Nobuyuki Takeyama

Comparison of 40 and 60 milliliters of contrast in assessment of the carotid artery by computed tomography angiography

Background: Although fast acquisition of multidetector-row computed tomography (MDCT) can make it possible to acquire sufficient early vascular enhancement using small volumes and high concentrations of contrast material (CM), there are still some problems with nephrotoxicity and costs related to CM. Purpose: To compare the qualitative and quantitative performance in cervicocranial CT angiography (CTA) using two different iodine volumes and concentrations of CM. Material and Methods: CTA ranging from the aortic arch (AA) to distal to the circle of Willis (cW) was performed on a 32-MDCT system. Fifty-eight patients were randomly divided into two groups: group A (29 patients) received 60 ml of 300 mg I/ml CM, and group B (the other 29 patients) received 40 ml of 370 mg I/ml CM. Time to peak arterial enhancement at cW (Tc) was calculated. As scan speed was 96.9 mm/s and injection rate was 4.0 ml/s, scanning delay was individually decided according to Tc and scan duration between AA and cW. Arterial attenuation along the z-axis at eight points in the carotid-cerebral artery and venous attenuation of the internal jugular vein (IJV) at carotid bifurcation were measured. Mean attenuation values were then quantitatively analyzed. Postprocessing images were qualitatively assessed. Results: Arterial attenuation profiles revealed maximum attenuation at the distal common carotid artery in both groups. Although there were no significant differences in mean arterial attenuation in group A versus group B (402±70 HU vs. 407±67 HU; P=0.78), venous attenuation of the IJV was lower in group B than in group A (114±57 HU vs. 224±81 HU; P<0.001). Although arterial images demonstrated no difference qualitatively between the two groups, the venous contamination of IVC was less prominent in group B. Conclusion: Although a different amount of CM was administered in both groups, quantitative and qualitative arterial images did not show significant differences between the two groups.

MR Imaging of Fetuses to Evaluate Placental Insufficiency

Purpose: To evaluate morphological and signal intensity (SI) changes of placental insufficiency on magnetic resonance imaging (MRI) and to assess morphological changes and decreased flow voids (FVs) on T2-weighted rapid acquisition with relaxation enhancement (RARE) images for diagnosing placental insufficiency. Methods: Fifty singleton fetuses underwent MRI using a 1.5-T MR scanner. Placental thickness, area, volume, SI, amniotic fluid SI, and size of FVs between the uterus and the placenta were measured on MR images. Two radiologists reviewed T2-weighted RARE images for globular appearance of the placenta and FVs between the uterus and the placenta. Data were analyzed using t-tests, McNemar’s tests, and areas under the receiver operating characteristic curve (AUCs) at 5% level of significance. Results: Twenty-five of the 50 pregnancies were categorized as having an insufficient placenta. Significant differences were observed between insufficient and normal placentas in mean placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs (49.0 mm vs. 36.9 mm, 1.62 × 104 mm2 vs. 2.67 × 104 mm2, 5.13 × 105 mm3 vs. 6.56 × 105 mm3, 0.549 vs. 0.685, and 3.4 mm vs. 4.3 mm, respectively). The sensitivity and accuracy using globular appearance plus decreased FVs were greater than those using decreased FVs (P < 0.01). There was no significant difference among AUCs using globular appearance and decreased FVs, and globular appearance plus decreased FVs. Conclusions: Placental insufficiency was associated with placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs. Evaluating FVs on T2-weighted RARE images can be useful for detecting placental insufficiency, particularly in placentas without globular appearance on MR images.

A case of pulmonary papillary adenoma: Possible relationship between tumor histogenesis/tumorigenesis and fibroblast growth factor receptor 2 IIIb

Pulmonary papillary adenoma is a rare tumor. We analyzed a tumor which appeared in a 16‐year‐old Japanese woman. The tumor histologically showed papillary proliferation of one‐layered tumor cells coating inflammatory fibrovascular cores. At the periphery of the tumor, the tumor cells grew in a lepidic fashion. The tumor cells were confirmed as type‐II pneumocytes with electron‐microscope. In this study, using immunohistochemistry, in situ hybridization and real‐time reverse transcription polymerase chain reaction, we examined the expressions and quantities of fibroblast growth factor 10 (FGF10), keratinocyte growth factor (KGF) and fibroblast growth factor receptor 2 (FGFR2) IIIb, based on the extent of their abilities of proliferation and differentiation of type II pneumocytes. The tumor cells expressed FGFR 2 and produced 350 times more FGFR2IIIb messenger RNA (mRNA) than did the nontumorous lung. The quantity of KGF mRNA in the tumor tissue was twice that of the nontumorous lung. Moreover, there was dysregulation of FGFR2IIIb transcription in the tumor. According to these findings, we expect overexpression of FGFR2IIIb to play an important role in causing tumor. Because FGFR is suspected to be connected with lung carcinoma, we also treat similar tumorigenesis via FGFR as carcinoma; complete resection of adenoma might be indicated.

CT urography in the urinary bladder: To compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter

Background Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. Purpose To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). Material and Methods Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDIvol) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. Results The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDIvol demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. Conclusion EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.

Magnetic Resonance Imaging of a Urethral Caruncle and the Pathologic Correlation: A Report of 3 Cases

A urethral caruncle is the most common disease of the urethra in postmenopausal women. A definitive diagnosis can usually be reached based on physical examination. Cross-sectional imaging is performed when malignant urethral tumor is suspected, such as a urethral carcinoma. No articles have discussed the detailed imaging of urethral caruncles. We present 3 patients with symptomatic urethral caruncles who underwent magnetic resonance imaging preoperatively.