FDG PET and immunoscintigraphy with 99mTc-labeled antibody fragments for detection of the recurrence of colorectal carcinoma.

The aim of this study was to compare FDG PET with a new monoclonal antibody-based imaging agent that comprises an anti-carcinoembryonic antigen (CEA) monoclonal antibody Fab' fragment directly labeled with 99mTc. METHODS: Twenty-eight patients who were previously treated for colorectal carcinoma and in whom recurrence was suspected were examined with FDG PET and immunoscintigraphy. The most common indications were an elevation of serum CEA (13 patients), suggestive lesions documented by CT (9 patients), sonography (4 patients), and severe constipation (2 patients). Planar imaging and SPECT were performed 4-6 h after intravenous injection of the new imaging agent. Whole-body PET was performed 45-60 min after intravenous injection of FDG. The findings were confirmed by conventional diagnostic modalities, surgery, and histology. RESULTS: Histology confirmed local tumor recurrence in 9 of 28 patients. Clinical follow-up or CT confirmed the presence of liver metastases in 9 patients and lymph node involvement, lung metastases, and bone metastases in 2 patients each. The new agent correctly detected 8 of 9 local recurrences, whereas FDG PET was able to detect all 9 cases and in 1 case was false-positive. Liver metastases were confirmed in 9 patients by FDG PET but in only 1 patient by the new agent. Two cases with lymph node metastases and 2 cases with lung metastases were correctly identified by FDG PET, but none were detected by the new agent. Finally, bone metastases were identified in 1 patient by FDG PET but not with the new agent, whereas bone marrow infiltration (n = 1) was diagnosed by both imaging modalities. CONCLUSION: These results indicate that FDG PET and 99mTc-labeled anti-CEA Fab' are suitable for the diagnosis of local recurrence of colorectal carcinoma but that FDG PET is clearly superior in the detection of distant metastases (liver, bone, and lung) and lymph node involvement.     

18 F-FDG PET显像与99Tcm-MDP全身骨显像诊断肿瘤远处转移的比较

目的　评价18F 脱氧葡萄糖 (FDG)PET肿瘤显像与99Tcm 亚甲基二膦酸盐 (MDP)全身骨显像对检出骨和远处转移的价值。方法　对 16例恶性肿瘤放化疗后的患者进行18F FDGPET显像和99Tcm MDP全身骨显像 ,并对两种结果进行了比较。结果　 16例肿瘤患者中18F FDGPET显像皆阳性 ,其中 14例患者有远处转移 ,转移病灶共 62处 ,其中骨转移病灶 2 0处 ;在全身骨显像中 ,11例有局限性异常放射性浓聚 ,其中 2例为单一病灶 ,9例为多发病灶 ,共检出病灶 5 7处 ,另 5例骨显像正常。结论　18F FDGPET对恶性肿瘤的诊断具有较高的准确性和特异性 ,但对骨转移灶的诊断价值相对较差 ;99Tcm MDP显像阴性或单一病灶的可疑转移瘤患者有必要进行18F FDGPET检查 ,以明确诊断其他远处转移灶     

Whole-body MR imaging for detection of bone metastases in children and young adults: comparison with skeletal scintigraphy and FDG PET.

OBJECTIVE: The purpose of this study was to compare the diagnostic accuracy of whole-body MR imaging, skeletal scintigraphy, and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for the detection of bone metastases in children. SUBJECTS AND METHODS: Thirty-nine children and young adults who were 2--19 years old and who had Ewing's sarcoma, osteosarcoma, lymphoma, rhabdomyosarcoma, melanoma, and Langerhans' cell histiocytosis underwent whole-body spin-echo MR imaging, skeletal scintigraphy, and FDG PET for the initial staging of bone marrow metastases. The number and location of bone and bone marrow lesions diagnosed with each imaging modality were correlated with biopsy and clinical follow-up as the standard of reference. RESULTS: Twenty-one patients exhibited 51 bone metastases. Sensitivities for the detection of bone metastases were 90% for FDG PET, 82% for whole-body MR imaging, and 71% for skeletal scintigraphy; these data were significantly different (p < 0.05). False-negative lesions were different for the three imaging modalities, mainly depending on lesion location. Most false-positive lesions were diagnosed using FDG PET. CONCLUSION: Whole-body MR imaging has a higher sensitivity than skeletal scintigraphy for the detection of bone marrow metastases but a lower sensitivity than FDG PET.     

Screening for cerebral metastases with FDG PET in patients undergoing whole-body staging of non-central nervous system malignancy

PURPOSE: To compare fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) with the current standard, magnetic resonance (MR) imaging, to determine the sensitivity and specificity of FDG PET for detection of cerebral metastases and to determine the factors that may affect lesion conspicuity. MATERIALS AND METHODS: Forty patients underwent brain PET and contrast material-enhanced brain MR imaging, with a maximum of 30 days between examinations. PET and MR images were each retrospectively reviewed by two independent readers who were blinded to the clinical history and results of the other technique. Presence of metastatic disease was recorded for each modality. Sensitivity and specificity of FDG PET were determined with MR imaging as the standard. Statistical analysis was performed with the Fisher exact test and the logistic regression model. RESULTS: Sixteen patients had cerebral metastases at MR imaging, and in 12 of these, PET scans were interpreted as showing metastatic disease (in four, scans were false-negative). Twenty-four patients had no cerebral metastases at MR imaging, and 20 of these had PET scans interpreted as normal (in four, scans were false-positive). For identification of patients with cerebral metastases, FDG PET had a sensitivity of 75% (12 of 16) and a specificity of 83% (20 of 24). Thirty-eight metastatic lesions were seen at MR imaging; 23 (61%) of these were identified at PET. Size was a statistically significant factor that influenced lesion detection at PET (P <.001). CONCLUSION: Only 61% of metastatic lesions in the brain were identified at PET. In particular, detection of small lesions was difficult.     

Impact of FDG PET for staging of Ewing sarcomas and primitive neuroectodermal tumours

AIM: High-grade Ewing sarcomas and Primitive neuroectodermal tumours (PNET) make up the tumours of the Ewing family. Our purpose was to evaluate the value of [18F]fluorodeoxyglucose positron emission tomography (FDG PET) in patients with Ewing tumours. PATIENTS AND METHODS: Twenty-four patients who had PET because of a suspected Ewing tumour during a 5-year period were included in this retrospective study. The images of 33 whole-body FDG PET investigations performed in primary or secondary diagnostics were analysed visually and semi-quantitatively by using standardized uptake values (SUVs). In 14 cases, PET was compared to bone scintigraphy regarding bone lesions. The final diagnosis was based on histology, imaging and follow-up. RESULTS: Histologically, the primary lesions were 10 Ewing sarcoma, 13 PNET and one osteomyelitis. The sensitivity and specificity of an examination-based analysis (presence of Ewing tumour and/or its metastases) were 96 and 78%, respectively. Altogether, 163 focal lesions were evaluated. Sensitivity and specificity regarding individual lesions were 73 and 78%. This lower sensitivity is mainly due to small lesions. In true-positive cases, the mean SUV was 4.54+/-2.79, and the SUVs in two false-positive cases were 4.66 and 1.60. True-positive and false-positive cases could not be differentiated definitively based on SUVs because of overlap and low values in true-positive lesions. In four cases, PET depicted 70 while bone scintigraphy depicted only eight bone metastases. CONCLUSION: An FDG PET investigation is a valuable method in the case of Ewing tumours. PET is superior to bone scintigraphy in the detection of bone metastases of Ewing tumours. For the depiction of small lesions, mainly represented by pulmonary metastases, PET is less sensitive than helical computed tomography. Determination of the role of whole-body FDG PET in diagnostic algorithm needs further investigation.     

The value of fluorine-18 fluorodeoxyglucose PET in patients with medullary thyroid cancer

The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultrasonography, magnetic resonance imaging, computerized tomography and scintigraphy using pentavalent technetium-99m dimercaptosuccinic acid, thallium-201 chloride, indium-111 pentetreotide, anti-CEA antibodies or metaiodobenzylguanidine) must be performed consecutively in patients with elevated calcitonin levels until the tumour is localized. In this prospective study, we investigated the value of fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET) in the follow-up of patients with MTC. [18F]FDG PET examinations of the neck and the chest were performed in 20 patients with elevated calcitonin levels or sonographic abnormalities in the neck. Positive [18F]FDG findings were validated by histology, computerized tomography or selective venous catheterization. [18F]FDG PET detected tumour in 13/17 patients (nine cases were validated by histology, four by computerized tomography). Five patients showed completely negative PET scans (of these cases, one was true-negative and four false-negative). One patient with [18F]FDG accumulation in pulmonary lesions from silicosis and one patient with a neck lesion that was not subjected to histological validation had to be excluded. Considering all validated localizations, [18F]FDG PET detected 12/14 tumour manifestations in the neck, 6/7 mediastinal metastases, 2/2 pulmonary metastases and 2/2 bone metastases. In two patients with elevated calcitonin levels, no diagnostic modality was able to localize a tumour. The sensitivity of [18F]FDG PET in the follow-up of MTC was 76% (95% confidence interval 53%-94%); this is encouraging. [18F]FDG PET promises to be a valuable diagnostic method, especially for the detection of lymph node metastases, surgical resection of which can result in complete remission.     

Diagnostic accuracy of FDG PET imaging for the detection of recurrent or metastatic gynecologic cancer

PURPOSE: This study evaluated the diagnostic role and accuracy of positron emission tomography (PET) using 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) for the detection of tumor foci in patients with suspected recurrent or metastatic lesions of gynecologic cancers. MATERIALS AND METHODS: FDG PET imaging was performed on 51 patients with a previous history of gynecologic cancer who were referred for a clinical suspicion of recurrent disease. PET acquisition was started 50-60 min after the intravenous injection of 5-6 MBq/kg FDG in all patients. The PET images were interpreted visually, and tracer uptake was quantitated as the standardized uptake value adjusted to body weight (SUV) in the lesions showing FDG uptake. The accuracy of the PET results was assessed by a consensual verdict based on histology, cytology, other imaging and clinical follow-up. RESULTS: FDG PET correctly diagnosed 33 of 36 patients with recurrent disease and 12 of 15 patients without recurrence. On patient-based analysis, the sensitivity, specificity and accuracy of FDG PET were 91.7%, 80.0% and 88.2%, respectively, depending on the selected scheme for visual scoring of the lesions. The area index in receiver-operating characteristic analysis was 0.95 for patient detection. Malignant lesions accumulated significantly more FDG than the benign ones (the mean SUVs were 3.7 +/- 1.9 and 1.6 +/- 1.1, respectively, p = 0.004). The sensitivity and specificity in correct identification of tumor recurrence or metastases using a threshold SUV 1.9 were 88.8% and 66.7% in contrast to the visual analysis (sensitivity 96.4%, specificity 50%) on a lesion-based analysis. The partial volume effect of SUV in a few small lesions and the presence of bone lesions in which FDG uptake was relatively low might be the reason for the lower sensitivity in SUV analysis. FDG PET was valuable when CT/MRI was negative or inconclusive, and in patients with elevated tumor marker levels as well as with normal tumor marker levels when recurrence was suspected clinically. However, PET failed to visualize some small metastatic lesions in lung and bone, and showed falsely high FDG uptake in some benign lesions. CONCLUSION: The results indicated that FDG PET is a reliable and accurate diagnostic method for detecting recurrent or metastatic gynecologic cancer particularly lymph node metastases. Although the sensitivity of PET for detecting small metastases was relatively limited, the overall sensitivity of FDG PET was significantly higher than morphologic imaging.     

FDG PET in the diagnosis of hilar cholangiocarcinoma.

Resectional surgery offers a curative intent and a survival benefit for patients with hilar cholangiocarcinoma, but is associated with high morbidity. Since morphological imaging cannot solve differential diagnosis preoperatively, in order to exclude patients inappropriate to this aggressive surgery, we evaluated the impact of functional imaging using fluorodeoxyglucose positron emission tomography (FDG PET) in the detection of cholangiocarcinoma and its usefulness in the differentiation from benign Klatskin tumour-mimicking lesions. Fifteen consecutive patients aged 47-78 years underwent standardized whole-body FDG PET with attenuation correction before potentially curative surgery using a conventional full-ring PET scanner with an axial field-of-view of 16.2 cm. FDG PET was evaluated visually and semiquantitatively using tumour-to-background ratios (T/B) ratios. All lesions were evaluated histopathologically. FDG PET presumed to be indicative for carcinoma was positive in 12 of 15 patients, true positive in 10 (T/B ratio, 3.2+/-1.9) and false positive in two of them (T/B ratios, 2.1 and 2.8) with Klatskin tumour-mimicking lesions. While all true positive PET results were seen in the tubular type of cholangiocarcinoma with a high amount of tumour cells and only low production of mucus, a false negative FDG PET in three patients was observed in mucinous adenocarcinoma. Additionally, FDG PET detected locoregional lymph nodes in two patients and distant metastases in a further three patients. Due to false positive results FDG PET does not allow the differentiation of benign from malignant lesions, and FDG PET should be avoided in patients with mucinous cholangiocarcinoma. However, FDG PET may have significant influence on the treatment strategy in as much as 20% of the patients, since it may detect distant metastases.     

Positron emission tomography for evaluation of colorectal carcinoma

Evaluation of patients with known or suspected recurrent colorectal carcinoma is now an accepted indication for FDG PET imaging. FDG PET does not replace imaging modalities such as CT for preoperative anatomic evaluation but is indicated as the initial test for diagnosis and staging of recurrence and for preoperative staging (N and M) of known recurrence that is considered to be resectable. FDG PET imaging is valuable for differentiation of posttreatment changes from recurrent tumor, differentiation of benign from malignant lesions (indeterminate lymph nodes, hepatic and pulmonary lesions), and evaluation of patients with rising tumor markers in the absence of a known source. Addition of FDG PET to the evaluation of these patients reduces overall treatment costs by accurately identifying patients who will and will not benefit from surgical procedures. Although initial staging at the time of diagnosis is often performed during colectomy, FDG PET imaging is recommended for a subgroup of patients at high risk (with elevated CEA levels) and normal CT and for whom surgery can be avoided if FDG PET shows metastases. Screening for recurrence in patients at high risk has also been advocated. FDG PET imaging seems promising for monitoring therapy, but larger studies are necessary.     

Usefulness of intraoperative sonography for revealing hepatic metastases from colorectal cancer in patients selected for surgery after undergoing FDG PET.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of preoperative positron emission tomography (PET) with FDG and intraoperative sonography with the standard of histologic examination of resected liver specimens in evaluating patients for curative resection of liver metastases from colorectal cancer. MATERIALS AND METHODS: We retrospectively identified 47 patients with recurrent colorectal cancer who underwent surgical exploration for possible curative resection of hepatic metastases. All patients underwent CT or MR imaging and FDG PET preoperatively and intraoperative sonography. The performance of the imaging techniques was evaluated through review of the radiologic reports and correlation with surgical and histopathologic findings. RESULTS: Eighty-seven malignant hepatic lesions were identified by histopathologic analysis of liver specimens, and 23 benign hepatic abnormalities were documented histopathologically or by uroradiologic imaging. For hepatic sections characterized as containing metastases by radiologic imaging, the positive predictive value for FDG PET was 93% (54/58); for intraoperative sonography, 87% (52/60); and for conventional imaging, 83% (43/52). For individual lesions characterized as probably malignant, the positive predictive value for FDG PET was 93% (62/68); for intraoperative sonography, 89% (63/71); and for conventional imaging, 78% (46/59). The findings at intraoperative sonography led to a change in the clinical treatment of only one patient (2%). CONCLUSION: The results indicate that FDG PET effectively screens potential candidates for curative liver resection. Although intraoperative sonography helps to determine the anatomic location of metastases thus facilitating surgical resection, its adjunctive use in patients screened preoperatively by FDG PET has limited impact on treatment selection.     

The value of fluorine-18 fluorodeoxyglucose positron emission tomography in patients with medullary thyroid cancer

The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultrasonography, magnetic resonance imaging, computerized tomography and scintigraphy using pentavalent technetium-99m dimercaptosuccinic acid, thallium-201 chloride, indium-111 pentetreotide, anti-CEA antibodies or metaiodobenzylguanidine) must be performed consecutively in patients with elevated calcitonin levels until the tumour is localized. In this prospective study, we investigated the value of fluorine-18 fluorodeoxyglucose positron emission tomography ([¹⁸F]FDG PET) in the follow-up of patients with MTC. [¹⁸F]FDG PET examinations of the neck and the chest were performed in 20 patients with elevated calcitonin levels or sonographic abnormalities in the neck. Positive [¹⁸F]FDG findings were validated by histology, computerized tomography or selective venous catheterization. [¹⁸F]FDG PET detected tumour in 13/17 patients (nine cases were validated by histology, four by computerized tomography). Five patients showed completely negative PET scans (of these cases, one was true-negative and four false-negative). One patient with [¹⁸F]FDG accumulation in pulmonary lesions from silicosis and one patient with a neck lesion that was not subjected to histological validation had to be excluded. Considering all validated localizations, [¹⁸F]FDG PET detected 12/14 tumour manifestations in the neck, 6/7 mediastinal metastases, 2/2 pulmonary metastases and 2/2 bone metastases. In two patients with elevated calcitonin levels, no diagnostic modality was able to localize a tumour. The sensitivity of [¹⁸F]FDG PET in the follow-up of MTC was 76% (95% confidence interval 53%–94%); this is encouraging. [¹⁸F]FDG PET promises to be a valuable diagnostic method, especially for the detection of lymph node metastases, surgical resection of which can result in complete remission. Received 16 September 1999 and in revised form 19 January 2000     

Primary and metastatic breast carcinoma: initial clinical evaluation with PET with the radiolabeled glucose analogue 2-[F-18]-fluoro-2-deoxy-D-glucose

The authors assessed whether breast cancers can be detected by means of positron emission tomography (PET) with the positron-emitter-labeled glucose analogue 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG). In 12 patients with primary and/or metastatic breast cancer, PET images of F-18 distribution in vivo were obtained approximately 1 hour after intravenous injection of 10 mCi of FDG. Scan findings were correlated with other imaging data and physical examination and biopsy results. Ten of 10 primary breast cancers were imaged by means of FDG PET with a tumor:background FDG uptake ratio of 8.1 (median). Ten of 10 bone metastases were imaged with a tumor:normal bone uptake ratio of 6.05 (median). Five of five known soft-tissue metastases and four previously unsuspected nodal lesions were found with PET. No false-positive foci of FDG uptake were demonstrated. In two cases with negative mammograms due to dense breast parenchyma, FDG PET clearly delineated the primary tumors. These preliminary data demonstrate the feasibility and substantial potential of PET scanning with FDG to detect and localize both primary and metastatic breast cancers.     

PET/CT imaging of thyroid cancer

Positron emission tomography (PET) is a highly sensitive, low invasive technology for cancer biology imaging. The role of F-18 FDG PET/CT in differentiated thyroid cancer (DTC) is well established, particularly in patients presenting with elevated Tg levels and negative radioactive iodine WBS. It has been demonstrated that F-18 FDG uptake represents less differentiated thyroid cancer cells or dedifferentiated cells and PET positive lesions are more likely to be resistant to I treatment. The uptake of F-18 FDG is related to tumor size, thyroid capsule invasion and histological variants with a poor prognosis. As in other cancers, early detection of recurrences improves outcomes and survival. I PET/CT can also be used to image the patients with DTC, similarly to I WBS. Compared with F-18 FDG PET/CT, its spatial resolution is only slightly degraded but increasing the imaging time reduces this difference. In addition, F-18 FDG PET/CT has been found helpful in the management of patients with anaplastic and medullary thyroid cancer. Other radiopharmaceuticals such as Ga-DOTATOC and F-18 DOPA may provide complimentary information to F-18 FDG PET/CT in the detection of recurrent thyroid cancer.     

F-18 fluorodeoxyglucose PET/CT as an imaging tool for staging and restaging cutaneous angiosarcoma of the scalp

Cutaneous angiosarcoma of the scalp is a rare highly aggressive malignant tumor that typically afflicts elderly patients and commonly presents with extensive local spread and distant metastasis. Distant metastases favor lung, liver, lymph nodes, and skin. Overall, the prognosis is poor. It differs from other soft tissue sarcomas in that the size of the lesion at presentation instead of tumor grade is the important prognostic factor. Optimal treatment is yet to be determined. Wide-margin complete excision with postoperative radiotherapy has been the most effective therapy. Chemotherapy and gene therapy have been used with some success. Local extent is critical in surgical planning, especially in the head and face, and is difficult to determine accurately with clinical examination and morphologic imaging tools. We report the case of a 70-year-old man diagnosed with multifocal angiosarcoma of the scalp. PET/CT imaging with F-18 2-fluoro-2-deoxyglucose (F-18 FDG) not only showed avid FDG uptake by an angiosarcoma (SUVmax = 10.7), but also simultaneously showed local extension of multifocal lesions with periosteal involvement and excluded metastatic abdominal nodal disease. PET/CT imaging after chemotherapy and before radiation therapy showed complete resolution of FDG uptake in the scalp and osseous lesions. Evaluation of more cases of this subset of soft tissue sarcoma with FDG PET/CT may suggest a possible role in not only staging angiosarcomas to determine the extent of local as well as distant disease, but also to potentially help determine response to therapy and early recognition of local or distant recurrence.     

Current status of PET in breast cancer imaging, staging, and therapy

The exact roles of PET in the imaging management of patients with known or suspected breast cancer are still in evolution. For assessing primary lesions, it is sometimes possible with PET to detect cancers occult on standard methods. This could be useful in high-risk patient populations, but in dense breasts, background FDG uptake is often higher than in women with fatty breasts, making identification of lesions < 1 cm in size improbable with current technologies. Distinguishing malignant from benign primary breast disease would seem better addressed by biopsy. With a positive predictive value of FDG PET for cancer over 96%, any FDG-avid breast lesion is highly suspicious and merits biopsy. Although PET in theory should be useful for depicting multifocal disease before surgery, the limitations in detecting small lesions in the breast limit the contribution of PET at present. It is most likely that PET will have a greater role in depicting primary breast lesions as dedicated PET imaging devices for the breast evolve. For axillary and internal mammary nodal staging, results with FDG PET are variable. Small nodal metastases < or = 5 mm will be missed by PET, whereas larger ones are more likely to be detected. PET can depict internal mammary nodes, but the accuracy of the method in this setting is not known, nor is there consensus on how identifying internal mammary node metastases will change treatment. Based on the available data, for pT1 breast lesions, PET, if negative, is not an adequate replacement for sentinel node surgery or axillary dissection. Results from the multicenter trial will be of great interest. Clearly PET can stage metastatic disease well. Bone scans with 18F- are exquisitely sensitive for metastases, and FDG is also very good. However, FDG PET can miss some blastic metastases to bone so at present FDG is not capable of excluding the presence of bone metastases. PET seems very well suited to detecting recurrences in soft tissues and the brachial plexus region in particular. The utility of PET in planning the treatment of individual patients appears promising. Although results must be confirmed in larger studies, it appears safe to conclude that failure of a chemotherapy regimen to decrease FDG uptake promptly in a breast cancer portends poor response. This does not hold true for hormonal therapy. At present, labeled estrogens are not widely available and cannot be recommended for clinical use. Thus, PET has shown considerable promise in breast cancer imaging, but in the author's experience is best applied to solve difficult imaging questions in specific patients and is not recommended for routine evaluation of the breast cancer patient. However, in larger primary tumors, the ability to use PET for staging and to plan treatment response suggest it will be more widely used. Additional studies with newer PET imaging devices and FDG and other tracers will help us better determine the role of PET in routine clinical care of the patient with known or suspected breast cancer. Certainly, this represent a fertile area for translational research studies over the next several years with the potential to significantly alter the way breast cancer is imaged and managed.     

F-18 fluorodeoxyglucose positron-emission tomography in the diagnosis of tumor recurrence and metastases in the follow-up of patients with breast carcinoma: a comparison to conventional imaging

AIM: To evaluate the role of F-18-fluorodeoxyglucose positron-emission tomography (F-18 FDG PET) in the follow-up of breast carcinoma in case of clinical suspicion of local recurrence or distant metastases and/or tumor marker increase in correlation to conventional imaging. MATERIAL AND METHODS: Retrospective analysis of the results of F-18 FDG PET (ECAT ART(R), Siemens CTI MS) of 62 patients (age 58.5 +/- 12.8) with surgically resected breast carcinoma (time interval after surgery, 86 +/- 82 months, mean follow-up 24 +/- 12.6 months). Patient- and lesion-based comparison with conventional imaging (CI) including mammography (MG), ultrasonography (US), computerized tomography (CT), magnetic resonance imaging (MRI), radiography (XR) and bone scintigraphy (BS). Furthermore, we evaluated the influence on tumor stage and therapeutic strategy. A visual qualitative evaluation of lesions was performed. RESULTS: On a patient base, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for detecting local recurrence or distant metastases were calculated to be 97%, 82%, 87%, 96% and 90% compared with 84%, 60%, 73%, 75% and 74% with CI. On a lesion base, significantly more lymph node (84 vs. 23, P < 0.05) and fewer bone metastases (61 vs. 97, P < 0.05) could be detected by using F-18 FDG PET compared with CI. Sclerotic bone lesions were predominantly detected by BS. On the other hand, there were several patients with more FDG positive bone lesions and also mixed FDG positive/Tc-99m methylenediphosphonate (MDP) negative and FDG negative/Tc-99m MDP positive metastases. In case of normal tumor markers, sensitivity, specificity, PPV, NPV and accuracy for detecting local recurrence or distant metastases were calculated to be 100%, 85.0%, 78.6%, 100% and 90.3% for FDG PET and 80%, 50%, 50%, 80% and 61.5% for CI. An upstaging could be observed in 9.7% (6/62) and downstaging in 12.9% (8/62), leading to a change in therapeutic regimen in 13 patients (21%). CONCLUSIONS: F-18 FDG PET demonstrates apparent advantages in the diagnosis of metastases in patients with breast carcinoma, compared with conventional imaging on a patient base. On a lesion base, significantly more lymph node and less bone metastases can be detected by using F-18 FDG PET compared with conventional imaging, including bone scintigraphy. In patients with clinical suspicion but negative tumor marker profile, too, F-18 FDG PET seems to be a reliable imaging tool for detection of tumor recurrence or metastases. Considering the high predictive value of F-18 FDG PET, tumor stage and therapeutic strategy will be reconsidered in several patients.     

PET recognition of pulmonary metastases on PET/CT imaging: impact of attenuation-corrected and non-attenuation-corrected PET images

Purpose The aims of this study were to assess the performance of FDG PET at PET/CT imaging for the detection of pulmonary metastases and to evaluate differences in lesion detectability on attenuation-corrected (AC) and non-attenuation corrected (NAC) PET images.Methods The institutional PET/CT database was searched for patients with pulmonary metastases of 3–60 mm in diameter. Ninety-two patients with 438 metastases to the lungs were included in the study. The primary tumours were 33 malignant melanomas, 12 carcinomas of unknown primary, 11 colorectal carcinomas, eight differentiated thyroid carcinomas, seven aggressive non-Hodgkins lymphomas, six head and neck cancers, three breast cancers, two prostate cancers and ten others. Lesion detectability was visually compared between PET and CT and between AC and NAC PET images using a five-point scale.Results Of the 438 pulmonary metastases, 174 were detected with FDG PET (39.7%), six of them on NAC images only (not significant). Visual scores were higher on NAC images in 41.4% and equal in 54.6% of lesions. The sensitivity of FDG PET increased significantly from 0.405 for metastases of 5–7 mm in diameter to 0.784 for lesions of 8–10 mm and to 0.935 for lesions measuring 11–29 mm in diameter. No metastases smaller than 5 mm in diameter were seen on PET images.Conclusion FDG PET/CT is useful for the assessment of pulmonary metastases. The frequency of lesion detection is similar for AC and NAC PET images. A reduced sensitivity of FDG PET has to be considered for lesions smaller than 11 mm in diameter.     

Superscan-like Hypermetabolic Lesions on Delayed FDG PET/CT Imaging in a Patient With Lung Cancer

ABSTRACT: A 69-year-old man with a lung mass underwent multiple-time-point FDG PET/CT imaging for diagnostic evaluation. The initial PET imaging (performed at 1 hour after tracer injection) revealed equivocal bone marrow uptake in the right iliac bone and proximal femurs in addition to lung and mediastinal lesions. The 3-hour delayed PET imaging, however, demonstrated widespread bone marrow metastases. Biopsies of the right lung mass and right iliac bone marrow were later performed and revealed a poorly differentiated squamous cell carcinoma in both sites. This case indicates the value of delayed FDG PET in detecting superscan-like hypermetabolic bone marrow lesions in patients with lung cancer.     

Metastatic brain lesions may demonstrate photopenia on FDG-PET

Metastatic brain lesions generally demonstrate hypermetabolic foci on fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) images. A large area of photopenia of the brain on FDG-PET is most likely consistent with a benign etiology. The author reports 2 cases of cerebral metastases from lung cancers, which display complete photopenia on FDG-PET. The brain is a special organ with high background uptake on PET and significant cytotoxic edema surrounding the metastatic deposits. In some cases, it is a dilemma to identify malignant intracranial foci on PET. Anatomic imaging, for example, MRI or CT correlation is needed for proper interpretation of brain PET on evaluation of metastases.     

18F-FDG PET as a single imaging modality in pediatric neuroblastoma: comparison with abdomen CT and bone scintigraphy

Objective

The purpose of this study was to evaluate the diagnostic performance of ¹⁸F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) as a single imaging agent in neuroblastoma in comparison with other imaging modalities.

Methods

A total of 30 patients with pathologically proven neuroblastoma who underwent FDG PET for staging were enrolled. Diagnostic performance of FDG PET and abdomen CT was compared in detecting soft tissue lesions. FDG PET and bone scintigraphy (BS) were compared in bone metastases. Maximal standardized uptake value (SUVmax) of primary or recurrent lesions was calculated for quantitative analysis.

Results

Tumor FDG uptake was detected in 29 of 30 patients with primary neuroblastoma. On initial FDG PET, SUVmax of primary lesions were lower in early stage (I–II) than in late stage (III–IV) (3.03 vs. 5.45, respectively, p = 0.019). FDG PET was superior to CT scan in detecting distant lymph nodes (23 vs. 18 from 23 lymph nodes). FDG PET showed higher accuracy to identify bone metastases than BS both on patient-based analyses (100 vs. 94.4 % in sensitivity, 100 vs. 77.8 % in specificity), and on lesion-based analyses (FDG PET: 203 lesions, BS: 86 lesions). Sensitivity and specificity of FDG PET to detect recurrence were 87.5 % and 93.8, respectively.

Conclusion

FDG PET was superior to CT in detecting distant LN metastasis and to BS in detecting skeletal metastasis in neuroblastoma. BS might be eliminated in the evaluation of neuroblastoma when FDG PET is performed.