Impact of computed tomography (CT) and 18F-deoxyglucose-coincidence detection emission tomography (FDG-CDET) image fusion for optimisation of conformal radiotherapy in non-small-cell lung cancers]

To report a retrospective study concerning the impact of fused 18F-fluorodeoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on three-dimensional conformal radiation therapy (3D-CRT) planning for patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: One hundred and one patients consecutively treated for stages I-III NSCLC were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define target volume. RESULTS: FDG-PET identified previously undetected distant metastatic disease in 8 patients making them ineligible for curative CRT (one patient presented some positive uptakes corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because fused CT/PET images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT/PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT/PET image fusion reduced pulmonary GTV in 6 patients (3 patients with atelectasis) and mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients due to an increase of the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Among 81 patients receiving a total dose > or = 60 Gy at ICRU point, after CT/PET image fusion, the percentage of total lung volume receiving more than 20 Gy (VL20) increased in 15 cases and decreased in 22 cases. The percentage of total heart volume receiving more than 36 Gy increased in 8 patients and decreased in 14 patients. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. After multivariate analysis, one single independent factor made significant effect of FDG/PET on the modification of the size of the GTV: tumor with atelectasis (P = 0.0001). Conclusion. - Our study confirms that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of patients with NSCLC. FDG images using dedicated PET scanners with modern image fusion techniques and respiration-gated acquisition protocols could improve CT/PET image coregistration. However, prospective studies with histological correlation are necessary and the impact on treatment outcome remains to be demonstrated.     

Can post-RT neck dissection be omitted for patients with head-and-neck cancer who have a negative PET scan after definitive radiation therapy?

PURPOSE: A prospective, single institution study was conducted to evaluate the role of positron emission tomography with fluoro-deoxyglucose (FDG) before and after definitive radiation therapy for patients with head-and-neck cancer. Correlation with CT or MRI imaging and pathologic findings at the time of planned neck dissection was made. METHODS AND MATERIALS: Twelve patients with AJCC Stages III-IV cancer of the head and neck received CT or MRI and PET imaging before treatment with definitive radiation therapy. One month after completion of treatment, repeat CT or MRI and PET imaging was obtained. All images were reviewed independently by radiologists who were blind to the results of the other modality. Patients then underwent planned neck dissection. Pathologic correlation with posttreatment scans allowed calculation of the sensitivity, specificity, negative predictive value, and the positive predictive value for both CT/MRI and PET. RESULTS: Comparison of CT/MRI to PET obtained before definitive RT revealed both primary tumor and nodal disease were detected by both modalities in all cases where primary tumor was known. After RT, comparison of CT/MRI imaging to findings of neck dissection revealed a sensitivity of 90%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 50%. Comparison of PET imaging with pathologic findings demonstrated sensitivity of 45%, specificity of 100%, positive predictive value of 100%, and a negative predictive value of 14%. CONCLUSIONS: In this small series of patients, the presence of a positive PET 1 month after RT accurately indicated the presence of residual disease in all cases; however, a negative PET indicated absence of disease in only 14%. Further investigation is warranted before FDG-PET should be used to determine whether post-RT neck dissection should be omitted.     

Impact of FDG-PET on radiation therapy volume delineation in non-small-cell lung cancer

PURPOSE: Locoregional failure remains a significant problem for patients receiving definitive radiation therapy alone or combined with chemotherapy for non-small-cell lung cancer (NSCLC). Positron emission tomography (PET) with [(18)F]fluoro-2-deoxy-d-glucose (FDG) has proven to be a valuable diagnostic and staging tool for NSCLC. This prospective study was performed to determine the impact of treatment simulation with FDG-PET and CT on radiation therapy target volume definition and toxicity profiles by comparison to simulation with computed tomography (CT) scanning alone. METHODS: Twenty-six patients with Stages I-III NSCLC were studied. Each patient underwent sequential CT and FDG-PET simulation on the same day. Immobilization devices used for both simulations included an alpha cradle, a flat tabletop, 6 external fiducial markers, and a laser positioning system. A radiation therapist participated in both simulations to reproduce the treatment setup. Both the CT and fused PET/CT image data sets were transferred to the radiation treatment planning workstation for contouring. Each FDG-PET study was reviewed with the interpreting nuclear radiologist before tumor volumes were contoured. The fused PET/CT images were used to develop the three-dimensional conformal radiation therapy (3DCRT) plan. A second physician, blinded to the results of PET, contoured the gross tumor volumes (GTV) and planning target volumes (PTV) from the CT data sets, and these volumes were used to generate mock 3DCRT plans. The PTV was defined by a 10-mm margin around the GTV. The two 3DCRT plans for each patient were compared with respect to the GTV, PTV, mean lung dose, volume of normal lung receiving > or =20 Gy (V20), and mean esophageal dose. RESULTS: The FDG-PET findings altered the AJCC TNM stage in 8 of 26 (31%) patients; 2 patients were diagnosed with metastatic disease based on FDG-PET and received palliative radiation therapy. Of the 24 patients who were planned with 3DCRT, PET clearly altered the radiation therapy volume in 14 (58%), as follows. PET helped to distinguish tumor from atelectasis in all 3 patients with atelectasis. Unsuspected nodal disease was detected by PET in 10 patients, and 1 patient had a separate tumor focus detected within the same lobe of the lung. Increases in the target volumes led to increases in the mean lung dose, V20, and mean esophageal dose. Decreases in the target volumes in the patients with atelectasis led to decreases in these normal-tissue toxicity parameters. CONCLUSIONS: Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in over 50% of patients by comparison with CT targeting. The increasing availability of integrated PET/CT units will facilitate the use of this technology for radiation treatment planning. A confirmatory multicenter, cooperative group trial is planned within the Radiation Therapy Oncology Group.     

Radiation treatment planning with an integrated positron emission and computer tomography (PET/CT): a feasibility study

PURPOSE: To investigate the usefulness of hardware coregistered PET/CT images for target volume definition. METHODS AND MATERIALS: Thirty-nine patients presenting with various solid tumors were investigated. CT and a FDG-PET were obtained in treatment position in an integrated PET/CT scanner, and coregistered images were used for treatment planning. First, volume delineation was performed on the CT data. In a second step, the corresponding PET data were used as an overlay to the CT data to define the target volume. Delineation was done independently by two investigators. RESULTS: Coregistered PET/CT showed good fusion accuracy. The GTV increased by 25% or more because of PET in 17% of cases with head-and-neck (2/12) and lung cancer (1/6), and in 33% (7/21) in cancer of the pelvis. The GTV was reduced > or =25% in 33% of patients with head-and-neck cancer (4/12), in 67% with lung cancer (4/6), and 19% with cancer of the pelvis (4/21). Overall, in 56% (22/39) of cases, GTV delineation was changed significantly if information from metabolic imaging was used in the planning process. The modification of the GTV translated into altered PTV changes exceeding >20% in 46% (18/39) of cases. With PET, volume delineation variability between two independent oncologists decreased from a mean volume difference of 25.7 cm(3) to 9.2 cm(3) associated with a reduction of the standard deviation from 38.3 cm(3) to 13.3 cm(3) (p = 0.02). In 16% of cases, PET/CT revealed distant metastasies, changing the treatment strategy from curative to palliative. CONCLUSION: Integrated PET/CT for treatment planning for three-dimensional conformal radiation therapy improves the standardization of volume delineation compared with that of CT alone. PET/CT has the potential for reducing the risk for geographic misses, to minimize the dose of ionizing radiation applied to non-target organs, and to change the current practice to three-dimensional conformal radiation therapy planning by taking into account the metabolic and biologic features of cancer. The impact on treatment outcome remains to be demonstrated.     

PET/CT in the evaluation of response to treatment of liver metastases from colorectal cancer with bevacizumab and irinotecan

The present approach at our institution for the treatment of patients with colorectal (CRC) cancer and with liver metastases planned for metastasectomy is the neoadjuvant administration of Bevacizumab with Irinotecan based therapy. Metabolic imaging of tumor viability with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), and simultaneous anatomic localization provided by low-dose non-enhanced computed tomography (CT), can be obtained in a combined modality FDG-PET/CT scan. The purpose of this study was to evaluate the possible contribution of FDG-PET/CT as a surrogate marker to evaluate treatment response of liver metastases in vivo. This is a retrospective evaluation of 18F-FDG PET and CT findings in the first seven consecutive patients. FDG-PET/CT scans were performed before the start of the neoadjuvant and after four cycles of therapy, just prior to surgery. Results were compared to concurrent contrast-enhanced CT, when required, and pathology. Response to treatment was determined according to RECIST size criteria obtained from data from thin (3-5mm) slice CT, and changes in uptake of 18F-FDG uptake on PET. A total of 20 liver lesions were evaluated in seven patients. Overall, 6/7 patients had favorable response to treatment, and only one had progression of disease. One patient was found to be inoperable at surgery. Biopsy was obtained in 1/4 lesions in this patient, while pathology was unable for the remaining three lesions. As such, pathologic validation of findings was available for 17/20 lesions. Complete response (CR) was evident on FDG-PET in 10/17 (58%) lesions, whereas only 4/17(23%) were deemed CR by CT. Similarly, only 1/17 (6%) lesion appeared stable by FDG-PET criteria, whereas three (18%) were termed stable disease (SD) according to size on CT. FDG-PET findings correlated better than CT with pathology, and were more indicative of pathology. Overall PET/CT correctly predicted necrosis at pathology in 70% vs. 35% by CT. Our results suggest that 18F-FDG PET may be instrumental for predicting the pathologic response to Bevacizumab based therapy.     

The role of FDG-PET/CT in suspected recurrence of breast cancer

BACKGROUND: Early diagnosis of recurrent breast cancer is crucial to selection of the most appropriate therapy. The current study evaluated the role of FDG-PET/CT in the assessment of suspected recurrent breast cancer in patients who presented with elevated serum tumor markers. METHODS: Forty-seven consecutive FDG-PET/CT studies of 46 women (aged 32-79 years; mean, 59.9 years) with a history of breast cancer presented with elevated serum tumor markers 1-21 years (mean = 6.2 years) after their initial diagnosis and were retrospectively evaluated. PET/CT results were confirmed by pathology (n = 11), further imaging, and follow-up (mean = 17.2 months; n = 36). Changes in further management based on PET/CT were recorded. RESULTS: Thirty (65%) patients had tumor recurrence, and 16 (35%) patients showed no further evidence of disease. Thirty-one patients had 32 abnormal PET/CT studies, and 15 patients had normal studies with an overall sensitivity, specificity, and accuracy of 90%, 71%, and 83%, respectively. In 37 patients, PET/CT was compared with contrast-enhanced CT and had a higher sensitivity (85% vs 70%), specificity (76% vs 47%), and accuracy (81% vs 59%). PET/CT had an impact on the management of 24 (5l%) patients. Of these, chemotherapy or radiotherapy was started in 16 patients, treatment was modified in 2 patients, and 6 patients were referred to biopsy, followed by referral to surgery for 2 patients. CONCLUSIONS: In patients with breast cancer and rising tumor markers, FDG-PET/CT had high performance indices and was superior to CT for diagnosis of tumor recurrence, which led to changes in the subsequent clinical management of 51% of these patients.     

Impact of computed tomography (CT) and 18F-deoxyglucose positron emission tomography (FDG-PET) image fusion for conformal radiotherapy in esophageal carcinoma]

PURPOSE: To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiation therapy (CRT) planning for patients with esophageal carcinoma. PATIENTS AND METHODS: Thirty-four patients with esophageal carcinoma were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same radiation treatment position. PET-images were coregistered using five fiducial markers. Target delineation was initially performed on CT images and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. RESULTS: FDG-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative CRT. The Gross Tumor Volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and was increased in 7 patients (20.5%). The GTV reduction was >or=25% in 4 patients due to reduction of the length of the esophageal tumor. The GTV increase was >or=25% with FDG-PET in 2 patients due to the detection of occult mediastinal lymph node involvement in one patient and an increased length of the esophageal tumor in the other patient. Modifications of the GTV affected the planning treatment volume (PTV) in 18 patients. Modifications of delineation of GTV and displacement of the isocenter of PTV by FDG-PET also affected the percentage of total lung volume receiving more than 20 Gy (VL20) in 25 patients (74%), with a dose reduction in 12 patients and a dose increase in 13 patients. CONCLUSION: In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of patients with esophageal carcinoma related to modifications of GTV. The impact on treatment outcome remains to be demonstrated.     

The impact of (18)FDG-PET on target and critical organs in CT-based treatment planning of patients with poorly defined non-small-cell lung carcinoma: a prospective study

PURPOSE: To prospectively study the impact of coregistering (18)F-fluoro-deoxy-2-glucose hybrid positron emission tomographic (FDG-PET) images with CT images on the planning target volume (PTV), target coverage, and critical organ dose in radiation therapy planning of non-small-cell lung carcinoma. METHODS AND MATERIALS: Thirty patients with poorly defined tumors on CT, referred for radical radiation therapy, underwent both FDG-PET and CT simulation procedures on the same day, in radiation treatment position. Image sets were coregistered using external fiducial markers. Three radiation oncologists independently defined the gross tumor volumes, using first CT data alone and then coregistered CT and FDG-PET data. Standard margins were applied to each gross tumor volume to generate a PTV, and standardized treatment plans were designed and calculated for each PTV. Dose-volume histograms were used to evaluate the relative effect of FDG information on target coverage and on normal tissue dose. RESULTS: In 7 of 30 (23%) cases, FDG-PET information changed management strategy from radical to palliative. In 5 of the remaining 23 (22%) cases, new FDG-avid nodes were found within 5 cm of the primary tumor and were included in the PTV. The PTV defined using coregistered CT and FDG-PET would have been poorly covered by the CT-based treatment plan in 17--29% of cases, depending on the physician, implying a geographic miss had only CT information been available. The effect of FDG-PET on target definition varied with the physician, leading to a reduction in PTV in 24-70% of cases and an increase in 30-76% of cases. The relative change in PTV ranged from 0.40 to 1.86. On average, FDG-PET information led to a reduction in spinal cord dose but not in total lung dose, although large differences in dose to the lung were seen for a few individuals. CONCLUSION: The coregistration of planning CT and FDG-PET images made significant alterations to patient management and to the PTV. Ultimately, changes to the PTV resulted in changes to the radiation treatment plans for the majority of cases. Where possible, we would recommend that FDG-PET data be integrated into treatment planning of non-small-cell lung carcinoma, particularly for three-dimensional conformal techniques.     

Comparison of five segmentation tools for 18F-fluoro-deoxy-glucose-positron emission tomography-based target volume definition in head and neck cancer

PURPOSE: Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with (18)F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may improve definition of the gross tumor volume (GTV). In this study, five methods for tumor delineation on FDG-PET are compared with CT-based delineation. METHODS AND MATERIALS: Seventy-eight patients with Stages II-IV squamous cell carcinoma of the head and neck area underwent coregistered CT and FDG-PET. The primary tumor was delineated on CT, and five PET-based GTVs were obtained: visual interpretation, applying an isocontour of a standardized uptake value of 2.5, using a fixed threshold of 40% and 50% of the maximum signal intensity, and applying an adaptive threshold based on the signal-to-background ratio. Absolute GTV volumes were compared, and overlap analyses were performed. RESULTS: The GTV method of applying an isocontour of a standardized uptake value of 2.5 failed to provide successful delineation in 45% of cases. For the other PET delineation methods, volume and shape of the GTV were influenced heavily by the choice of segmentation tool. On average, all threshold-based PET-GTVs were smaller than on CT. Nevertheless, PET frequently detected significant tumor extension outside the GTV delineated on CT (15-34% of PET volume). CONCLUSIONS: The choice of segmentation tool for target-volume definition of head and neck cancer based on FDG-PET images is not trivial because it influences both volume and shape of the resulting GTV. With adequate delineation, PET may add significantly to CT- and physical examination-based GTV definition.     

18FDG-positron emission tomography in post treatment evaluation of residual mass in Hodgkin's lymphoma: long-term results

In patients with Hodgkin's lymphoma (HL) at the end of first line therapy an accurate imaging technique with high prognostic value is needed to assess response to treatment and predict those patients who will suffer disease relapse. This technique and its results permit the quick initiation of a second line therapy in patients suffering from a progressive disease or those unresponsive to treatment avoid over-treatment of patients in complete remission or those having a non-active residual disease. We included a (18)FDG-positron emission tomography (PET) scan to the diagnostic set-up to investigate 28 patients following the end of their treatment. Fifteen patients out of the 28 (54%) had positive CT scans while 13 (46%) had negative ones. Eleven patients out of the 15 CT positive (73%) had negative PET scans and no relapse. The remaining four patients (27%) had positive PET scans with only one relapse (25%). With respect to the 13 patients who had negative CT scans, 9 patients (69%) had negative PET scans and no relapse. The remaining 4 patients (31%) had positive PET scans with 3 relapse cases (75%). In our final assessment after a median follow-up period of 45 months, starting from PET execution to the last follow-up, overall sensitivity of the CT and the PET were 25 and 100% respectively, specificity 42 and 83% respectively, positive predictive value (PPV) 7 and 50% respectively, negative predictive value (NPV) 77 and 100% respectively, and accuracy 39 and 86% respectively. In our experience, FDG-PET performed in patients after induction therapy appears to offer important additional information: FDG-PET results are predictors of prognosis giving 100% DFS in PET negative patients and 54% DSF in PET positive patients.     

FDG-PET/CT imaging for preradiotherapy staging of head-and-neck squamous cell carcinoma

PurposeImage localization of head-and-neck squamous cell carcinoma lags behind current techniques to deliver a precise radiation dose with intensity-modulated radiotherapy. This pilot study prospectively examined the use of registered 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT for preradiotherapy staging of the neck.Methods and materialsSixty-three patients with squamous cell carcinoma of the oral cavity, oropharynx, larynx, or hypopharynx were enrolled into an institutional FDG-PET imaging protocol between September 2000 and June 2003. Of these patients, 20 went on to immediate neck dissection surgery and were studied further. Of these 20, 17 (85%) had American Joint Committee on Cancer Stage III or IV disease. All patients underwent preoperative FDG-PET and contrast-enhanced CT of the head and neck. FDG-PET/CT images were created using a nonrigid image registration algorithm developed at the University of Washington. Alternate primary and nodal gross tumor volumes were contoured with radiotherapy treatment planning software, blinded to each other and to the pathology results. One set of volumes was designed with CT guidance alone and the other with the corresponding FDG-PET/CT images. Neck dissection specimens were subdivided into surgical nodal levels intraoperatively, and the histopathologic findings were correlated with the CT and FDG-PET/CT nodal level findings.ResultsFDG-PET/CT detected 17 of 17 heminecks and 26 of 27 nodal zones histologically positive by dissection (100% and 96% sensitivity, respectively). The nodal level staging sensitivity and specificity for FDG-PET/CT was 96% (26 of 27) and 98.5% (68 of 69), respectively. FDG-PET/CT correctly detected nodal disease in 2 patients considered to have node-negative disease by CT alone. Agreement between the imaging results and pathology findings was stronger for FDG-PET/CT (κ 0.95, 95% confidence interval 0.82–0.99) than for CT alone (κ 0.81, 95% confidence interval 0.63–0.91; p = 0.06 by two-sided McNemar's testing).ConclusionThese early findings suggest that FDG-PET/CT is superior to CT alone for geographic localization of diseased neck node levels. Confirmatory trials to substantiate the accuracy of FDG-PET/CT neck staging should be prioritized.     

Impact of fluorine-18 fluorodeoxyglucose positron emission tomography on patient management: first year's experience in a clinical center.

PURPOSE: To measure the impact of whole-body fluorodeoxyglucose (FDG) positron emission tomography (PET) on patient management during its first year of use in a community hospital. MATERIALS AND METHODS: First-year FDG-PET impact was determined from 463 referring physicians' evaluations of their patients' PET imaging results using two surveys. Survey 1 was given to all physicians referring patients to PET to discover whether PET changed patient management or had decision-making value in the patient's clinical algorithm. Survey 2 was given to one surgeon and one pulmonologist after therapy to determine how PET affected the surgical, chemotherapeutic, and/or radiotherapeutic treatment for the 53 cancer patients they referred. RESULTS: The 463 responses to survey 1 described 23 different PET indications. Lung (40%), head and neck (18%), and colorectal cancers (11%) were the three leading causes of referral. PET changed patient management/therapy in 45% of all patients referred and had inferential/decision-making value in another 44%. Overall, PET had some type of positive influence in 412 (89%) of the patients. Survey 2 provided a more detailed assessment of 53 referrals from two specialists. PET positively affected surgery in 31 patients (58%), prompted the addition of chemotherapy or radiation therapy in nine patients (17%), and eliminated chemotherapy or radiation therapy in four cases (8%). Overall, PET affected patient management/therapy in 70% of the cases and had some decision-making value in another 26%, for a combined PET impact on patient management of 96%. CONCLUSION: FDG-PET can be valuable for physicians in clinical practice. Its sensitivity and specificity in metabolic imaging, when combined with complementary anatomic imaging techniques, contribute significantly to the clinical treatment of cancer patients. In addition, the high accuracy of FDG-PET makes it a cost-effective radiologic procedure in the work-up of all suspected and/or recurrent cancer patients. Further research is needed to link this demonstrated impact on patient management to cost-effectiveness.     

18FDG-Positron emission tomography for the early prediction of response in advanced soft tissue sarcoma treated with imatinib mesylate (Glivec)

Imatinib mesylate (Glivec, formerly STI571) is the first effective systemic treatment for gastrointestinal stromal tumours (GISTs). Major changes in tumour volume, however, tend to occur late after the start of treatment. The aim of this study was to evaluate if [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) can be used for the early evaluation of response to imatinib mesylate treatment in soft-tissue sarcomas (STS). 21 patients (17 GIST, 4 other STS) underwent FDG-PET imaging prior to and 8 days after the start of treatment. PET response (European Organization for Research and Treatment (EORTC) guidelines) was observed in 13 GISTs (11 Complete Responders, 2 partial responders. Subsequent computerised tomography (CT) response Response Evaluation Criteria in Solid Tumours (RECIST) was observed in 10 of these patients after a median follow up of 8 weeks. Stable or progressive disease was observed on PET in 8 patients and none of them achieved a response on CT. PET response was also associated with a longer progression-free survival (PFS) (92% versus 12% at 1 year, P=0.00107). We conclude that FDG-PET is an early and sensitive method to evaluate an early response to imatinib treatment.     

Positron Emission Tomography with 18-Fluorodeoxyglucose in the Staging and Follow-up of Lymphoma in the Chest

The purpose of this retrospective study was to evaluate the accuracy of positron emission tomography (PET) using 18-F-fluorodeoxyglucose (FDG) in predicting lymphomatous involvement in the hilar and mediastinal regions in the staging and follow-up of patients with malignant lymphoma. One hundred forty-seven thoracic PET studies in 89 consecutive lymphoma patients were reviewed. Static FDG-PET imaging was performed following application of 270 MBq FDG (mean). Results of FDG-PET were compared with the findings of computed tomography (CT) in all patients and clinical follow-up examination. Eighty-nine of 147 (60%) PET studies showed no FDG uptake in the hilar or mediastinal regions, while 58 (40%) studies did detect FDG uptake in these regions. In 52 of 58 abnormal studies (90%), lymphomatous involvement of the hilar and/or mediastinal regions seen by CT was present. In the remaining six abnormal PET studies (10%), FDG uptake was considered as false-positive because of missing lesions on corresponding CT scans. In four patients false-positive FDG uptake was observed before treatment, in two patients after completion of therapy. In these two patients FDG uptake after therapy was caused by thymus hyperplasia. The remaining four cases before treatment remained unresolved. Sensitivity of FDG-PET was 96%, specificity 94%, positive predictive value 90%, and negative predictive value 98%, respectively. The present study suggests that FDG-PET has potential value in predicting lymphomatous involvement in the hilar and mediastinal regions. FDG-PET may obviate invasive diagnostic procedures in patients with lymphoma.     

Follow-up with 18FDG-PET–CT after radical radiotherapy with or without chemotherapy allows the detection of potentially curable progressive disease in non-small cell lung cancer patients: A prospective study

BackgroundFollow-up of patients treated with curative intent for non-small cell lung cancer (NSCLC) with X-ray or CT-scans is of unproven value. Furthermore, most patients with progressive disease present with symptoms outside of follow-up visits. Because the accuracy of ¹⁸FDG-PET–CT is superior to CT, we hypothesised that FDG-PET–CT scans 3 months post-treatment could lead to early detection of progressive disease (PD) amenable for radical treatment.Patients and methodsHundred patients with NSCLC, treated with curative intent with (chemo) radiation, were prospectively evaluated. All patients underwent a planned FDG-PET–CT scan 3 months after the start of radiotherapy.ResultsTwenty four patients had PD 3 months post-treatment. 16/24 patients were symptomatic. No curative treatment could be offered to any of these patients. In 3/8 asymptomatic patients progression, potentially amenable for radical therapy was found, which were all detected with PET, not with CT only.ConclusionsPET-scanning after curative treatment for NSCLC led to the detection of progression potentially amenable for radical treatment in a small proportion (3%) of patients. Selectively offering a PET–CT scan to the patient group without symptoms could possibly lead to an effective follow-up method.     

Utility of PET/CT imaging performed early after surgical resection in the adjuvant treatment planning for head and neck cancer

PURPOSE: To evaluate the utility of positron emission tomography (PET)/computed tomography (CT) early after surgical resection and before postoperative adjuvant radiation therapy. METHODS AND MATERIALS: We studied a prospective cohort of 91 consecutive patients referred for postoperative adjuvant radiation therapy after complete surgical resection. Tumor histologies included 62 squamous cell and 29 non-squamous cell cancers. Median time between surgery and postoperative PET/CT was 28 days (range, 13-75 days). Findings suspicious for persistent/recurrent cancer or distant metastasis were biopsied. Correlation was made with changes in patient care. RESULTS: Based on PET/CT findings, 24 patients (26.4%) underwent biopsy of suspicious sites. Three patients with suspicious findings did not undergo biopsy because the abnormalities were not easily accessible. Eleven (45.8%) biopsies were positive for cancer. Treatment was changed for 14 (15.4%) patients (11 positive biopsy and 3 nonbiopsied patients) as a result. Treatment changes included abandonment of radiation therapy and switching to palliative chemotherapy or hospice care (4), increasing the radiation therapy dose (6), extending the radiation therapy treatment volume and increasing the dose (1), additional surgery (2), and adding palliative chemotherapy to palliative radiation therapy (1). Treatment for recurrent cancer and primary skin cancer were significant predictors of having a biopsy-proven, treatment-changing positive PET/CT (p < 0.03). CONCLUSIONS: Even with an expectedly high rate of false positive PET/CT scans in this early postoperative period, PET/CT changed patient management in a relatively large proportion of patients. PET/CT can be recommended in the postoperative, preradiation therapy setting with the understanding that treatment-altering PET/CT findings should be biopsied for confirmation.     

Impact of computed tomography and F-deoxyglucose coincidence detection emission tomography image fusion for optimization of conformal radiotherapy in non–small-cell lung cancer

PURPOSE: To report a retrospective study concerning the impact of fused 18F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and CT images on three-dimensional conformal radiotherapy planning for patients with non-small-cell lung cancer. METHODS AND MATERIALS: A total of 101 patients consecutively treated for Stage I-III non-small-cell lung cancer were studied. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. Images were coregistered using five fiducial markers. Target volume delineation was initially performed on the CT images, and the corresponding FDG-PET data were subsequently used as an overlay to the CT data to define the target volume. RESULTS: 18F-fluoro-deoxy-D-glucose-PET identified previously undetected distant metastatic disease in 8 patients, making them ineligible for curative conformal radiotherapy (1 patient presented with some positive uptake corresponding to concomitant pulmonary tuberculosis). Another patient was ineligible for curative treatment because the fused PET-CT images demonstrated excessively extensive intrathoracic disease. The gross tumor volume (GTV) was decreased by CT-PET image fusion in 21 patients (23%) and was increased in 24 patients (26%). The GTV reduction was > or = 25% in 7 patients because CT-PET image fusion reduced the pulmonary GTV in 6 patients (3 patients with atelectasis) and the mediastinal nodal GTV in 1 patient. The GTV increase was > or = 25% in 14 patients owing to an increase in the pulmonary GTV in 11 patients (4 patients with atelectasis) and detection of occult mediastinal lymph node involvement in 3 patients. Of 81 patients receiving a total dose of > or = 60 Gy at the International Commission on Radiation Units and Measurements point, after CT-PET image fusion, the percentage of total lung volume receiving >20 Gy increased in 15 cases and decreased in 22. The percentage of total heart volume receiving >36 Gy increased in 8 patients and decreased in 14. The spinal cord volume receiving at least 45 Gy (2 patients) decreased. Multivariate analysis showed that tumor with atelectasis was the single independent factor that resulted in a significant effect on the modification of the size of the GTV by FDG-PET: tumor with atelectasis (with vs. without atelectasis, p = 0.0001). CONCLUSION: The results of our study have confirmed that integrated hybrid PET/CT in the treatment position and coregistered images have an impact on treatment planning and management of non-small-cell lung cancer. However, FDG images using dedicated PET scanners and respiration-gated acquisition protocols could improve the PET-CT image coregistration. Furthermore, the impact on treatment outcome remains to be demonstrated.     

Impact of CT and 18F-deoxyglucose positron emission tomography image fusion for conformal radiotherapy in esophageal carcinoma

PURPOSE: To study the impact of fused (18)F-fluoro-deoxy-D-glucose (FDG)-hybrid positron emission tomography (PET) and computed tomography (CT) images on conformal radiotherapy planning for esophageal carcinoma patients. METHODS AND MATERIALS: Thirty-four esophageal carcinoma patients were referred for concomitant radiotherapy and chemotherapy with radical intent. Each patient underwent CT and FDG-hybrid PET for simulation treatment in the same treatment position. PET images were coregistered using five fiducial markers. Target delineation was initially performed on CT images, and the corresponding PET data were subsequently used as an overlay to CT data to define the target volume. RESULTS: (18)F-fluorodeoxy-D-glucose-PET identified previously undetected distant metastatic disease in 2 patients, making them ineligible for curative conformal radiotherapy. The gross tumor volume (GTV) was decreased by CT and FDG image fusion in 12 patients (35%) and increased in 7 patients (21%). The GTV reduction was > or =25% in 4 patients owing to a reduction in the length of the esophageal tumor. The GTV increase was > or =25% with FDG-PET in 2 patients owing to the detection of occult mediastinal lymph node involvement in 1 patient and an increased length of the esophageal tumor in 1 patient. Modifications of the GTV affected the planning treatment volume in 18 patients. Modifications of the delineation of the GTV and displacement of the isocenter of the planning treatment volume by FDG-PET also affected the percentage of total lung volume receiving >20 Gy in 25 patients (74%), with a dose reduction in 12 patients and dose increase in 13. CONCLUSION: In our study, CT and FDG-PET image fusion appeared to have an impact on treatment planning and management of esophageal carcinoma. The affect on treatment outcome remains to be demonstrated.     

Value of PET/CT versus enhanced CT for locoregional lymph nodes in non-small cell lung cancer

PURPOSE: To compare the diagnostic efficacies of integrated (18)F FDG PET/CT images and contrast-enhanced helical CT images in locoregional lymph node metastasis in the patients with non-small cell lung cancer (NSCLC). METHODS: From June 2005 to June 2007, 122 potentially operable patients with proven or suspected non-small cell lung cancer underwent integrated PET/CT and contrast-enhanced CT scans followed by surgical nodal staging. The results of reviewing PET/CT and enhanced CT images for the locoregional lymph node metastasis were compared in relation to pathologic findings. RESULTS: Preoperative nodal staging was compared with postoperative histopathological staging, 80% (98 of 122) of patients correctly staged, 13% (16 of 122) of patients were overstaged, and 7% (8 of 122) were understaged by PET/CT, while those values for CT were 56% (68 of 122), 26% (32 of 122), and 18% (22 of 122), respectively. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT for lymph nodes were 86%, 85%, 85%, 64%, 95%, respectively; compared with 69%, 71%, 70%, 43%, 88% for CT (P=0.000, 0.000, 0.000, 0.001, 0.001, respectively). 81% false-negative interpretations and 72% false-positive interpretations on CT were corrected by PET/CT. 57% false-negative interpretations and 45% false-positive interpretations on PET/CT were corrected by CT. 6 % (9 of 153) positive lymph nodes and 8% (40 of 486) negative nodes at pathology were incorrectly diagnosed both by PET/CT and CT. CONCLUSION: Integrated PET/CT improves the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value than enhanced CT in the assessment of locoregional lymph nodes, and provides more efficient and accurate data of nodal staging, with a better effect on diagnosis and therapy in non-small cell lung cancer.     

2-[18F]fluoro-2-deoxyglucose positron-emission tomography in staging, response evaluation, and treatment planning of lymphomas

2-[18F]fluoro-2-deoxyglucose positron-emission tomography (FDG-PET) is used increasingly in the clinical management of lymphomas. With regard to staging, FDG-PET is more sensitive and specific than conventional staging methods in FDG avid lymphomas (ie, Hodgkin lymphoma and most aggressive non-Hodgkin lymphomas). Despite methodological problems, in particular the lack of a valid reference test, FDG-PET is approved and generally used for this purpose. With regard to response evaluation, FDG-PET at the end of treatment seems to aid considerably in differentiating between residual masses with or without residual lymphoma. Hence, new revised response criteria have been proposed, incorporating the result of FDG-PET at the end of treatment. An early interim FDG-PET scan after 1 to 3 cycles of chemotherapy is a very strong predictor of outcome, and trials are now in progress testing treatment modifications on this basis. With regard to treatment planning, in the context of combined-modality therapy, radiotherapy for lymphomas is moving toward more conformal techniques reducing the irradiated volume to include only the macroscopic lymphoma. In this situation, accurate imaging is essential, and FDG-PET coregistered with the planning computed tomography (CT) scan is used increasingly. The availability of PET/CT scanners suited for virtual simulation has aided this process. However, clinical data evaluating this technique are at present sparse.