraclavicular lymph nodes, which were correctly detected by 18F-FDG PET/CT. CONCLUSION: PET/CT with 18F-FDG provides additional value to TVUS for the differential diagnosis of benign from malignant pelvic lesions, and to CT for the staging of ovarian cancer patients.     

18F-FDG PET/CT在黑色素瘤中的应用价值

目的 探讨18F-脱氧葡萄糖(FDG)PET/CT显像在黑色素瘤诊断、临床分期及监测治疗后肿瘤复发与转移灶中的应用价值.方法 黑色素瘤患者61例,均进行18F-FDG PET/CT全身显像.所有PET、CT及PET/CT融合图像均通过融合软件进行帧对帧对比分析.肿瘤病灶根据病理学检查、多种影像学检查及临床随访结果诊断.结果 18F-FDG PET/CT显像对黑色素瘤病灶检出的灵敏度、特异性和准确性分别为90.9%(40/44)、88.2%(15/17)和90.2%(55/61).其中12例治疗前患者中,18F-FDG PET/CT显像诊断的灵敏度为83.3%(10/12).在黑色素瘤病灶局部切除、尚未进行其他治疗的9例患者中,5例残余病灶18F-FDG PET/CT显像检出3例;4例远处转移灶患者全被检出,提高了临床分期,改变了治疗方案.首先发现转移性黑色素瘤病灶并且手术切除后,寻找原发灶的7例患者中,18F-FDG PET/CT检出原发灶2例,4例其他转移灶全被检出.黑色素瘤患者根治术后监测肿瘤复发或转移患者33例,18F-FDG PET/CT显像灵敏度、特异性和准确性分别为100.0%(19/19)、85.7%(12/14)和93.9%(31/33).与同期临床其他影像学检查比较,18F-FDG PET/CT显像发现更多,33例患者中,16例(48.5%)病灶提高临床分期;7例(21.2%)排除可疑病灶,降低临床分期;10例(30.3%)检出病灶与临床一致.结论 18F-FDG PET/CT显像对于黑色素瘤的诊断,残余病灶、复发病灶及转移灶的检出,临床分期的明确具有重要价值.     

Usefulness of 18F-FDG PET/CT for the Evaluation of Bone Marrow Involvement in Patients with High-Grade Non-Hodgkin’s Lymphoma

Purpose

To assess the usefulness of ¹⁸F-fluorodeoxyglucose PET/CT in the detection of bone marrow (BM) involvement of high-grade non-Hodgkin’s lymphoma (NHL).

Methods

One hundred twenty patients with newly diagnosed diffuse large B-cell lymphoma or peripheral T-cell lymphoma between January 2007 and June 2011, who received BM trephine biopsy and ¹⁸F-FDG PET/CT before chemotherapy, were included in this retrospective study. We reviewed their ¹⁸F-FDG PET/CT images and bone marrow biopsy (BMB) results. After reviewing the images, we reviewed the medical records and radiological findings of interesting patients.

Results

There were 23 ¹⁸F-FDG PET/CT scans in which the marrow was considered to be abnormal (either positive or equivocal), and 97 ¹⁸F-FDG PET/CT scans were regarded as having negative FDG uptake. Of 120 patients, 100 (83.3 %) had a concordant result of BM interpretation between ¹⁸F-FDG PET/CT and BMB, and the remaining 20 patients had discordant results. Among 23 patients with either positive or equivocal ¹⁸F-FDG PET/CT scans, 1 of 12 patients with ‘positive’ ¹⁸F-FDG PET/CT had a lymphomatous involvement on BMB. In contrast, 10 of 11 patients with ‘equivocal’ BM hypermetabolism were reported as having positive involvement by BMB. Patients with abnormal ¹⁸F-FDG PET/CT had significantly higher mSUV_highest than those with normal FDG-PET/CT.

Conclusions

¹⁸F-FDG PET/CT and BMB are complementary techniques in assessing the presence of BM involvement in patients with high-grade NHL. The increasing availability of ¹⁸F-FDG PET/CT will raise the need for additional biopsy for FDG-avid lesions, especially in patients with negative standard BMBs. ¹⁸F-FDG PET/CT can be useful as a decision-making tool for determining whether to perform a standard BMB or targeted biopsy to the FDG-avid lesion as an initial staging procedure. A direct bone biopsy for FDGpositive bone lesions should be included in staging guidelines in future. In ¹⁸F-FDG PET/CT-negative cases, BMB is still a powerful procedure, but BMB alone is insufficient for full evaluation of BM.     

Role of 18F-FDG PET/CT in staging and follow-up of lymphoma in pediatric and young adult patients

OBJECTIVE: To assess the role of 18F-Fluorodeoxyglucose (18F-FDG) PET/CT in pediatric patients with Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL). MATERIALS AND METHODS: 31 patients, mean age 12.9 +/- 5.1, HD (n = 24), and NHL (n = 7) underwent 18F-FDG PET/CT at diagnosis (n = 31 studies) and later in the course of the disease (n = 75 studies). The findings of PET/CT were correlated with diagnostic CT and clinical follow-up. RESULTS: PET/CT findings resulted in a change of disease staging in 10 patients (32.3%), upstaging in 7 (22.6%) and downstaging in 3 (9.6%). On a lesion analysis, 164 disease sites were detected by PET/CT of which 38 were overlooked by DCT.At mid-treatment, PET was negative in 28 out of 31 patients (90%) with negative predictive value of 96% as all latter patients except for 1, were disease free (mean 15.4 +/- 8.8 months). The positive predictive value of persistent increased 18F-FDG uptake was 100% as 3 patients with latter findings had active disease. On the CT part, 76 residual masses were identified in 22 patients. Increased 18F-FDG uptake was detected in 11 masses in 4 patients who had active disease. Remaining 65 PET negative masses were false positive findings. The positive predictive value of residual CT mass was 14%. CONCLUSIONS: PET/CT is associated with change in staging in approximately 1 out of 3 pediatric patients with HD and NHL. When used for monitoring response to treatment, a negative study is associated with disease-free period, even when residual mass is detected. A positive PET study indicates residual malignant disease.     

18F-FDG PET in evaluation of adrenal lesions in patients with lung cancer.

The purpose of this study was to assess the role of PET with (18)F-FDG in differentiating benign from metastatic adrenal masses detected on CT or MRI scans of patients with lung cancer. METHODS: This retrospective study analyzed (18)F-FDG PET scans of patients with lung cancer who were found to have an adrenal mass on CT or MRI scans. One hundred thirteen adrenal masses (75 unilateral and 19 bilateral; size range, 0.8-4.7 cm) were evaluated in 94 patients. PET findings were interpreted as positive if the (18)F-FDG uptake of the adrenal mass was greater than or equal to that of the liver. PET findings were interpreted as negative if the (18)F-FDG uptake of the adrenal mass was less than that of the liver. All studies were reviewed independently by 3 nuclear medicine physicians, and the results were then correlated with clinical follow-up or biopsy results when available. RESULTS: PET findings were positive in 71 adrenal masses. Sixty-seven of these were eventually considered to be metastatic adrenal disease. In the remaining 4, no changes in lesion size were noted on follow-up examinations. PET findings were negative in 42 adrenal masses, of which 37 eventually proved to be benign. Among the 5 adrenal masses that were false-negative, one was a large necrotic metastasis; 1 was a 2.4-cm lesion with central hemorrhaging, and the remaining 3 were lesions of less than 11 mm. The sensitivity, specificity, and accuracy for detecting metastatic disease were 93%, 90%, and 92%, respectively. CONCLUSION: (18)F-FDG PET is an accurate, noninvasive technique for differentiating benign from metastatic adrenal lesions detected on CT or MRI in patients with lung cancer. In addition, PET has the advantage of assessing the primary cancer sites and detecting other metastases.