Positron Emission Tomography And Computed Tomography Research Articles

Standardized Uptake Values of Normal Organs on 18F-Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography Imaging

Standardized uptake values (SUVs) of normal organs were evaluated by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET-CT) scanning. Seventy patients (38 men and 32 women) with no non-physiological 18F-FDG uptake participated in the study. All patients fasted for at least 4 h before PET-CT imaging and their fasting blood glucose levels were within the normal range. Image acquisition was performed after intravenous administration of 18F-FDG and images were obtained from the vertex to the upper thigh region. The SUVs of various organs were determined from the transverse views. The uptake of 18F-FDG was highest in the cerebrum, cerebellum, myocardium, tonsils, liver and spleen in both sexes. Having knowledge of the physiological uptake of 18F-FDG and normal organ SUVs is required for the correct interpretation of whole-body 18F-FDG-PET-CT studies.

Impact of Integrated PET/CT on Variability of Target Volume Delineation in Rectal Cancer

Several studies have demonstrated substantial variability among individual radiation oncologists in defining target volumes using computed tomography (CT). The objective of this study was to determine the impact of combined positron emission tomography and computed tomography (PET/CT) on inter-observer variability of target volume delineation in rectal cancer. We also compared the relative concordance of two PET imaging tracers, 18F-fluorodeoxyglucose (FDG) and 18F-fluorodeoxythymidine (FLT), against conventional computed tomography (CT). Six consecutive patients with locally advanced rectal cancer were enrolled onto an institutional protocol involving preoperative chemoradiotherapy and correlative studies including FDG- and FLT-PET scans acquired in the treatment position. Using these image data sets, four radiation oncologists independently delineated primary and nodal gross tumor volumes (GTVp and GTVn) for a hypothetical boost treatment. Contours were first defined based on CT alone with observers blinded to the PET images, then based on combined PET/CT. An inter-observer similarity index (SI), ranging from a value of 0 for complete disagreement to 1 for complete agreement of contoured voxels, was calculated for each set of volumes. For primary gross tumor volume (GTVp), the difference in estimated SI between CT and FDG was modest (CT SI = 0.77 vs. FDG SI = 0.81), but statistically significant (p = 0.013). The SI difference between CT and FLT for GTVp was also slight (FLT SI = 0.80) and marginally non-significant (p < 0.082). For nodal gross tumor volume, (GTVn), SI was significantly lower for CT based volumes with an estimated SI of 0.22 compared to an estimated SI of 0.70 for FDG-PET/CT (p < 0.0001) and an estimated SI of 0.70 for FLT-PET/CT (p < 0.0001). Boost target volumes in rectal cancer based on combined PET/CT results in lower inter-observer variability compared with CT alone, particularly for nodal disease. The use of FDG and FLT did not appear to be different from this perspective.

The Advantage of PET and CT Integration in Examination of Lung Tumors

Purpose. To evaluate the diagnosis value of integrated positron emission tomography and computed tomography (PET/CT) with lung masses, this study emphasized the correlation between tumor size and maximum standardized uptake value (SUVmax) in selected regions of interest (ROI) of lung masses. Material and Methods. A retrospective analysis was performed on 85 patients with solid pulmonary lesions, all verified by pathology. The morphology, edge (speculated margins and lobule), size, density of pulmonary masses, and on-chest CT images were reviewed. The SUVmax in ROI of pulmonary masses was calculated. Results. Among the 85 patients with lung masses, 59 patients presented with pulmonary malignant neoplasm and 26 patients with benign lesions. The sensitivity, specificity, and accuracy were 89.8%, 61.5%, 81.2%, respectively, for PET measurement only, 88.1%, 65.4%, 81.2% for CT only, and 96.6%, 80.8%, 91.8% for PET/CT. The size of pulmonary malignant neoplasm in the 59 patients was apparently correlated with the ROI's SUVmax (, ). However, the size of pulmonary benign mass in the 26 patients was not correlated with the SUVmax. Conclusion. PET/CT is of greater value in characterization of lung masses than PET and CT performed separately. The examination of lung tumor can be further specified by the correlation between the size of pulmonary malignant neoplasm and the ROI's SUVmax.

Present role and future prospects of positron emission tomography in clinical oncology

Positron emission tomography (PET) has emerged as a significant molecular imaging technique in clinical oncology and cancer research. PET with (18)F-fluorodeoxyglucose ((18)F-FDG) demonstrates elevated glucose consumption by tumor cells, and is used clinically for the accurate staging and restaging of cancer, planning of radiotherapy, and predicting response or lack of response in the early stages of treatment. Combined PET and computed tomography (PET-CT) provides both functional and morphological information of the disease to allow accurate diagnosis of cancer. PET with new radiotracers such as protein synthesis markers and proliferation markers, as well as hypoxia and receptor-binding agents, will offer patient-specific images in order to yield tailored diagnostic and prognostic information.

187 Is imaging with co-registered positron emission tomography and computed tomography (PET-CT) superior to computed tomography (CT) alone for determining the gross tumour volume (GTV) and clinical target volume (CTV) in radical conformal radiotherapy for non-small cell lung cancer (NSCLC)?

187 Is imaging with co-registered positron emission tomography and computed tomography (PET-CT) superior to computed tomography (CT) alone for determining the gross tumour volume (GTV) and clinical target volume (CTV) in radical conformal radiotherapy for non-small cell lung cancer (NSCLC)?

Integrating A Focus on Overweight and Obesity in Clinical Practice: Practical Suggestions

**284** ### **Objectives** Aim of our study was to evaluate the usefulness of integrated positron emission tomography and computed tomography (PET/CT) in follow up of post operative colorectal cancer patients with raising CEA levels. ### **Methods** Thirty one histopathologically proven patients of post operative colorectal cancer were subjected to F-18 FDG PET/CT imaging. Base of skull to mid thigh imaging was performed in all patients. These patients were grouped into five categories depending upon CEA level. ### **Results** Of the total of 31 patients, CT alone demonstrated recurrence in 13(42%) patients, while PET/CT was positive in 22(71%) patients. In Group I (CEA \<5ng/ml) CT was positive in 1/5 patients and PET/CT was positive in 3/5 patients. In Group II (CEA 5-10ng/ml) CT was positive in 2/6 patients and PET/CT was positive in 4/6 patients. In Group III (CEA 10-20ng/ml) CT was positive in4/7 patients and PET/CT was positive in 5/7 patients. In Group IV (CEA 20-50ng/ml) CT was positive in 3/6 patients and PET/CT was positive in 5/6 patients. In Group V (CEA \>50ng/ml) CT was positive in 4/7 patients and PET/CT was positive in 7/7 patients. Among 13 patients in whom both CT and PET/CT were positive PET/CT demonstrated extra lesions in 10 (77%) patients and changed the management in 7 (54%) patients. Of the total of 31 patients PET/CT changed the management in 16(52%) patients. ### **Conclusions** This study demonstrates overall sensitivity of 71% for PET/CT compared to 42% for CT. PET/CT changes the management in half of the patients, highlighting the superior role of FDG PET/CT scan over CT scan

Integrated 18F-fluorodeoxyglucose positron emission tomography and computerized tomography in endodermal sinus tumor

Application of an in-line positron emission tomography and computerized tomography (PET-CT) in endodermal sinus tumor (EST) is described in this study. CASE 1: A young female with massive ascites postovarian mass resection had elevated alpha-fetoprotein (AFP) serum levels. Following a positive PET-CT study with increased (18)F-fluorodeoxyglucose (FDG) uptake, a CT-guided core biopsy of a peritoneal mass was performed. EST was diagnosed histologically. The patient was disease free after chemotherapy. Follow-up PET-CT was negative in keeping with no viable tumor tissue. CASE 2: A large pelvic mass diagnosed histologically as primarily EST was removed in a teenage patient with elevated AFP levels. PET-CT showed diffuse abdominal spread of FDG uptake, suggesting extensive peritoneal seeding. The patient was disease free after chemotherapy. Follow-up PET-CT was negative. EST is an FDG-avid tumor. PET-CT delineated the prechemotherapy tumor extent adequately ruled out the presence of residual tumor after a successful treatment.

Staging Accuracy in Mycosis Fungoides and Sézary Syndrome Using Integrated Positron Emission Tomography and Computed Tomography

To evaluate the usefulness of integrated positron emission tomography and computed tomography (PET/CT) in staging mycosis fungoides (MF) and Sézary syndrome and to correlate PET/CT data with histopathologic diagnosis of lymph nodes (LNs). A single-center, prospective cohort analysis. Academic referral center for cutaneous lymphoma. Thirteen patients with MF and SS at risk for secondary LN involvement. Interventions Patients were clinically evaluated based on general physical examination, total body skin examination, and laboratory screening. They underwent integrated PET/CT followed by excisional biopsy of LNs. We used PET/CT to assess LN size and metabolic activity. Enlarged LNs were defined as axillary or inguinal LNs with a short axis 1.5 cm or larger; or cervical LN, with a short axis 1.0 cm or larger. We classified LN pathologic results according to National Cancer Institute (LN1-4) and World Health Organization (WHO 1-3) criteria. We quantified PET activity using standardized uptake value (SUV) and correlated with LN grade. Based on CT size criteria alone, only 5 patients had enlarged LNs, whereas PET revealed hypermetabolic LNs in all 13 patients. Six patients had LN1-3, and 7 had effacement of LN architecture by lymphoma cells (LN4). Of the 7 patients with LN4 nodes, 4 had SS, and 3 had tumorous MF. Two patients with LN4 nodes had inguinal LNs smaller than 1.5 cm and would have been assigned an N0 classification without the use of integrated PET/CT. Correlation of SUV with LN grade revealed that LN1-3 nodes were associated with a mean SUV of 2.7 (median SUV, 2.2; range, 2.0-4.7) and LN4 nodes were associated with a mean SUV of 5.4 (median SUV, 3.9; range, 2.1-11.8). Patients with large cell transformation had the highest SUVs. For staging MF and SS, PET/CT was more sensitive in detecting LN involved by lymphoma compared with CT data alone and thus may provide more accurate staging and prognostic information. The intensity of PET activity correlated with histologic LN grade.

The Role of Positron Emission Tomography and Computed Tomography Fusion in the Management of Early-Stage and Advanced-Stage Primary Head and Neck Squamous Cell Carcinoma

To evaluate the role of positron emission tomography and computed tomography (PET-CT) fusion in the management of early-stage and advanced-stage primary head and neck squamous cell cancer. Retrospective analysis, with a blinded evaluation of clinical data and formation of a treatment plan. Single tertiary academic medical institution. Patients Thirty-six patients with previously untreated head and neck squamous cell carcinoma who underwent staging CT or magnetic resonance imaging of the neck prior to undergoing PET-CT as part of their initial diagnostic evaluation between July 2000 and January 2005. Confirmation or alteration of the treatment plan with the addition of the PET-CT information compared with traditional clinical and radiological data alone for early-stage and advanced-stage disease. When available, histopathological results were correlated with the PET-CT findings. Among the 36 patients, PET-CT provided additional information that confirmed the treatment plan in 25 patients (69%) and altered the treatment plan in 11 patients (31%). Six of 11 patients in the altered-treatment group had their tumors upstaged. Four of 8 patients with early-stage tumors had their treatment plan altered, compared with 7 of 28 patients with advanced-stage disease. Among 18 patients who underwent a surgical intervention for their primary tumor, PET-CT identified the primary tumor in all 18 patients and, based on histopathological findings, correctly staged the regional nodal disease in 9 of 16 patients who had their nodal disease addressed. The use of PET-CT is important in the initial treatment planning of early-stage and advanced-stage head and neck squamous cell carcinoma.

Diagnostic and Prognostic Value of 18-Fluorodeoxyglucose Positron Emission Tomography in Adrenocortical Carcinoma: A Prospective Comparison with Computed Tomography

Patients with adrenocortical cancer are submitted to multiple imaging procedures for diagnosis of recurrence and staging. The aim of this prospective study was to evaluate the diagnostic and prognostic values of fluorodeoxyglucose (FDG) using a combined positron emission tomography and computed tomography (PET/CT) modality, compared with thoracoabdominopelvic computed tomography (TAP-CT). Twenty-eight consecutive patients with adrenocortical cancer referred from November 2003 to December 2004 to the Institut Gustave Roussy were included. Mean time between PET/CT and TAP-CT was 16 d. Independent readers analyzed images of each modality. The gold standard was progression on follow-up TAP-CT or pathology. A total of 269 lesions in 57 organs were depicted in 22 patients. The sensitivities for the detection of distinct lesions and the diagnosis of metastatic organs were 90 and 93% for PET/CT and 88 and 82% for TAP-CT, respectively. Twelve percent of the lesions were seen on PET/CT only and 10% on TAP-CT only. Eighteen percent of the metastatic organs were diagnosed with PET/CT only and 7% with TAP-CT only. Thirty-eight percent of the local relapses were seen only with PET/CT. PET/CT depicted three false-positive lesions. Treatment modalities were modified by PET/CT findings in five cases among which one was falsely positive. Tumor size and mitotic rate were significantly associated with FDG uptake. The intensity of FDG uptake (maximum standardized uptake value > 10) and the volume of FDG uptake (>150 ml) were significant prognostic factors for survival. We show that FDG-PET/CT is complementary to TAP-CT and of special interest in the diagnosis of local relapses.

False-Positive FDG PET Uptake−the Role of PET/CT

Positron emission tomography (PET) is a powerful molecular imaging technique for the human body-imaging applications currently available. As altered glucose metabolism is characteristic for many malignancies, FDG-PET is mostly used in oncology for staging and therapy control. Although PET is a sensitive tool for detecting malignancy, FDG uptake is not tumor specific. It can also be seen in healthy tissue or in benign disease as inflammation or posttraumatic repair and could be mistaken for cancer. The experienced nuclear medicine physician mostly manages to differentiate malignant from non-malignant FDG uptake, but some findings may remain ambiguous. In these cases, the difficulties in differentiating physiologic variants or benign causes of FDG uptake from tumor tissue can often be overcome by combined PET and CT (PET/CT) as anatomic information is added to the metabolic data. Thus, PET/CT improves the diagnostic accuracy compared to PET alone and helps to avoid unnecessary surgery/therapy. However, PET/CT involves other sources of artifacts that may occur when using CT for attenuation correction of PET or by patient motion caused by respiration or bowel movements.

Diagnostic Utility of Positron Emission Tomography‐Computed Tomography for Predicting Malignancy in Cystic Neck Masses in Adults

Combined positron emission tomography and computed tomography (PET-CT) is used for the diagnostic evaluation and staging of squamous cell carcinoma of the head and neck (SCCHN). By superimposing anatomic localization of CT with the physiologic data of PET, occult primary and metastatic neoplasms might be identified. Because the diagnostic algorithm for cystic neck masses in adults often overlaps with the work-up of cancer of unknown primary site, we evaluated the utility of PET-CT scans to identify the presence of malignancy and the location of primary tumor. Single-institution retrospective case review series. We reviewed the PET-CT imaging of cystic neck masses occurring in five patients over 40 years of age with significant risk factors for SCCHN and correlated this information with histopathology. In each patient in our series, the PET portion of a combined PET-CT was misleading, whereas the CT examination was more suggestive of the correct pathology. Ultimately, clinical judgment and endoscopic evaluation, guided by CT findings, were most valuable for distinguishing malignant versus benign processes and identifying the primary tumor sites. PET-CT may not be a reliable modality for identifying malignancy in adults with suspicious cystic neck masses. A thorough clinical evaluation by an experienced head and neck surgeon, in conjunction with contrast-enhanced CT, may be sufficient to facilitate the optimal management of such patients.

Improved Detection of Second Primary Cancer Using Integrated [18F] Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography for Initial Tumor Staging

This study evaluated prospectively the value of integrated whole-body positron emission tomography and computed tomography (PET/CT) using [18F] fluorodeoxyglucose (FDG) in detecting a second primary cancer at the time of the initial staging in comparison with a conventional staging work-up (CSW). The participants were 547 patients diagnosed with cancer who underwent FDG PET/CT imaging for the initial staging. An additional diagnostic evaluation was performed when there were abnormal findings indicative of a second primary cancer on either PET/CT or CSW considering the site and the biologic behavior of the alleged primary tumor. A total of 27 second primary malignant tumors were identified in 26 of the 547 patients (4.8%). FDG PET/CT found 45 lesions indicative of a second primary cancer, of which 24 lesions were proved to be a second primary cancer, seven were clinically unexpected metastases, and 14 lesions were benign. Therefore, sensitivity and positive predictive value of FDG PET/CT in detecting a second primary cancer or an unexpected metastasis were 91% (31 of 34) and 69% (31 of 45), respectively. In contrast, CSW could not identify 16 second primary cancers and one metastatic lesion. FDG PET/CT at the time of the initial staging is useful for screening a second primary cancer with a high sensitivity. An additional diagnostic work-up is essential when abnormal findings, which are indicative of a second primary cancer, are obtained on PET/CT images to rule out the presence of either a second primary cancer or an unexpected metastasis.

Etiology of Solitary Extrapulmonary Positron Emission Tomography and Computed Tomography Findings in Patients With Lung Cancer

The aim of this prospective study was to assess the incidence and the nature of solitary extrapulmonary [18F] fluorodeoxyglucose (FDG) accumulations in patients with non-small-cell lung cancer (NSCLC) staged with integrated positron emission tomography and computed tomography (PET/CT) and to evaluate the impact on management. A total of 350 patients with NSCLC underwent whole-body PET/CT imaging. All solitary extrapulmonary FDG accumulations were evaluated by histopathology, further imaging, or clinical follow-up. PET/CT imaging revealed extrapulmonary lesions in 110 patients. In 72 patients (21%), solitary lesions were present. A diagnosis was obtained in 69 of these patients, including 37 (54%) with solitary metastases and 32 (46%) with lesions unrelated to the lung primary. Histopathologic examinations of these 32 lesions revealed a second clinically unsuspected malignancy or a recurrence of a previous diagnosed carcinoma in six patients (19%) and a benign tumor or inflammatory lesion in 26 patients (81%). The six malignancies consisted of carcinoma of the breast in two patients, and carcinoma of the orbit, esophagus, prostate, and non-Hodgkin's lymphoma in one patient each. Benign tumors and inflammatory lesions included eight colon adenomas, four Warthin's tumors, one granuloma of the lower jaw, one adenoma of the thyroid gland, one compensatory muscle activity due to vocal chord palsy, two occurrences of arthritis, three occurrences of reflux esophagitis, two occurrences of pancreatitis, two occurrences of diverticulitis, one hemorrhoidal inflammation, and one rib fracture. Solitary extrapulmonary FDG accumulations in patients with newly diagnosed lung cancer should be analyzed critically for correct staging and optimal therapy, given that up to half of the lesions may represent unrelated malignancies or benign disease.

The use of Combined PET/CT for Localizing Recurrent Head and Neck Cancer: The Pittsburgh Experience

We performed a retrospective study of 47 patients to ascertain the ability of combined positron-emission tomography and computed tomography (PET/CT) to localize recurrent head and neck cancer. When clinically warranted, biopsies were performed in an attempt to obtain pathologic confirmation of the PET/CT findings. Of the 47 patients, 33 exhibited PET/CT findings consistent with recurrent cancer. Of the 33 patients, 25 underwent either biopsy or surgical excision of disease in an attempt to obtain a pathologic confirmation. Biopsy analysis confirmed the PET/CT findings in 22 of these patients; in the remaining 3 patients, pathologic findings were inconsistent with the PET/CT diagnosis. Based on the subset of 25 patients who underwent pathologic testing, the sensitivity of combined PET/CT was 95% and the specificity was 60%. We conclude that combined PET/CT imaging is a valuable tool for localizing tumor recurrence in patients with head and neck cancer.

Combined positron emission tomography and computed tomography for the detection of recurrent ovarian mucinous adenocarcinoma

Background The role of combined positron emission tomography and computed tomography (PET-CT) in the diagnosis of recurrent ovarian mucinous adenocarcinoma is uncertain because of previous reports that PET has limited sensitivity in the detection of mucinous neoplasms. Case A 71-year-old white woman presented with complaints of right lower quadrant pain and a palpable adnexal mass. Physical examination and transvaginal ultrasonography revealed a 12 × 13 cm cystic mass in the left side of the pelvis. Exploratory laparotomy, optimal tumor-reductive surgery, total abdominal hysterectomy, bilateral salpingo-oophorectomy, appendectomy, and omentectomy were performed. The diagnosis was FIGO stage IIIC well-differentiated ovarian mucinous adenocarcinoma. The patient was treated with 6 cycles of carboplatin and paclitaxel. Four months after completing chemotherapy, the patient was noted to have an elevated serum CA125 level (72 U/mL), being otherwise asymptomatic. Findings on abdominal and pelvic CT were compatible with postsurgical changes. PET-CT was performed and revealed increased metabolism along the posterior aspect of the right rectus abdominis muscle and abutting the anterior wall of an adjacent loop of bowel. Conclusion PET-CT may identify clinically occult recurrent ovarian mucinous adenocarcinoma.

Marked Improvement in Staging Accuracy in Mycosis Fungoides/Sézary Syndrome Using Integrated Positron Emission Tomography and Computed Tomography (PET/CT).

Staging of mycosis fungoides/Sézary syndrome (MF/SS), the most common cutaneous T cell lymphoma (CTCL), is primarily based on the type and extent of skin involvement and the presence or absence of extracutaneous disease. In patients with large cell transformation, tumors, erythroderma, or abnormal lymph nodes on physical exam, staging includes CT scan to look for visceral or lymph node (LN) disease followed by biopsy of enlarged LN. Integrated PET/CT combines anatomic data from CT with functional data from PET and has been useful in the staging of many non-Hodgkin's lymphomas. To date, however, its role in staging MF/SS has not been investigated. We assessed the utility of integrated PET/CT in staging thirteen patients with MF (T2=1,T3=4,T4=1) or SS (T4B2=7) at high-risk for LN disease. Based on anatomic data from the CT component alone, only five of thirteen had enlarged LN (axillary/inguinal LN short axis ≥1.5cm or cervical LN short axis ≥1.0cm) and would have been referred for biopsy. In comparison, PET showed that all thirteen patients had hypermetabolic activity in at least one LN region. All patients had excisional LN biopsy and the extent of LN involvement was classified according to NCI criteria (LN1-4 classification). Six patients had LN1-3 and seven had effacement of LN architecture by lymphoma cells (LN4). Of the seven LN4 patients, four had SS and three had tumor MF. PET/CT helped identify the most suspicious LN region for biopsy, which led to the accurate stage of IVA. Notably, two patients had LN smaller than the CT size criteria and would have been incorrectly staged without the use of integrated PET/CT. Furthermore, we quantified the intensity of PET activity using standardized uptake value (SUV) and correlated this with LN grade. Patients with LN1-3 had a mean SUV of 2.7, median 2.2 (2.0–4.7) and patients with LN4 had a mean SUV of 5.4, median 3.9 (2.1– 11.8); p value 0.08. Ongoing analysis of additional patients may further define whether PET/CT can be used to significantly differentiate between LN1-3 vs LN4. Thus, for staging MF/SS, integrated PET/CT was more sensitive and specific in detecting malignant LN compared to CT alone and consequently provided more accurate staging and prognostic information. A larger scale study would be essential to confirm the superior staging capability of PET/CT over CT alone in MF/SS.Summary of PET/CT correlation with LN pathology results in MF/SSPatientT classMax SUVLN size (SA,cm)LN regionNCI gradeWHO gradeFinal stage1T32.01.2AxillaryLN11IIB2T42.11.3AxillaryLN11IIIB3T22.21.0InguinalLN21IIA4T44.71.0AxillaryLN21IIIB5T43.01.2InguinalLN21IIIB6T42.01.1InguinalLN32IIIB7T33.71.4CervicalLN43IVA8T43.21.5InguinalLN43IVA9T33.91.3InguinalLN43IVA10T411.83.2InguinalLN43IVA11T46.61.3InguinalLN43IVA12T46.32.1InguinalLN43IVA13T32.12.1AxillaryLN43IVAAbbreviations: T, tumor; SUV, standardized uptake value; LN, lymph node; SA, short axis; cm, centimeter

Laparoscopic resection of occult metastasis using the combination of FDG-positron emission tomography/computed tomography image fusion with intraoperative probe guidance in a woman with recurrent ovarian cancer

Background Positron emission tomography and computed tomography (PET/CT) have a potential role in detecting and locating recurrent ovarian cancer. Precise tumor location during surgical treatment is often difficult, owing to limited tumor size and post-surgical anatomic modifications. The surgical gamma probe, which has become increasing popular in recent years with the development of sentinel node mapping, may improve tumor detection and facilitate resection of occult metastases. Case report. We describe the first case of laparoscopic resection of occult metastasis using the combination of FDG-PET/CT image fusion with intraoperative FDG-sensitive probing in a patient with recurrent ovarian cancer. Conclusion. FDG-sensitive probe combined with preoperative PET/CT image fusion can help to detect occult metastasis and guide laparoscopic excision.

Diagnosis in medullary thyroid cancer with [18F]FDG-PET and improvement using a combined PET/CT scanner.

Today, positron emission tomography (PET) investigation using fluorodeoxyglucose (FDG) is the most sensitive and specific single modality established for localizing metastases of medullary thyroid cancer (MTC). Even at calcitonin serum levels below 20 pg/ml, tumour localization may be successful in individual cases. However, especially in such early tumour stages, the morphological correlation using PET is unsatisfactory. With the newly available fixed combination of PET and computed tomography (PET/CT), this drawback can be overcome as PET/CT allows a point-by-point correlation of pathological function with morphological structure. Conventional PET alone yielded an approx 80 % sensitivity and specificity in MTC: a result that will be surpassed by the combined PET/CT scanner.

Positron Emission Tomography/Computed Tomography Imaging for the Detection of Recurrent Ovarian and Fallopian Tube Carcinoma: A Retrospective Review

Purpose. Imaging modalities to evaluate ovarian/fallopian tube cancer patients for recurrence are limited. Positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound lack the sensitivity to consistently detect recurrence or measurable disease in these patients. A new technique combines PET and CT (PET/CT) images to identify increased metabolic activity and to locate that signal with improved anatomic specificity. The objective of this study is to compare PET/CT, CT, and histologic findings in patients with recurrent ovarian/fallopian tube cancers.Methods. Retrospective chart review of eight patients with primary ovarian (n = 6) or fallopian tube (n = 2) cancer was performed. All eight patients underwent initial cytoreductive surgery. Five patients initially received chemotherapy, one received radioactive phosphorus (32P), one received tamoxifen, and one received no therapy. Seven of eight patients had a suspected recurrence based on clinical examination, elevated CA-125 level, and/or abnormal CT findings; one patient requested a PET/CT. Histologic findings from surgery were correlated with PET/CT and CT findings.Results. All eight patients had positive histology, and of these, seven patients had a negative CT and five patients had lesions that were correctly identified by PET/CT.Conclusions. Five of the eight (62%) patients had recurrent disease based on correlative histology with a positive PET/CT and a negative CT. These preliminary findings suggest that combined PET/CT may be an effective means of identifying patients with recurrent ovarian/fallopian tube cancer. Such patients could potentially proceed to salvage treatment and avoid the morbidity and expense of surgical assessment. Pilot studies comparing CT, PET, PET/CT, and histologic findings are underway.