111In-pentetreotide and123I-MIBG for detection and resection of lymph node metastases of a carcinoid not visualized by CT, MRI or FDG-PET

A patient with a history of a jejunal carcinoid and resection of liver metastases underwent CT, MRI and FDG-PET as well as somatostatin receptor scintigraphy using 111In-pentetreotide during follow-up. Octreoscan demonstrated one extrahepatic abdominal lesion with pathologic uptake, while the other imaging modalities failed to show a corresponding abnormality. For verification of this finding 123I-MIBG scintigraphy was performed. The MIBG scan confirmed the octreotide positive lesion and showed an additional abdominal lesion in the SPECT study. According to the scintigraphic results, radioguided surgery (RGS) was implemented using 123I-MIBG. This resulted in the intra-operative detection of two para- and pre-aortic lymph node metastases by the gamma probe and successful resection. An additional preaortal lymph node, suspicious by palpation, was also removed. Histopathology revealed metastases of a carcinoid tumor in all three specimens. In conclusion, the use of RGS facilitates successful removal of carcinoid metastatic lesions despite negative conventional imaging results. Secondly, 123I-MIBG scintigraphy may provide advantages over octreoscan for preoperative localization as well as radio-guided surgery of neuroendocrine metastatic lesions, if the involved site is located in proximity to highly octreotide-avid organs such as the kidneys or spleen.     

Comparison of [18F]FDG-PET and L-3[123I]-iodo-alpha-methyl tyrosine (I-123 IMT)-SPECT in primary lung cancer

OBJECTIVE: The aim of this study was to evaluate L-3[123I]-iodo-alpha-methyl tyrosine (IMT)-SPECT and FDG-PET in pulmonary lesions suspected to be lung cancer. METHODS: Whole body PET (measured transmission corrected emission scans) was performed 45 minutes after i.v. injection of 222-370 MBq (6-10 mCi) 18F-FDG on a Siemens PET scanner (ECAT EXACT 47) including 5-6 bed positions. 123I-IMT-SPECT (chest) was performed after injection of 370 MBq (10 mCi) with a dual head camera (Picker Prism 2000) and commercially available reconstruction algorithms. Ten patients (6 male and 4 female) with suspected lung cancer were investigated. The results were compared to histological findings after surgery or bronchoscopic biopsies and CT. RESULTS: 123I-IMT-SPECT and FDG-PET were able to detect all 9 cases of lung cancer (1-8 cm in diameter). One case was true negative. Both imaging methods were true positive with respect to mediastinal lymph node metastases in one patient. The tumor/background ratio was higher with PET (8.20 vs. 2.84). CONCLUSION: Despite the limited number of patients it may be concluded that IMT-SPECT as well as FDG-PET are suited to correctly diagnose lung cancer. Nevertheless, FDG-PET, if available, seems to be better suited because of the higher tumor/background ratio and better resolution.     

The clinical impact of18F-FDG PET in papillary thyroid carcinoma with a negative131I whole body scan: A single-center study of 108 patients

OBJECTIVE: To assess whether FDG PET could localize the recurrent or metastatic lesions in papillary thyroid cancer patients with negative radioiodine scan. METHODS: Whole body PET was performed after injecting 370-555 MBq of 18F-FDG in 108 patients, who were suspected of having recurrence or metastasis and whose 131I whole body scans were negative. Recurrence or metastasis occurred in 63 patients by pathology or clinical assessment, whereas 45 patients remained in remission. RESULTS: FDG PET revealed recurrence or metastases in 59 patients (sensitivity 93.7%), whereas thyroglobulin (Tg) levels were elevated in 41 (sensitivity 65.1%). In 35 of 45 patients in remission, FDG PET was negative (specificity 77.8%). When patients positive for antithyroglobulin antibody were excluded, the sensitivity and specificity of serum Tg became 84.8% and 46.9%, respectively. Compared to Tg measurement, FDG PET detected more metastatic lesions in cervical lymph nodes. Of 40 patients with a negative radioiodine scan showing diffuse hepatic uptake, metastases occurred in 23 patients and remission in 17. FDG PET showed 100% sensitivity and 76.5% specificity in the detection of recurrence in these 40 patients. CONCLUSION: FDG PET is useful for localizing recurrent or metastatic lesions in 131I scan-negative thyroid cancer patients. In particular, it is superior to serum Tg measurement for identifying metastases to cervical lymph nodes. We recommend its use in cases of negative radioiodine scan with diffuse hepatic uptake.     

Bone metastases from head and neck paragangliomas: uncommon MR findings in an uncommon condition--report of three cases

Malignancy (defined as metastatic disease) has been reported in nearly 5% of head and neck paragangliomas. Metastases preferentially target the lymph nodes, lung, liver, or bone. We describe three patients with multiple silent bone metastases exhibiting a fatty halo at MRI that coexisted with expansive bone lesions. In all cases, (123)I-metaiodobenzylguanidine ((123)MIBG) scintigraphy showed no abnormal tracer uptake, whereas (111)In-pentetreotide scintigraphy visualized a few silent bone metastases. These findings indicate that MRI should be included in the staging of paraganglioma patients with risk factors for malignancy.     

Clinical relevance of imaging proliferative activity in lung nodules

Purpose Recently, the thymidine analogue 3-deoxy-3[¹⁸F]fluorothymidine (FLT) has been introduced for imaging proliferation with positron emission tomography (PET). In this prospective study, we examined the accuracy of FLT for differentiation of benign from malignant lung lesions and for tumour staging.Methods A total of 47 patients with newly diagnosed pulmonary nodules on chest CT suspicious for malignancy were examined with FLT-PET in addition to routine staging procedures. A total of 43 patients also underwent 2-[¹⁸F]fluoro-2-deoxy-D-glucose (FDG) PET imaging. Within 2 weeks, patients underwent resective surgery or core biopsy of the pulmonary lesion.Results Histopathology revealed malignant lung tumours in 32 patients (20 non-small cell lung cancer, 1 small cell lung cancer, 1 pulmonary carcinoid, 1 non-Hodgkins lymphoma, nine metastases from extrapulmonary tumours) and benign lesions in 15 patients. Increased FLT uptake was exclusively related to malignant tumours. FLT-PET was false negative in two patients with non-small cell lung cancer, in the patient with a pulmonary carcinoid and in three patients with lung metastases. The sensitivity of FLT-PET for detection of lung cancer was 90%, the specificity 100% and the accuracy 94%. Fifteen out of 21 patients with lung cancer had mediastinal lymph node metastases. FLT-PET was true positive in 7/15 patients, resulting in a sensitivity of 53% for N-staging (specificity 100%, accuracy 67%). Clinical TNM stage was correctly identified in 67% (20/30) patients, compared to 85% (23/27) with FDG-PET.Conclusion FLT-PET has a high specificity for the detection of malignant lung tumours. Compared with FDG, FLT-PET is less accurate for N-staging in patients with lung cancer and for detection of lung metastases. FLT-PET therefore cannot be recommended for staging of lung cancer.     

Comparison of whole-body <Superscript>18</Superscript>F-FDG PET, <Superscript>99m</Superscript>Tc-MIBI SPET,and post-therapeutic <Superscript>131</Superscript>I-Na scintigraphy in the detection of metastatic thyroid cancer

The usefulness of fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in differentiated thyroid cancer (DTC) has been demonstrated by many investigators, but in only a small number of studies have FDG-PET images been compared with those obtained using other non-iodine tumour-seeking radiopharmaceuticals. In most of the studies, planar imaging was performed for comparison using thallium-201 chloride or technetium-99m 2-methoxyisobutylisonitrile (^99mTc-MIBI). Furthermore, FDG-PET studies were not always performed in the hypothyroid state with increased levels of thyroid stimulating hormone (TSH), which are known to increase FDG uptake by DTC. The aim of this study was to compare the ability of FDG-PET to detect metastatic DTC with that of ^99mTc-MIBI whole-body single-photon emission tomography (SPET) and post-therapeutic iodine-131 scintigraphy, evaluated under TSH stimulation. Nineteen patients (8 men, 11 women; age range, 38–72 years, mean 60 years; 17 thyroidectomised and 2 inoperable patients following ¹³¹I ablation of the remaining thyroid tissue; 16 papillary and 3 follicular carcinomas) with metastatic DTC underwent FDG-PET whole-body scan (WBS) and ^99mTc-MIBI SPET WBS at an interval of less than 1 week, followed by ¹³¹I therapy. The SPET images were reconstructed using the maximum likelihood expectation maximisation (ML-EM) method. All patients were hypothyroid at the time of each scan. ¹³¹I WBS was performed 3–5 days after oral administration of the therapeutic dose. A total of 32 lesions [10 lymph node (LN), 15 lung, 6 bone, 1 muscle] were diagnosed as metastases, as confirmed by histopathology and/or other imaging modalities (X-ray, US, CT, MRI, bone, ²⁰¹Tl and ¹³¹I scans). FDG-PET, ^99mTc-MIBI SPET and post-therapeutic ¹³¹I scintigraphy respectively revealed a total of 26 (81.3%), 20 (62.5%) and 22 (68.8%) lesions. These techniques respectively demonstrated nine (90.0%), eight (80.0%) and six (60.0%) LN metastases, and eleven (73.3%), seven (46.7%) and ten (66.7%) lung metastases. They each demonstrated five of the six bone metastases (83.3%). FDG-PET and ^99mTc-MIBI SPET were positive in 17 (78.3%) and 14 (63.6%) of the 22 ¹³¹I-positive lesions, respectively, and also in nine (90.0%) and six (60.0%) of the ten ¹³¹I-negative lesions, respectively. Three of the five ¹³¹I-positive and FDG-PET-negative lesions were miliary type lung metastases with a maximal nodular diameter of less than 10 mm. Comparison of FDG-PET with ^99mTc-MIBI SPET revealed concordant results in 24 lesions, and discordant results in eight lesions (seven with positive FDG-PET alone and one with positive ^99mTc-MIBI SPET alone). In conclusion: (a) even using whole-body SPET, FDG PET is superior to ^99mTc-MIBI in terms of ability to detect metastases of DTC; (b) the higher sensitivity of FDG-PET compared with the previous studies could partly be due to increased serum TSH.     

The usefulness of cardio-vascular visualization in the localization of mediastinal pheochromocytomas with I-131-MIBG

A case of malignant mediastinal paraganglioma showing moderate I-131 -MetaIodoBenzylGuanidine (MIBG) uptake in the pericardiac region is presented. The patient had already undergone unilateral adrenalectomy with obvious clinical and biochemical findings of pheochromocytoma. The initial thoraco-abdominal CT and adrenal MRI were negative. The MIBG scan prior to the operation showed moderately increased uptake in the left adrenal region. No pheochromocytoma was found in the removed gland and the clinical signs persisted following the operation. The second MIBG scan after surgery showed a moderate left mediastinal uptake site by which it was difficult to rule out intracardiac localization. Without moving the patient, succesive images of the tumor, myocardium and main mediastinal vessels were obtained by using the 24 hour activity of the initially injected 37 MBq Iodine-131-MIBG, 74 MBq Thallium-201 and 555 MBq Tc-99m-Human Serum Albumin (HSA), respectively. The superimposed bicolor images clearly showed the extracardiac localization of the tumor. The MRI scan confirmed this finding. Subsequent surgery found a malignant paraganglioma and metastatic mediastinal lymph nodes. We conclude that the visualization of the myocardium and the main mediastinal vessels with specific agents can be very useful in defining the exact location of I-131-MIBG detected mediastinal pheochromocytomas.     

Comparison of18FDG-PET with99mTc-HMDP scntigraphy for the detection of bone metastases in patients with breast cancer

OBJECTIVE: Bone is one of the most common sites of metastasis in breast cancer patients. Although bone scintigraphy is widely used to detect metastatic breast cancer, the usefulness of 18FDG-PET for detecting bone metastasis has not been clearly evaluated. The purpose of this study was to compare the diagnostic accuracy of 18FDG-PET with bone scintigraphy in detecting bone metastasis in breast cancer patients. METHODS: Forty-four women aged 35 to 81 years (mean, 56 years) with breast cancer were examined in this study. Both 18FDG-PET and bone scintigraphy were performed for each patient with 0-69 day intervals (mean, 11.5 days). The results of each image interpretation were compared retrospectively. Whole-body bones were classified into 9 anatomical regions. Metastases were confirmed at 45/187 regions in 14 patients by bone biopsy or clinical follow-up including other imaging techniques for a period of at least 6 months afterwards. RESULTS: On a region basis, the sensitivity, specificity, and accuracy of 18FDG-PET were 84%, 99% and 95%, respectively. Although these results were comparable to those of bone scintigraphy, the combination of 18FDG-PET and bone scintigraphy improved the sensitivity (98%) and accuracy (97%) of detection. False negative lesions of bone scintigraphy were mostly bone marrow metastases and those of 18FDG-PET were mostly osteoblastic metastases. 18FDG-PET was superior to bone scintigraphy in the detection of osteolytic lesions (92% vs. 73%), but inferior in the detection of osteoblastic lesions (74% vs. 95%). CONCLUSIONS: This study shows that 18FDG-PET tends to be superior to bone scintigraphy in the detection of osteolytic lesions, but inferior in the detection of osteoblastic lesions. 18FDG-PET should play a complementary role in detecting bone metastasis with bone scintigraphy.     

6. 18F-FDG Whole Body Positron Emission Tomography (PET) in the Detection of Unknown Primary Tumors

Purpose: To evaluate the utility of FDG-PET in detecting primary tumors in patients with metastatic disease from unknown primary tumors.Methods: 12 patients with metastases from unknown origin after unsuccessful conventional diagnostic procedures were studied. 5 had lymph node metastases (2 axillary, 2 cervical, 1 mediastinal), 3 multiple metastases, 1 in the lung, 1 in the cava vein, 1 in the brain and 1 in adrenal glands. Patients received 400MBq FDG intravenously, and whole body images were acquired 60 min. after injection with an ECAT EXACT HR+. PET results were compared with histological and clinical findings.Results: All but one metastatic lesion was identified by PET. Additional metastases were visualized in 4 patients. In one helped to guide biopsy for histological diagnosis. In 4/11 patients FDG-PET did not reveal lesions suspected to be primary tumor. FDG-PET identified primary tumor in 8/11 patients (breast: 2, pancreas: 2, base of tongue: 1, adrenal gland: 1, lung: 1, stomach: 1). In 4 of them (33% of total) primary tumor was confirmed either histologically or by the clinical evolution (breast: 2, lung: 1, pancreas: 1). In 1 patient FDG-PET was false positive (base of tongue). 3 patients positive FDG-PET have not yet been confirmed. FDG-PET influenced therapeutic procedures in 4 patients (33% of total). 2 underwent surgery (breast), 1 received specific chemotherapy (lung) and 1 palliative chemotherapy (pancreas).Conclusions: Our preliminary results suggest that FDG-PET is a non-invasive technique useful in the detection of unknown primary tumors, can influence in selecting appropriate therapeutic management and could guide biopsies for histologic analysis.     

Whole-body iodine-131 metaiodobenzylguanidine imaging for detection of bone metastases in patients with paraganglioma: comparison with bone scintigraphy

Iodine-131 metaiodobenzylguanidine (¹³¹I-MIBG) therapy is an effective treatment for patients with malignant paraganglioma for which surgical resection is not indicated. We performed high-dose ¹³¹I-MIBG therapy on two patients with malignant paraganglioma and multiple bone metastases. The bone metastases were diagnosed by magnetic resonance imaging (MRI). Metastatic bone lesions were evaluated by whole-body ¹³¹I-MIBG imaging and bone scintigraphy. Whole-body ¹³¹I-MIBG imaging showed extensive metastatic bone lesions, whereas conventional bone scintigraphy did not. There was a remarkable discrepancy between ¹³¹I-MIBG imaging and bone scintigraphy in the diagnosis of metastatic bone lesions of malignant paraganglioma in our two patients. High-dose ¹³¹I-MIBG imaging may detect early stages of bone metastases, compared with bone scintigraphy, in patients with malignant paraganglioma.     

Fluorine-18 2-deoxy-2-fluoro-D-glucose PET in the preoperative staging of breast cancer: comparison with the standard staging procedures

The present study compared the diagnostic accuracy of fluorine-18 2-deoxy-2-fluoro-D-glucose positron emission tomography (FDG-PET) with conventional staging techniques. The differentiation between malignant and benign lesions and the detection of multifocal disease, axillary and internal lymph node involvement, and distant metastases were evaluated. One hundred and seventeen female patients were prospectively examined using FDG-PET and conventional staging methods such as chest X-ray, ultrasonography of the breast and liver, mammography and bone scintigraphy. All patients were examined on a modern full-ring PET scanner. Histopathological analysis of resected specimens was employed as the reference method. The readers of FDG-PET were blinded to the results of the other imaging methods and to the site of the breast tumour. The sensitivity and specificity of FDG-PET in detecting malignant breast lesions were 93% and 75% respectively. FDG-PET was twofold more sensitive (sensitivity 63%, specificity 95%) in detecting multifocal lesions than the combination of mammography and ultrasonography (sensitivity 32%, specificity 93%). Sensitivity and specificity of FDG-PET in detecting axillary lymph node metastases were 79% and 92% (41% and 96% for clinical evaluation). FDG-PET correctly indicated distant metastases in seven patients. False-positive or false-negative findings were not encountered with FDG-PET. Chest X-ray was false-negative in three of five patients with lung metastases. Bone scintigraphy was false-positive in four patients. Three patients were upstaged since FDG-PET detected distant metastases missed with the standard staging procedure. It is concluded that, compared with the imaging methods currently employed for initial staging, FDG-PET is as accurate in interpreting the primary tumour and more accurate in screening for lymph node metastases and distant metastases. Due to a false-negative rate of 20% in detecting axillary lymph node metastases, FDG-PET cannot replace histological evaluation of axillary status.     

Hilar and mediastinal lymph node metastases in malignant melanoma.

Of 65 patients with intrathoracic metastases from melanomon, 35 had metastasis to hilar or mediastinal nodes. In 28 of these 35, hilar and mediastinal lymph node enlargement was radiographically visible, hilar node enlargement was more commonly seen than mediastinal node enlargement. Pulmonary nodules were demonstrated radiographically in 25 of the 28 patients. Although lymph node enlargement was often asymmetric, symmetric hilar adenopathy mimicking sarcoidosis occurred in five of the 28 patients. Seven patients had unilateral involvement of lung and hilar and mediastinal nodes. In patients with melanoma, indirect metastatic spread via pulmonary nodules to hilar and mediastinal nodes may account for the frequent association of node metastases with lung nodules, the occurrence of intrathoracic adenopathy in the absence of extrathoracic node metastases, and the common finding of unilateral lung and nodal disease.     

Fluorine-18 2-deoxy-2-fluoro-D-glucose PET in the preoperative staging of breast cancer: comparison with the standard staging procedures

The present study compared the diagnostic accuracy of fluorine-18 2-deoxy-2-fluoro-D-glucose positron emission tomography (FDG-PET) with conventional staging techniques. The differentiation between malignant and benign lesions and the detection of multifocal disease, axillary and internal lymph node involvement, and distant metastases were evaluated. One hundred and seventeen female patients were prospectively examined using FDG-PET and conventional staging methods such as chest X-ray, ultrasonography of the breast and liver, mammography and bone scintigraphy. All patients were examined on a modern full-ring PET scanner. Histopathological analysis of resected specimens was employed as the reference method. The readers of FDG-PET were blinded to the results of the other imaging methods and to the site of the breast tumour. The sensitivity and specificity of FDG-PET in detecting malignant breast lesions were 93% and 75% respectively. FDG-PET was twofold more sensitive (sensitivity 63%, specificity 95%) in detecting multifocal lesions than the combination of mammography and ultrasonography (sensitivity 32%, specificity 93%). Sensitivity and specificity of FDG-PET in detecting axillary lymph node metastases were 79% and 92% (41% and 96% for clinical evaluation). FDG-PET correctly indicated distant metastases in seven patients. False-positive or false-negative findings were not encountered with FDG-PET. Chest X-ray was false-negative in three of five patients with lung metastases. Bone scintigraphy was false-positive in four patients. Three patients were upstaged since FDG-PET detected distant metastases missed with the standard staging procedure. It is concluded that, compared with the imaging methods currently employed for initial staging, FDG-PET is as accurate in interpreting the primary tumour and more accurate in screening for lymph node metastases and distant metastases. Due to a false-negative rate of 20% in detecting axillary lymph node metastases, FDG-PET cannot replace histological evaluation of axillary status.     

Compare FDG-PET and Tc-99m tetrofosmin SPECT to detect metastatic thyroid carcinoma

RATIONALE AND OBJECTIVES: The effectiveness of 18-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) and technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of neck and chest was evaluated to detect metastatic lesions in well-differentiated thyroid carcinoma after nearly total thyroidectomy and radioiodine (I-131) treatment who present with elevated serum human thyroglobulin levels but negative I-131 whole body scan. MATERIALS AND METHODS: Twenty-three patients with differentiated thyroid carcinoma who underwent nearly total thyroidectomy and I-131 treatments were included in this study. RESULTS: All of the 23 patients had negative I-131 whole body scan and elevated human thyroglobulin levels under thyroid-stimulating hormone stimulation. Metastatic lesions were detected by FDG-PET in 20 patients, while Tc-99m TF SPECT revealed metastatic lesions in only 11 of the 20 patients. Both FDG-PET and Tc-99m TF SPECT failed to demonstrate miliary pulmonary metastases in two of the remaining three patients. The other patient did not show any lesion on FDG-PET, Tc-99m TF SPECT, chest computed tomography, or other imaging techniques. CONCLUSION: This study demonstrated that FDG-PET is more sensitive than Tc-99m TF SPECT to detect metastatic lesions in differentiated thyroid carcinoma with elevated human thyroglobulin but negative I-131 whole body scan. However, miliary pulmonary metastases could be missed by the both techniques.     

The usefulness of FDG positron emission tomography for the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer: a comparative study with X-ray computed tomography

We evaluated the usefulness of fluorine-18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) in the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer and then compared the findings with the results of X-ray CT by region based on the histological diagnoses. We examined 29 patients with non-small cell lung cancer. One hundred and thirty-two mediastinal lymph nodes were surgically removed and the histological diagnoses were confirmed. FDG PET images, including 146 mediastinal regions, were visually analysed and the mediastinal lymph nodes were scored as positive when the FDG uptake was higher than that in the other mediastinal structures. On the X-ray CT scans, any mediastinal lymph nodes with a diameter of 10 mm or larger were scored as positive. All three examinations were successfully performed on 71 regions. For FDG PET, we found a sensitivity of 76%, a specificity of 98% and an accuracy of 93%. On the other hand, for X-ray CT a sensitivity of 65%, a specificity of 87% and an accuracy of 82% were observed. A significant difference was observed in respect of both specificity and accuracy (P<0.05). Based on the above findings, FDG PET is suggested to be superior to X-ray CT when used for the detection of mediastinal lymph node metastases in patients with non-small cell lung cancer.     

Evaluation of lung cancer by 99mTc-tetrofosmin SPECT: comparison with [18F]FDG-PET

PURPOSE: The purpose of this study was to clarify the validity of (99m)Tc-tetrofosmin SPECT (TF-SPECT) in the evaluation of lung cancer in comparison with [18F]fluorodeoxyglucose ([18F]FDG-PET). METHOD: Twenty-one patients with biopsy-proven non-small cell lung cancer were examined by both TF-SPECT (early and delayed images) and FDG-PET within a week of each study. Lung cancers were analyzed visually and semiquantitatively using the ratio of lesion to background counts (L/B ratio). Mediastinal lymph node metastases were analyzed only visually. RESULTS: Both early and delayed TF images could detect 18 of 21 lung cancers on visual analysis (85.7%), whereas FDG-PET could detect all the lesions (100%). The L/B ratio of TF-SPECT was significantly higher in delayed than in early images (1.79 +/- 0.55 vs. 1.56 +/- 0.40; p < 0.001). However, the L/B ratio of FDG-PET was 8.85 +/- 3.05, significantly higher than those of both TF images (p < 0.0001). In the assessment of mediastinal involvement, TF-SPECT was 40.0% sensitive, 100% specific, and 71.4% accurate, whereas FDG-PET was 80.0% sensitive, 81.8% specific, and 81.0% accurate. CONCLUSION: Although the detection sensitivity was far better than expected, TF-SPECT is not considered to be an alternative to FDG-PET in the evaluation of malignant pulmonary lesions because of its significantly low L/B ratio. TF-SPECT has poor sensitivity for mediastinal lymph node metastases and is useless for staging patients with lung cancer.     

Impact of [<Superscript>18</Superscript>F]FDG-PET on the primary staging of small-cell lung cancer

Purpose The purpose of this study was to evaluate the impact of [¹⁸F]fluorodeoxy-d-glucose positron emission tomography (FDG-PET) on the primary staging of patients with small-cell lung cancer (SCLC).Methods FDG-PET was performed in 120 consecutive patients with SCLC during primary staging. In addition, brain examinations with both FDG-PET and cranial magnetic resonance imaging (MRI) or computed tomography (CT) were performed in 91 patients. Results of FDG-PET were compared with those of conventional staging procedures. FDG-PET detected markedly increased FDG uptake in the primary tumours of all 120 patients (sensitivity 100%).Results Complete agreement between FDG-PET results and other staging procedures was observed in 75 patients. Differences occurred in 45 patients at 65 sites. In 47 sites the FDG-PET results were proven to be correct, and in ten, incorrect. In the remaining eight sites, the discrepancies could not be clarified. In 14/120 patients, FDG-PET caused a stage migration, correctly upstaging ten patients to extensive disease and downstaging three patients by not confirming metastases of the adrenal glands suspected on the basis of CT. Only 1/120 patients was incorrectly staged by FDG-PET, owing to failure to detect brain metastases. In all cases the stage migration led to a significant change in the treatment protocol. Sensitivity of FDG-PET was significantly superior to that of CT in the detection of extrathoracic lymph node involvement (100% vs 70%, specificity 98% vs 94%) and distant metastases except to the brain (98% vs 83%, specificity 92% vs 79%). However, FDG-PET was significantly less sensitive than cranial MRI/CT in the detection of brain metastases (46% vs 100%, specificity 97% vs 100%).Conclusion The introduction of FDG-PET in the diagnostic evaluation of SCLC will improve the staging results and affect patient management, and may reduce the number of tests and invasive procedures.     

Use of fusion images of I-131 metaiodobenzylguanidine, SPECT, and magnetic resonance studies to identify a malignant pheochromocytoma

Pheochromocytoma is a chromaffin tumor in which 10% are extra-adrenal and 10% are malignant. I-131 metaiodobenzylguanidine (MIBG) scintigraphy has an important role in the identification of these tumors and investigation of metastatic lesions. The authors describe a 36-year-old woman who underwent resection of a malignant left adrenal pheochromocytoma who was thought to have metastases in the liver and para-aortic lymph nodes. Fusion images of I-131 MIBG SPECT and magnetic resonance studies were obtained to properly identify the metastatic lesions. These fusion images helped greatly in subsequent surgery.     

Comparison of MET-PET and FDG-PET for differentiation between benign lesions and malignant tumors of the lung

OBJECTIVE: We retrospectively assessed and compared the usefulness of 11C-methionine (MET)-PET with that of 18F-FDG-PET for the differentiation between benign lesions and malignant tumors of the lung. METHODS: We examined 101 patients with a suspected lung tumor including 79 patients with primary lung cancer and 22 patients with benign lesions. One hundred and forty PET studies (46 studies with MET-PET and 94 studies with FDG-PET) were performed. Both MET-PET and FDG-PET were performed on 39 patients. The MET-PET was performed 15 minutes after the administration of 67-740 MBq of MET, and FDG-PET 45 minutes after the administration of 30-437 MBq of FDG. The results were then evaluated by the standardized uptake value (SUV). RESULTS: The MET uptake in lung cancer was 3.69+/-1.22 (n = 37) which was significantly higher than that in benign lesions 1.81+/-1.04 (n = 9) (p < 0.001). The sensitivity, specificity and accuracy of MET-PET were 83.8%, 88.9% and 84.8%, respectively, when 2.66 of SUV was used as the cutoff value. The FDG uptake in lung cancer was 5.94+/-2.89 (n = 75) and was also significantly larger than that in benign lesions 2.46+/-1.01 (n = 19) (p < 0.001). The sensitivity, specificity and accuracy of FDG-PET were 81.3%, 78.9% and 80.9%, respectively (cutoff = 3.20). The MET uptake in the lesions correlated significantly with FDG uptake (r = 0.71, p < 0.001). According to an ROC analysis, the area under the curve for MET-PET (area = 0. 833) was higher than that for FDG-PET (area = 0.828), but the difference was not statistically significant. Furthermore, the combined use of MET-PET and FDG-PET did not improve the diagnostic ability. CONCLUSIONS: In conclusion, both MET-PET and FDG-PET were considered to be equally useful for the differential diagnosis of lung tumors. Furthermore, MET uptake in lung lesions was found to correlate significantly with FDG uptake.     

9. Assessment of Intrathoracic Metastatic Lung Cancer using FDG-PET and CT of the Thorax

Purpose: The purpose of this study was to assess the accuracy in localizing mediastinal, hilar and intraparenchymal lymphadenopathy in patients with primary lung carcinomas, using FDG-PET and CT of the thorax and to correlate with surgical pathology.Method: Thirty-five patients with primary lung carcinomas and minimal metastatic lymph node involvement, (either N solidus in circle or N1 disease) underwent FDG-PET and CT of the thorax prior to surgical intervention. Both FDG-PET and CT of the thorax were blindly read independent of one another.Results: Histologically, 23 patients had negative lymph nodes (N solidus in circle) and 12 patients had N1 disease. The imaging performance characteristics for FDG-PET and CT of the thorax in N solidus in circle/N1 disease was evaluated and reported in Table 1.Conclusion: This study demonstrates the higher specificity, accuracy, PPV, and NPV of FDG-PET over CT of the thorax in patients with minimal lymph node disease.