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Farrokh Dehdashti

Publications and source records attributed to Farrokh Dehdashti.

At least 19 recordsLinked to original sources
PubMed2006

FDG-PET/CT in the evaluation of anal carcinoma.

PURPOSE: Surgical staging and treatment of anal carcinoma has been replaced by noninvasive staging studies and combined modality therapy. In this study, we compare computed tomography (CT) and physical examination to [(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in the staging of carcinoma of the anal canal, with special emphasis on determination of spread to inguinal lymph nodes. METHODS AND MATERIALS: Between July 2003 and July 2005, 41 consecutive patients with biopsy-proved anal carcinoma underwent a complete staging evaluation including physical examination, CT, and 2-FDG-PET/CT. Patients ranged in age from 30 to 89 years. Nine men were HIV-positive. Treatment was with standard Nigro regimen. RESULTS: [(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) detected 91% of nonexcised primary tumors, whereas CT visualized 59%. FDG-PET/CT detected abnormal uptake in pelvic nodes of 5 patients with normal pelvic CT scans. FDG-PET/CT detected abnormal nodes in 20% of groins that were normal by CT, and in 23% without abnormality on physical examination. Furthermore, 17% of groins negative by both CT and physical examination showed abnormal uptake on FDG-PET/CT. HIV-positive patients had an increased frequency of PET-positive lymph nodes. CONCLUSION: [(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography detects the primary tumor more often than CT. FDG-PET/CT detects substantially more abnormal inguinal lymph nodes than are identified by standard clinical staging with CT and physical examination.

Adult↗
PubMed2006

18F-FDG PET definition of gross tumor volume for radiotherapy of non-small cell lung cancer: is a single standardized uptake value threshold approach appropriate?

UNLABELLED: PET with (18)F-FDG has been used in radiation treatment planning for non-small cell lung cancer (NSCLC). Thresholds of 15%-50% the maximum standardized uptake value (SUV(max)) have been used for gross tumor volume (GTV) delineation by PET (PET(GTV)), with 40% being the most commonly used value. Recent studies indicated that 15%-20% may be more appropriate. The purposes of this study were to determine which threshold generates the best volumetric match to GTV delineation by CT (CT(GTV)) for peripheral NSCLC and to determine whether that threshold can be generalized to tumors of various sizes. METHODS: Data for patients who had peripheral NSCLC with well-defined borders on CT and SUV(max) of greater than 2.5 were reviewed. PET/CT datasets were reviewed, and a volume of interest was determined to represent the GTV. The CT(GTV) was delineated by using standard lung windows and reviewed by a radiation oncologist. The PET(GTV) was delineated automatically by use of various percentages of the SUV(max). The PET(GTV)-to-CT(GTV) ratios were compared at various thresholds, and a ratio of 1 was considered the best match, or the optimal threshold. RESULTS: Twenty peripheral NSCLCs with volumes easily defined on CT were evaluated. The SUV(max) (mean +/- SD) was 12 +/- 8, and the mean CT(GTV) was 198 cm(3) (97.5% confidence interval, 5-1,008). The SUV(max) were 16 +/- 5, 13 +/- 9, and 3.0 +/- 0.4 for tumors measuring greater than 5 cm, 3-5 cm, and less than 3 cm, respectively. The optimal thresholds (mean +/- SD) for the best match were 15% +/- 6% for tumors measuring greater than 5 cm, 24% +/- 9% for tumors measuring 3-5 cm, 42% +/- 2% for tumors measuring less than 3 cm, and 24% +/- 13% for all tumors. The PET(GTV) at the 40% and 20% thresholds underestimated the CT(GTV) for 16 of 20 and 14 of 20 lesions, respectively. The mean difference in the volumes (PET(GTV) minus CT(GTV) [PET(GTV) - CT(GTV)]) at the 20% threshold was 79 cm(3) (97.5% confidence interval, -922 to 178). The PET(GTV) at the 20% threshold overestimated the CT(GTV) for all 4 tumors measuring less than 3 cm and underestimated the CT(GTV) for all 6 tumors measuring greater than 5 cm. The CT(GTV) was inversely correlated with the PET(GTV) - CT(GTV) at the 20% threshold (R(2) = 0.90, P < 0.0001). The optimal threshold was inversely correlated with the CT(GTV) (R(2) = 0.79, P < 0.0001). CONCLUSION: No single threshold delineating the PET(GTV) provides accurate volume definition, compared with that provided by the CT(GTV), for the majority of NSCLCs. The strong correlation of the optimal threshold with the CT(GTV) warrants further investigation.

Carcinoma, Non-Small-Cell Lung↗
PubMed2005

Preoperative lymph node staging of early-stage cervical carcinoma by [18F]-fluoro-2-deoxy-D-glucose-positron emission tomography.

BACKGROUND: Increasing evidence has documented the value of positron emission tomography (PET) in oncology, but only limited data are available comparing PET findings with the pathologic status of regional lymph nodes in patients with cervical carcinoma. The objective of this study was to determine the sensitivity and specificity of PET in detecting lymph node metastasis in women with early-stage cervical carcinoma. METHODS: The authors performed a retrospective review of all patients with Stage IA-IIA cervical carcinoma who underwent PET before surgery from 1999 to 2004. The status of the regional lymph nodes was correlated with lymph node pathology. RESULTS: Fifty-nine patients were identified. Pelvic lymph node metastases were present in 32% of the patients and were detected by PET with a sensitivity of 53%, a specificity of 90%, a positive predictive value (PPV) of 71%, and a negative predictive value (NPV) of 80%. Paraaortic lymph node disease was present in 9% of patients and was detected by PET with a sensitivity of 25%, a specificity 98%, a PPV of 50%, and an NPV of 93%. The mean size of the tumor deposits was larger in the PET-positive pelvic nodes (15.2 mm; range, 2-35 mm) than in the PET-negative lymph nodes (7.3 mm; range, 0.3-20 mm; P = 0.002). Computed tomography (CT) scans were obtained before surgery in 42 patients. The combined sensitivity of PET and CT in these patients was 75%. PET alone detected 9 (36%) of the positive lymph node groups, whereas CT alone detected 3 (12%) of the positive lymph node groups. Neither PET nor CT detected the positive lymph node groups in 8 patients (32%). CONCLUSIONS: Pathologic validation of PET imaging demonstrated a low sensitivity and a high specificity for PET in patients with early-stage cervical carcinoma.

Female↗
PubMed2005

F-18 fluorodeoxyglucose uptake in primary cervical cancer as an indicator of prognosis after radiation therapy.

PURPOSE: We evaluated the prognostic significance of tumor metabolic activity on pretreatment positron emission tomography using the glucose analog F-18 fluorodeoxyglucose (FDG-PET) in patients with carcinoma of the cervix undergoing radiotherapy with or without concurrent chemotherapy. METHODS: We studied 96 consecutive patients who underwent FDG-PET prior to initiation of radiotherapy with or without concurrent chemotherapy for carcinoma of the cervix. Pretreatment FDG uptake of the primary tumor was assessed with the semiquantitative standardized uptake value (SUV) and correlated with disease-free and overall survival. Survival was estimated by the Kaplan-Meier method. Univariate and multivariate analyses were performed with the logistic likelihood ratio test and the Cox proportional hazards model, respectively. RESULTS.: Five-year disease-free survivals in patients with maximal SUV <10.2 and > or =10.2 were 71% and 52% (P = 0.0289) respectively, while overall survivals were 72% and 69% (P = 0.4), respectively. On multivariate analysis, lymph node metastasis on FDG-PET was found to be predictive of disease-free survival (P < 0.0001). Both the SUV for FDG and FIGO Stage I disease were found to be marginally predictive of disease-free survival (P = 0.055 and P = 0.058, respectively). CONCLUSIONS: FDG uptake within primary cervical cancer, as measured by SUV, is predictive of disease-free survival in patients undergoing radiotherapy for cervical cancer. High FDG uptake may be useful in identifying patients who may require more aggressive initial therapy.

Adult↗
PubMed2005

FDG-PET evaluation of vaginal carcinoma.

PURPOSE: To compare the results of CT and positron emission tomography (PET) and F-18 fluorodeoxyglucose (FDG) in the detection of the primary tumor and lymph node metastases in carcinoma of the vagina. METHODS AND MATERIALS: This was a prospective registry study of 23 consecutive patients with carcinoma of the vagina, in which we respectively compared the results of CT and whole-body FDG-PET. The tumor was clinical Stage II in 16 patients, Stage III in 6, and Stage IVa in 1 patient. The primary tumor ranged in size from 2 to 10 cm (mean 4.9), and 4 patients had palpable groin lymph nodes. All patients were treated with external beam radiotherapy and brachytherapy, 14 received concurrent chemotherapy, and 2 underwent primary tumor excision before the imaging evaluation. The median follow-up was 21 months in those patients alive without disease. Survival was estimated by the Kaplan-Meier method. RESULTS: Of the 21 patients with an intact primary tumor, CT visualized it in 9 (43%). CT also demonstrated abnormally enlarged groin lymph nodes in 3 patients and both groin and pelvic lymph nodes in 1 patient (4 of 23, 17%). FDG-PET identified abnormal uptake in all 21 intact primary tumors (100%). Abnormal uptake was found in the groin lymph nodes in 4 patients, pelvic lymph nodes in 2, and both groin and pelvic lymph nodes in 2 patients (8 of 23, 35%). The 3-year progression-free and overall survival estimate was 73% and 68%, respectively. CONCLUSION: The results of this study have demonstrated that FDG-PET detects the primary tumor and abnormal lymph nodes more often than does CT.

Carcinoma↗
PubMed2005

Dosimetry of 60/61/62/64Cu-ATSM: a hypoxia imaging agent for PET.

PURPOSE: Cu-diacetyl-bis(N4-methylthiosemicarbazone (Cu-ATSM) is an effective marker for the delineation of hypoxic tissue. Dosimetry calculations by the established Medical Internal Radionuclide Dose (MIRD) approach were performed with both animal and patient data. METHODS: Human absorbed dose estimates extrapolated from rat data were based on the biodistribution of 61Cu-ATSM in adult rats. Eighteen tissues were harvested and time-activity curves generated. The measured residence times and the MIRD S-values for 60Cu-ATSM were used to estimate human absorbed doses. The biodistribution of the tracer was directly measured in five patients injected with approximately 480 MBq of 60Cu-ATSM and imaged by positron emission tomography (PET) with a whole-body protocol. The combined data from all patients were used to derive organ residence times, and organ doses were calculated by MIRD methodology for 60Cu-ATSM, 61Cu-ATSM, 62Cu-ATSM, and 64Cu-ATSM. RESULTS: Human absorbed dose estimates extrapolated from rat biodistribution data indicated that the kidneys appeared to be the dose-limiting organ (0.083 mGy/MBq) with a whole-body dose of 0.009 mGy/MBq. Based on the human PET imaging data, the liver appeared as the dose-limiting organ, with an average radiation dose of 0.064 mGy/MBq. The whole-body dose was 0.009 mGy/MBq and the effective dose was 0.011 mSv/MBq. CONCLUSION: These relatively small absorbed doses to normal organs allow for the safe injection of 500-800 MBq of 60Cu-ATSM, which is sufficient for PET imaging in clinical trials.

Absorption↗
PubMed2005

Positron tomographic assessment of androgen receptors in prostatic carcinoma.

PURPOSE: The purpose of this study was to evaluate the feasibility of androgen receptor (AR) imaging with 16beta-[18F]fluoro-5alpha-dihydrotestosterone (FDHT) by positron emission tomography (PET) and to assess the binding selectivity of FDHT to AR in patients with prostate cancer. METHODS: Twenty men (age range 56-87 years) with advanced prostate cancer were studied. All except one had metastatic disease confirmed by biopsy and/or radiological studies. One patient who had radiological findings suggesting a single hepatic metastasis was found to have focal fatty infiltration on biopsy obtained after FDHT-PET and was excluded from further data analysis. FDHT uptake was assessed semiquantitatively by determination of the standardized uptake value (SUV) and tumor-to-muscle ratio (T/M). Additionally, to assess the AR binding selectivity of FDHT, patients with one or more foci of abnormally increased FDHT accumulation were studied after administration of an AR antagonist (flutamide). RESULTS: Conventional imaging demonstrated innumerable lesions in two patients and 43 lesions in the remaining 17 patients with advanced prostate cancer. FDHT-PET was positive in 12 of 19 patients (sensitivity of 63%), including the two patients with innumerable lesions. FDHT-PET detected 24 of 28 known lesions (86%) in the remaining ten patients. In addition, FDHT-PET detected 17 unsuspected lesions in five of these ten patients. All 12 patients with positive FDHT-PET underwent a repeat PET study after receiving flutamide for 1 day (250 mg t.i.d.). In all of these patients, there was a decrease in tumor FDHT uptake after flutamide; the mean (+/- standard deviation) SUV and T/M decreased from 7.0+/-4.7 and 6.9+/-3.9, respectively, to 3.0+/-1.5 and 3.0+/-1.6, respectively (p=0.002). The mean PSA in patients with positive FDHT-PET was significantly higher than that in patients with negative FDHT-PET (p=0.006). CONCLUSION: Our results document the feasibility of PET imaging of prostate cancer with FDHT and suggest that tumor uptake of FDHT is a receptor-mediated process. Positive PET studies were associated with higher PSA levels and thus, presumably, with greater tumor burden.

Adenocarcinoma↗
PubMed2005

Lack of benefit of concurrent chemotherapy in patients with cervical cancer and negative lymph nodes by FDG-PET.

PURPOSE: To compare the outcome of patients with cervical cancer and negative lymph nodes by fluorodeoxyglucose-positron emission tomography (FDG-PET) treated with irradiation (RT) and concurrent chemotherapy or RT alone. METHODS AND MATERIALS: This was a prospective data registry of 65 patients with cervical cancer and negative lymph nodes by whole-body FDG-PET. The tumor stage was IB2 in 11, IIB in 37, and IIIB in 17 patients. RT alone was administered to 15 and RT with concurrent weekly cisplatin to 50 patients. RESULTS: The 5-year overall survival estimate was 85% with RT and 81% with RT and concurrent chemotherapy (p = 0.91). The corresponding 5-year cause-specific survival estimates were 78% and 74% (p = 0.98). The differences in the sites of recurrence (pelvis vs. distant metastasis) were not statistically significant between the two groups (p = 0.77). A Cox proportional hazards model of survival outcome did not identify chemotherapy, overall treatment time, or radiation dose as statistically significant prognostic factors. Severe complications included one rectovaginal fistula, one rectal stricture requiring colostomy (both in the concurrent chemotherapy group), and one death from chemotherapy-related complications. CONCLUSION: Irradiation with concurrent cisplatin was not advantageous compared with RT alone in patients with negative lymph nodes on FDG-PET.

Adenocarcinoma↗
PubMed2005

FDG uptake in colonic villous adenomas.

Colonic adenomas constitute 70-80% of all colorectal polyps, and their clinical significance relates primarily to their relationship with colorectal cancer. The malignant potential of the polyps detected by FDG-PET is unknown, as not all the colonic lesions identified by FDG-PET represent colorectal malignancies. The purpose of this study was to investigate the rate of FDG-PET positivity within colonic villous adenomas. A pathology database search was performed to identify all patients diagnosed with colonic villous adenoma between June 1, 1996 and December 1, 2000. Patients with a pathologic diagnosis of colonic villous adenoma and who also had a FDG-PET study up to 1 month before colonoscopy were included in this study. FDG-PET findings were compared with pathological features. Of more than 4,000 patients, six patients were diagnosed with colonic adenoma on subsequent colonoscopy following FDG-PET study. Based on the pathological findings, these 6 patients had a total of 2 villous and 9 tubulovillous adenomas. Five of the 6 patients showed foci of increased FDG uptake in the region of the colon that corresponded to the villous adenoma(s) detected on colonoscopy, which accounted for a true-positive rate of 83.3% (5/6 subjects). Focal lesions in the colon seen on FDG-PET examinations need to be investigated further, even though some of these will prove to be villous adenomas rather than colorectal carcinomas. Future studies in a larger number of patients are needed to evaluate the relationship of histopathological features of colonic polyps and detectability of these lesions by FDG-PET.

Adenoma, Villous↗
PubMed2005

Oncologic PET/CT: current status and controversies.

The introduction of integrated PET/CT has dramatically increased the worldwide rate of growth for PET, predominantly for oncologic imaging with the glucose analog 18F-fluorodeoxyglucose (FDG). A rapidly expanding body of literature demonstrates that the use of FDG-PET/CT and the resultant ability to interpret coregistered and fused PET and CT images lead to improved observer confidence and improved diagnostic performance by comparison with PET alone, CT alone, and visually correlated PET and CT. The value of PET/CT is likely to be even greater with new PET radiopharmaceuticals under development, many of which produce PET images with even fewer anatomical landmarks than FDG images. PET/CT is also likely to lead to the resurrection of 18F-fluoride as a principal agent for radionuclide bone imaging. There are a number of controversies related to PET/CT, including minimum training and experience requirements for interpreting physicians and defining new models for technical and professional reimbursement.

Clinical Competence↗
PubMed2005

Correlation of severity of FDG-PET hypometabolism and interictal regional delta slowing in temporal lobe epilepsy.

PURPOSE: We investigated the association of severity of hypometabolism detected by positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) and persistence of interictal EEG focal slowing in patients with refractory temporal lobe epilepsy. METHODS: Eighty temporal lobes of 40 consecutive patients with intractable temporal lobe epilepsy (mean age, 43.5 years) were studied. All patients underwent video-EEG monitoring, magnetic resonance imaging (MRI), and FDG-PET. Patients with either normal MRI or with unilateral mesial temporal sclerosis, but no other structural abnormality, were included. Interictal EEG delta slowing was graded as none, infrequent (one episode or less/hour), intermediate (more than one episode/hour), or continuous. PET hypometabolism was graded as none, mild, moderate, or severe. RESULTS: The severity of temporal lobe hypometabolism with PET was significantly correlated with the amount of delta activity in the interictal EEG, independent of MRI findings (Spearman r = 0.46; p < 0.0005). CONCLUSIONS: This observation suggests related underlying pathophysiologic mechanisms for metabolic and electrical dysfunction in temporal lobe epilepsy.

Adult↗
PubMed2005

Advances in positron emission tomographic imaging of lung cancer.

Positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) has been established as a useful tool in the management of patients with non-small cell lung cancer and promises to be as valuable in the clinical management of other cancers. PET imaging with FDG allows the assessment of tumor glucose metabolism in vivo; however, a number of other PET tracers are being used in oncologic research to assess changes in other cellular processes associated with malignant transformation of the cell. [11C]-Labeled methionine and choline are being used to assess changes in cell membrane synthesis; however, small studies have not shown the added information from these tracers to be clinically useful. DNA synthesis can be assessed by measuring the uptake of the thymidine analog 3'-deoxy-3'-[18F]fluorothymidine, which may be more specific for evaluating malignancy without the problem of false-positive results from inflammatory lesions, as seen with FDG. Tumor hypoxia imaging with copper-labeled diacetyl-bis(N(4)-methylthiosemicarbazone) or [18F]fluoromisonidazole may provide a better method of predicting which tumors will respond best to conventional therapy. The role of PET will continue to evolve with further clinical studies using these and other new tracers.

Carbon Radioisotopes↗
PubMed2004

Positron emission tomography in limited-stage small-cell lung cancer: a prospective study.

PURPOSE: To determine how often positron emission tomography with [(18)F]fluoro-2-deoxy-D-glucose (FDG-PET) detects extensive-stage small-cell lung cancer (SCLC) in patients considered to have limited-stage disease based on conventional staging procedures, and to determine the impact of PET on treatment planning for presumed limited-stage SCLC. PATIENTS AND METHODS: We prospectively performed pretreatment FDG-PET on 24 patients determined by conventional staging methods to have limited-stage SCLC (defined as disease that could be encompassed within a reasonable radiotherapy portal, excluding bilateral supraclavicular disease). PET images were evaluated for evidence of extensive-stage disease. Tumor-node-metastasis system staging was also assigned for each patient, with and without PET information. RESULTS: FDG-PET demonstrated findings consistent with extensive-stage SCLC in three of 24 patients. FDG-PET correctly upstaged two (8.3%) of 24 patients to extensive-stage disease (95% CI, 1.03% to 27.0%). PET correctly identified tumor in each SCLC mass (primary or nodal) that was suspected on computed tomography (CT) imaging, thus giving a lesion-based sensitivity relative to CT of 100%. PET identified unsuspected regional nodal metastasis in six (25%) of 24 patients, and the radiation therapy plan was significantly altered to include the PET-positive/CT-negative nodes within the high-dose region in each of these patients. Brain PET images in 23 patients disclosed no evidence of brain metastasis. CONCLUSION: FDG-PET has high sensitivity for SCLC and appears to be of value for initial staging and treatment planning of patients with presumed limited-stage disease.

Adult↗
PubMed2004

Lymph node control in cervical cancer.

PURPOSE: The aim was to evaluate pretreatment lymph node size, irradiation dose, and failure patterns. METHODS: Pretreatment PET and CT were performed in 208 patients. Lymph nodes were scored as either positive or negative by PET and lymph node size was measured by CT. Lymph node irradiation dose and sites of failure were recorded. RESULTS: The mean pelvic lymph node doses were: PET negative nodes, < or =1 cm, 66.8 Gy, and 0/76 failures; PET positive nodes, < or =1 cm, 66.8 Gy, and 3/89 failures; 1.1-< or =2 cm, 66.9 Gy, and 0/21 failures; 2.1-< or =3 cm, 69.4 Gy, and 2/15 failures; and 3.1 to < or =4 cm, 74.1 Gy, and 0/5 failures. The mean paraaortic lymph node dose was 43.3 Gy and there were no paraaortic failures for 24 patients with PET positive < or =1 cm nodes, 0/5 failures for 1.1 to < or =2 cm, and 0/4 failures for 2.1 to < or =3 cm. The most common site of failure was distant metastases. CONCLUSIONS: The irradiation doses given in this study were adequate to control most lymph node metastases. Positive lymph nodes of any size at diagnosis were the most significant predictor for developing distant metastases.

Adult↗
PubMed2004

Posttherapy [18F] fluorodeoxyglucose positron emission tomography in carcinoma of the cervix: response and outcome.

PURPOSE: The aim of this study was to evaluate response to therapy using posttherapy molecular imaging with [(18)F] fluorodeoxyglucose (FDG), and to compare the response with patient outcome. PATIENTS AND METHODS: This was a retrospective medical record review of 152 patients with carcinoma of the cervix. All patients underwent a pre- and posttreatment whole-body positron emission tomography (PET) imaging scan with FDG. Patients were treated with external irradiation and intracavitary brachytherapy, and most received concurrent weekly cisplatin. Posttherapy whole-body FDG-PET was performed 1 to 12 months (mean, 3 months) after completion of treatment. RESULTS: The posttherapy PET did not show any abnormal FDG uptake in 114 patients, and their 5-year cause-specific survival estimate was 80%. There was persistent (in the irradiated region) abnormal FDG uptake in the cervix or lymph nodes in 20 patients. Their 5-year cause-specific survival estimate was 32%. New anatomic sites (in unirradiated regions) of abnormal FDG uptake were present in 18 patients, and none were alive at 5 years. A Cox proportional hazards model of survival outcome indicated that any abnormal posttherapy FDG uptake (persistent or new) was the most significant prognostic factor for developing metastatic disease and death from cervical cancer when compared with pretreatment- and treatment-related prognostic factors (P <.0001). CONCLUSION: Posttherapy abnormal FDG uptake (persistent or new) as detected by whole-body PET measures tumor response and might be predictive of tumor recurrence and death from cervical cancer. Prospective validation of these results is warranted.

Female↗
PubMed2004

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.

Carcinoma, Non-Small-Cell Lung↗
PubMed2004

Treatment planning guidelines regarding the use of CT/PET-guided IMRT for cervical carcinoma with positive paraaortic lymph nodes.

PURPOSE: Computed tomography (CT)/positron emission tomography (PET)-guided intensity-modulated radiotherapy of the paraaortic lymph nodes (PALNs) has been proposed for patients with cervical carcinoma and paraaortic metastasis. This investigation attempted to determine the guidelines regarding the selection of appropriate treatment parameters (e.g., number of beams, beam geometry) and organ-specific parameters (e.g., importance weighting and tolerance dose) for intensity-modulated radiotherapy planning for the PALNs. METHODS AND MATERIALS: Patients underwent imaging using CT and PET. The images were registered, and the structures were contoured. A goal dose of 50.4 Gy and 59.4 Gy was assigned to the clinical target volume (lymph node bed) and gross tumor volume (PET-delineated PALNs), respectively. For each patient, multiple treatment plans using various beam geometries and planning parameters were executed and evaluated in terms of the dose-volume histograms of the target and critical structures. RESULTS: Acceptable sparing of the stomach, liver, and colon was achieved, regardless of the number of beams used. Sparing of the spinal cord was strongly dependent on the number and arrangement of the beams. Varying the number and arrangement of the beams affected small intestine sparing, but the amount of sparing was limited because the small intestine overlapped the target volumes, and, therefore, received the prescription dose. Adjusting the number of beams, beam angles, and prescription parameters provided minimal improvement in kidney sparing. CONCLUSION: We successfully developed treatment plans that deliver 59.4 Gy to the positive PALNs and 50.4 Gy to the paraaortic region using CT/PET-guided intensity-modulated radiotherapy.

Female↗