Mitsuru Taniguchi

Diffusion-Weighted Imaging Is Superior to Positron Emission Tomography in the Detection and Nodal Assessment of Lung Cancers

BACKGROUND Diffusion-weighted magnetic resonance imaging (DWI) makes it possible to detect malignant tumors based on the difference in the diffusion of water molecules among tissues. The aims of this study are to examine the usefulness of DWI compared with positron emission tomography-computed tomography (PET-CT) in the assessment of lung cancer, and the relationships between the apparent diffusion coefficient (ADC) value and several pathologic factors. METHODS Sixty-three patients with primary non-small cell lung cancer were enrolled in this study. The DWI and PET-CT were performed before surgery. There were 42 adenocarcinomas, 19 squamous cell carcinomas, and 2 other cell types. RESULTS Sixty-one lung cancers (97%) were detected visually with DWI. This was significantly higher than 54 lung cancers (86%) with PET-CT. The accuracy for N staging by DWI was 0.81 (51 of 63), which was not significantly higher than 0.71 (45 of 63) by PET-CT. The sensitivity (0.75) for individual metastatic lymph node stations by DWI was significantly higher than that (0.48) by PET-CT. The specificity for individual nonmetastatic lymph node stations was 0.99 by DWI and 0.97 by PET-CT, respectively. The accuracy (0.95) for the diagnosis of lymph node stations by DWI was significantly higher than that (0.90) by PET-CT. There was a weak reverse relationship (correlation coefficient: 0.286) between the ADC value and the maximum standardized uptake value, but no relationship between ADC value and tumor size. The ADC values increased while the cell differentiation increased. CONCLUSIONS Diffusion-weighted magnetic resonance imaging is superior to PET-CT in the detection of primary lesions and nodal assessment of non-small cell lung cancers.

Relationships between EGFR mutation status of lung cancer and preoperative factors - are they predictive?

BACKGROUND The epidermal growth factor receptor (EGFR) mutation status of lung cancer is important because it means that EGFR-tyrosine kinase inhibitor treatment is indicated. The purpose of this prospective study is to determine whether EGFR mutation status could be identified with reference to preoperative factors. MATERIALS AND METHODS One hundred-forty eight patients with lung cancer (111 adenocarcinomas, 25 squamous cell carcinomas and 12 other cell types) were enrolled in this study. The EGFR mutation status of each lung cancer was analyzed postoperatively. RESULTS There were 58 patients with mutant EGFR lung cancers (mutant LC) and 90 patients with wild-type EGFR lung cancers (wild-type LC). There were significant differences in gender, smoking status, maximum tumor diameter in chest CT, type of tumor shadow, clinical stage between mutant LC and wild-type LC. EGFR mutations were detected only in adenocarcinomas. Maximum standardized uptake value (SUVmax:3.66±4.53) in positron emission tomography-computed tomography of mutant LC was significantly lower than that (8.26±6.11) of wild-type LC (p<0.0001). Concerning type of tumor shadow, the percentage of mutant LC was 85.7% (6/7) in lung cancers with pure ground glass opacity (GGO), 65.3%(32/49) in lung cancers with mixed GGO and 21.7%(20/92) in lung cancers with solid shadow (p<0.0001). For the results of discriminant analysis, type of tumor shadow (p=0.00036) was most significantly associated with mutant EGFR. Tumor histology (p=0.0028), smoking status (p=0.0051) and maximum diameter of tumor shadow in chest CT (p=0.047) were also significantly associated with mutant EGFR. The accuracy for evaluating EGFR mutation status by discriminant analysis was 77.0% (114/148). CONCLUSIONS Mutant EGFR is significantly associated with lung cancer with pure or mixed GGO, adenocarcinoma, never-smoker, smaller tumor diameter in chest CT. Preoperatively, EGFR mutation status can be identified correctly in about 77 % of lung cancers.

Diagnostic Performance of Diffusion Weighted Imaging of Malignant and Benign Pulmonary Nodules and Masses: Comparison with Positron Emission Tomography

BACKGROUND Diffusion-weighted imaging (DWI) makes it possible to detect malignant tumors based on the diffusion of water molecules. However, it is uncertain whether DWI has advantages over FDG-PET for distinguishing malignant from benign pulmonary nodules and masses. MATERIALS AND METHODS One hundred- forty-three lung cancers, 17 metastatic lung tumors, and 29 benign pulmonary nodules and masses were assessed in this study. DWI and FDG-PET were performed. RESULTS The apparent diffusion coefficient (ADC) value (1.27 ± 0.35 ?10-3 mm2/sec) of malignant pulmonary nodules and masses was significantly lower than that (1.66 ± 0.58 ?10-3 mm2/sec) of benign pulmonary nodules and masses. The maximum standardized uptake value (SUV max: 7.47 ± 6.10) of malignant pulmonary nodules and masses were also significantly higher than that (3.89 ± 4.04) of benign nodules and masses. By using optimal cutoff values for ADC (1.44?10-3 mm2/sec) and for SUV max (3.43), which were determined with receiver operating characteristics curves (ROC curves), the sensitivity (80.0%) of DWI was significantly higher than that (70.0%) of FDG-PET. The specificity (65.5%) of DWI was equal to that (65.5%) of FDG-PET. The accuracy (77.8%) of DWI was not significantly higher than that (69.3%) of FDG- PET for pulmonary nodules and masses. As the percentage of bronchioloalveolar carcinoma (BAC) component in adenocarcinoma increased, the sensitivity of FDG-PET decreased. DWI could not help in the diagnosis of mucinous adenocarcinomas as malignant, and FDG-PET could help in the correct diagnosis of 5 out of 6 mucinous adenocarcinomas as malignant. CONCLUSIONS DWI has higher potential than PET in assessing pulmonary nodules and masses. Both diagnostic approaches have their specific strengths and weaknesses which are determined by the underlying pathology of pulmonary nodules and masses.

Renal artery pseudoaneurysm demonstrated on radionuclide scintiscan.

The authors present a case of renal artery pseudoaneurysm demonstrated on the Tc-99m DTPA dynamic study. On the blood flow image, localized increased activity was noted in the area of the renal hilus. This activity disappeared on the subsequent sequential renal images.

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.

Gallium-67-citrate scintigraphy of primary renal lymphoma

We present a case of primary renal lymphoma, which is a rare entity and poses diagnostic challenge. Ultrasound and CT scan demonstrated a nonspecific solid tumor in the left kidney.67Ga-citrate scintigraphy demonstrated an intense uptake in the tumor, which led to a correct diagnosis, so that we could spare unnecessary laparotomy and possible nephrectomy.

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.

F-18 FDG-PET imaging in rectal leiomyoma.

We report a case of leiomyoma of the rectum, which is rarely encountered. F-18 fluorodeoxyglucose positron emission tomography (F-18 FDG PET) is a useful modality in detecting various tumors, including rectal ones. We evaluated a patient with rectal leiomyoma, using F-18 FDG PET imaging which detected abnormally increased uptake in the pelvis. The standardized uptake value of the highest FDG uptake was 8.6. We succeeded in demonstrating tumor uptake by rectal leiomyoma, using F-18 FDG PET imaging.

Ga-67 scintigraphy of malignant lymphoma of the uterus.

Primary uterine malignant lymphoma is frequently not prospectively diagnosed because of its rarity and nonspecific clinical findings. The authors present a case of primary uterine malignant lymphoma, in which ultrasonography, CT scan, and MRI revealed nonspecific findings, whereas Ga-67 scintigraphy showed intense uptake in the uterine mass that was highly suggestive of malignant lymphoma.