Manabu Oguchi

FDG PET in the evaluation of the aggressiveness of pulmonary adenocarcinoma : correlation with histopathological features

2-[Fluorine-18]fluoro-2-deoxy-d-glucose (FDG) uptake within the primary lesion correlates with survival on positron emission tomography (PET) studies of patients with non-small cell lung cancer. The more metabolically active the tumour, the worse the outcome. The aim of this study was to determine whether a correlation exists between aggressiveness as determined by pathology and the findings of FDG PET in pulmonary adenocarcinoma. Thirty-five patients with 38 adenocarcinomas of the lung were studied. All patients underwent thoracotomy within 4 weeks of the FDG PET study. For semiquantitative analysis, standardized uptake values (SUVs) were calculated. Patients were classified into high SUV (⩾4.0) and low SUV (<4.0) groups. The degree of FDG uptake (SUVs) in primary lung lesions was correlated with the histopathological features of aggressiveness (pleural involvement, vascular invasion or lymphatic permeation). The mean SUV of aggressive adenocarcinomas (4.36±1.94, n = 22) was higher than that of non-aggressive ones (1.53±0.88, n = 16) (P<0.0001). Tumours with a high FDG uptake have a significantly higher likelihood of aggressiveness than those with a low FDG uptake (P = 0.0004). Analysis by the Kaplan-Meier methods revealed that the groups had different prognoses (log-rank test, P = 0.0099). The high SUV group had a significantly worse prognosis. In conclusion, a correlation was seen between aggressiveness as determined by pathology and glucose metabolism as measured by FDG PET in adenocarcinoma of the lung. FDG PET may be used as a non-invasive diagnostic technique in measuring aggressiveness and prognosis in patients with pulmonary adenocarcinoma.

Value of whole-body FDG PET in management of lung cancer

Abstract18F-fluorodeoxyglucose (FDG) PET imaging provides physiologic and metabolic information that characterizes lesions that are indeterminate by CT. FDG PET imaging is sensitive to the detection of lung cancer in patients who have indeterminate lesions on CT, whereas low grade malignancy such as bronchioloalveolar carcinoma and carcinoid may be negative on FDG PET. The specificity of PET imaging is less than its sensitivity because some inflammatory processes, such as active granulomatous infections, avidly accumulate FDG. This possibility should be kept in mind in the analysis of PET studies of glucose metabolism aimed at differentiating malignant from benign solitary pulmonary nodules. FDG uptake is considered to be a good marker of cell differentiation, proliferative potential, aggressiveness, and the grade of malignancy in patients with lung cancer. FDG PET accurately stages the distribution of lung cancer. Several studies have documented the increased accuracy of PET compared with CT in the evaluation of the hilar and mediastinal lymphnode status in patients with lung cancer. Whole-body PET studies detect metastatic disease that is unsuspected by conventional imaging. Management changes have been reported in up to 41% of patients on the basis of the results of whole-body studies. Whole-body FDG PET is also useful for the detection of recurrence. Several studies have indicated that the degree of FDG uptake in primary lung cancer can be used as an independent prognostic factor. Thus, whole-body FDG PET is clinically very useful in the management of lung cancer.

Chordoid glioma of the third ventricle: CT and MR findings.

We present a case of chordoid glioma involving the third ventricle in a 42-year-old woman. CT and MR showed a homogeneously enhancing mass occupying the third ventricle, with a cystic component. Chordoid glioma should be included in the differential diagnosis of uncommon masses of the third ventricle in middle-aged women.

P-glycoprotein expression is associated with FDG uptake and cell differentiation in patients with untreated lung cancer.

In vitro studies demonstrated that the accumulation of 2-deoxy-D-glucose was reduced in multidrug resistant cell lines. In animal study, it has been suggested that 2-[18F]fluoro-2-deoxy-D-glucose (FDG) may be a marker for multidrug resistance (MDR). The aim of this clinical study was to compare MDR characteristics by immunohistochemical assay with FDG uptake and investigate whether FDG is a marker for MDR in patients with untreated lung cancer. Forty-seven patients with 49 untreated lung cancers, who had undergone both preoperative FDG PET imaging and thoracotomy, were enrolled in this study. Before surgery, FDG PET was performed 40 min after injection, and standardized uptake values (SUVs) were obtained. Patients were classified into low-SUV (⩽5) and high-SUV (>5) groups. After surgery, the expression of P-glycoprotein (Pgp) was investigated by immunohistochemistry, and the lung cancer FDG uptake was analysed for possible association with Pgp expression. The strong intensity of Pgp immunoreactivity was seen only in the low-SUV group. The percentage of the Pgp positive area was significantly lower in the high-SUV group (21.7±13.4%) than in the low-SUV group (44.1±29.7%) (P = 0.015). In the high-SUV group, the percentage of Pgp positive area did not exceed 50%. In lung adenocarcinoma, the intensity of Pgp immunoreactivity and the percentage of Pgp positive area increased with degree of cell differentiation, while FDG uptake decreased with degree of cell differentiation. Bronchioloalveolar carcinoma, in particular, showed overexpression of Pgp and modest uptake of FDG. In conclusion, Pgp expression was found to be inversely related to FDG uptake in untreated lung cancer. Pgp expression correlated with the degree of cell differentiation in adenocarcinomas, whilst FDG uptake was inversely related to cell differentiation. FDG may be an in vivo marker for MDR in patients with untreated lung cancer.

Changes in regional cerebral blood flow in irradiated regions and normal brain after stereotactic radiosurgery

Objective: To elucidate the radiation effect on the normal brain after stereotactic radiosurgery (SRS), we evaluated the change in regional cerebral blood flow (CBF) in targeted and extra-targeted areas according to the radiation dose given.Methods: Thirteen patients who underwent SRS for brain tumors or arteriovenous malformations were included in this study. Maximum radiation doses to the lesion ranged from 24 to 37 Gy. Mean and regional CBF were measured by99mTc-HMPAO scintigraphy with graphic analysis, performed at before, 2 weeks and 3 months (5 patients) after SRS. Under the co-registration with the CT with superimposed isodose distribution, ROIs were set on target (37-20 Gy), peri-target (20-5 Gy) and out-of-field (5-2 Gy and less than 2 Gy) areas on the quantitative SPECT images.Results: Significant reductions in mean CBF (by 7%) and regional CBF in the peri-target areas (by 5–7%) and out-of-field areas (by 6–22%) were recognized at 2 weeks and 3 months after SRS. Regional CBF in the target and peri-target areas did not significantly change, presumably because there was little or no normal tissue in these areas.Conclusion: These results suggest that subclinical regional CBF reduction occurs after SRS in the normal brain in out-of-field of radiation.

Calcified mediastinal metastases from ovarian cancer imaged with Tc-99m MDP SPECT

A 41-year-old woman was hospitalized for dyspnea. Seventeen years earlier, she had had surgery for papillary ovarian cancer. Her chest CT revealed massive calcified mediastinal lymph node metastases and tracheal stenosis. Surgery confirmed the presence of calcified metastatic ovarian carcinoma of the mediastinal lymph nodes, and a tracheobronchial stent was inserted. Five months later, Tc-99m MDP bone scintigraphy showed no bone metastases, but there was remarkable radionuclide uptake in the right supraclavicular region and the mediastinum. SPECT images precisely visualized the radionuclide accumulation in the calcified lymph node metastases.

Single photon emission CT images in a case of intraventricular neurocytoma

Although Tc-99m HMPAO uptakes in various brain tumors have been reported, SPECT images of neurocytoma have not been described. The authors report a patient with intraventricular neurocytoma (IN) who demonstrated significant uptake of Tc-99m HMPAO and Tl-201 Cl before brain biopsy. Residual tumor after biopsy showed significant uptake of I-123 IMP on early SPECT images, but this uptake was decreased on delayed images. The three radionuclides seem to have different uptake mechanisms.

Tumor-like accumulation on Tl-201 SPECT in subacute hemorrhagic cerebral infarction.

A 75-year-old woman was hospitalized for left hemiplegia. Intratumoral hematoma was considered likely based on the findings of computed tomographic (CT) images, and T1-201 SPECT was performed for further differentiation. Early SPECT images showed tumor-like accumulation in the right basal ganglia. However, the accumulation was washed out on delayed SPECT. Final diagnosis by a follow-up study was subacute hemorrhagic infarction. Although early T1-201 SPECT may show positive results for subacute hemorrhagic infarction, a delayed T1-201 SPECT can show a wash-out pattern that may be specific for this infarction. Early T1-201 SPECT may show tumor-like accumulation for subacute hemorrhagic infarction. This should be kept in mind in the analysis of T1-201 SPECT studies when cerebral infarction is being differentiated from brain tumor.

Marked Uptake of Tl-201 in Intracranial Extracerebral Cavernous Hemangioma

A case of intracranial extracerebral cavernous hemangioma in the middle fossa is presented. A 78-year-old woman was hospitalized because of progressive gait disturbance and left eyelid ptosis. Enhanced CT images showed a markedly enhanced tumor in the middle fossa. The diagnosis based on CT scans was a parasellar meningioma. TI-201 SPECT scans showed a prominent ring-like accumulation in the tumor on early imaging. TI-201 uptake became reduced and remained scant on delayed images. After surgery, the pathologic diagnosis was intracranial extracerebral cavernous hemangioma. The described TI-201 uptake pattern may be specific for intracranial extracerebral cavernous hemangioma.

Advanced Oesophageal Carcinoma in an 84-year-old Treated with Chemoradiotherapy

We present a case of advanced oesophageal cancer with cardiac invasion in an 84-year-old male presenting with dysphagia and general malaise. Histological analysis of an endoscopic biopsy specimen revealed a poorly differentiated squamous cell carcinoma. Computed tomography indicated a thickened oesophageal wall that was compressing the left atrium, suggesting invasion of the heart, and oesophagography revealed a polypoid lesion 9 cm in length. No distant metastases were seen on computed tomography. The patient was given chemotherapy with 10 mg/m2 cisplatin on days 1 and 4 every week for 5 weeks and concurrent radiotherapy at a dose of 2 Gy five times per week (total dose 52 Gy). After 4 weeks, the mass was no longer visible on oesophagography or endoscopic examination. The patient was free of recurrence and metastases for 4.5 years. In conclusion, chemoradiotherapy may be curative in elderly patients with unresectable oesophageal carcinoma.