Koji Takahashi

CT pixel mapping in the diagnosis of small angiomyolipomas of the kidneys.

In six small renal angiomyolipomas (7–17 mm) the superiority of displaying the CT numbers of pixels within a lesion (pixel mapping) over the usual region of interest (ROI) measurement is described in the detection of small amounts of fat tissue. On precontrast 5 mm CT the ROI measurements were >0 in four cases whereas pixel maps revealed pixels with values <0 in six cases.

Venous Sac Embolization of Pulmonary Arteriovenous Malformation: Preliminary Experience Using Interlocking Detachable Coils

AbstractPurpose: To evaluate the indication and advantages of venous sac embolization of pulmonary arteriovenous malformations (PAVMs) using interlocking detachable coils (IDCs).n Methods: We performed percutaneous embolization in 12 PAVMs in four patients using IDCs, initially placed in the venous sac or at the feeding artery to prevent systemic migration of additional coils. We placed the IDCs in the venous sac in PAVMs with the following vascular architecture: the draining vein was larger than the feeding arteries and both vessels were interposed with the venous sac or there were short feeding arteries.n Results: Complete occlusion was achieved in all 12 PAVMs without significant complications. We deployed IDCs in the venous sac in eight PAVMs and in the feeding artery in four.n Conclusion: Venous sac embolization may be beneficial in PAVMs with large out-flow vessels or short feeding arteries. IDCs are suitable for this procedure.

Paravertebral neurinoma associated with aggressive intravertebral extension

Abstractu2002Neurinomas are relatively common benign tumors thought to arise from nerve sheath cells. Although intraosseous neurinomas may destroy the bone, extraosseous neurinomas with extensive destruction and invasion of bone are considered rare. We present two unusual cases of a benign extraosseous neurinoma that extensively invaded the vertebral body through the nutrient canal.

CT findings of pulmonary parenchyma in Takayasu arteritis

PURPOSEnOur goal was to describe the pulmonary parenchymal manifestations of Takayasu arteritis visualized on CT.nnnMETHODnWe assessed the CT findings for the pulmonary parenchyma in 25 patients with Takayasu arteritis and compared them with those visualized by pulmonary angiography (n = 20) and radionuclide perfusion scintigraphy (n = 19).nnnRESULTSnA review of the CT scans revealed a total of 33 low attenuation areas in the lung (11 patients), subpleural reticulolinear changes (12 patients), and pleural thickening (9 patients). The low attenuation areas were preferentially seen in patients with pulmonary arteritis and corresponded to pulmonary angiographic staining and scintigraphic perfusion defects. No significant correlation was found between other CT findings and pulmonary arteritis.nnnCONCLUSIONnThe findings suggest that pulmonary low attenuation areas observed on CT represent regional hypoperfusion due to pulmonary arteritis. We speculate that pulmonary thromboembolism may contribute to other CT findings for the pleura and adjacent lung.

The growing teratoma syndrome secondary to immature teratoma of the ovary.

Abstract.nThe growing teratoma syndrome (GTS) secondary to a testicular nonseminomatous germ cell tumor has been well described since the first case was reported in 1982. In addition, radiological findings of male GTS have also reported in several studies; however, its occurrence secondary to an ovarian germ cell tumor is extremely rare. We experienced a 5-year-old girl who had GTS secondary to immature teratoma of the right ovary. In this article we present radiological findings of female GTS with clinical and pathological correlation.

Solitary fibrous tumor of the pleura: Apparent diffusion coefficient (ADC) value and ADC map to predict malignant transformation

Solitary fibrous tumors (SFTs) of the pleura are rare soft‐tissue tumors that are presumed to be of mesenchymal origin. Most SFTs are histologically benign, but up to 20% of SFTs may be malignant. In addition, malignant transformation may occur within histologically benign SFTs, though it is rare. However, it is difficult to diagnose malignant SFTs of the pleura by means of conventional computed tomography and magnetic resonance imaging (MRI). In this article we present the first case of malignant SFT of the pleura in an 81‐year‐old man in which the apparent diffusion coefficient (ADC) value and ADC map based on diffusion‐weighted MRI were very useful for identifying malignant transformation. J. Magn. Reson. Imaging 2007;26:155–158.

Acute rhabdomyolysis of the soleus muscle induced by a lightning strike: magnetic resonance and scintigraphic findings.

Among natural disasters, a lightning strike is a rare but potentially life-threatening phenomenon. If victims survive a cardiac arrest due to instantaneous passage of an exceptionally high voltage electric charge through the whole body, they may be afflicted with various complications such as muscle necrosis resulting in acute renal failure. In this article, we report a case of a 54-year-old man with acute rhabdomyolysis of the left soleus muscle associated with a lightning strike. T2-weighted and short-tau inversion recovery MR images showed a high signal intensity in the left soleus muscle. A whole-body bone scintigram showed abnormal uptakes in the left soleus muscle and the dorsal aspect of the left foot. MR and scintigraphic evaluations were very useful in depicting the site and extent of muscle damage. Since the patient showed a surprisingly high level of serum creatine kinase, the added information was very valuable for determining the patient’s management.

Mediastinal lymphatic drainage from pulmonary lobe based on CT observations of histoplasmosis: implications for minimal N2 disease of non-small-cell lung cancer

PurposeThe aim of this study was to assess mediastinal lymphatic drainage patterns from each pulmonary lobe using computed tomographic (CT) observations of calcified primary complex pulmonary histoplasmosis.Materials and methodsWe assessed 400 CT studies of patients with primary complex histoplasmosis consisting of a single lobe pulmonary lesion and mediastinal nodal disease. We assessed the distribution of mediastinal nodal involvement depending on pulmonary lobes for the total number of involved nodes, the number with single-station involvement (which suggests the initial site of involvement), and the number with skip involvement which suggests direct drainage to the mediastinum.ResultsThe most commonly involved mediastinal nodal stations from the right upper lobe, left upper lobe, and left lower lobe were the right lower paratracheal node (97%, 74/76), the subaortic node (72%, 49/68), and the left pulmonary ligament node (61%, 66/108), respectively. These nodes were the most common site of skip involvement in each lobe. In the right lower lobe and middle lobe, the subcarinal node was most commonly involved: 62% (65/105) and 81% (35/43), respectively. By contrast, skip involvement was uncommon in the drainage to this node.ConclusionOur data show a predictable pattern of lobar lymphatic drainage to the mediastinum. This may have implications on the minimal N2 disease of non-small-cell lung cancer.

Intraarterial digital subtraction angiography in detection of hepatocellular carcinoma

To evaluate the usefulness of intraarterial digital subtraction angiography (IADSA) in hepatocellular carcinoma, IADSA was prospectively performed, combined with conventional film-screen angiography, in 40 patients in whom the tumor was histologically proven or highly suspected. Of the 16 main tumors less than 2 cm, IADSA detected 7 that were missed by film-screen angiography; 6 of these were less than 1 cm in size. With other diagnostic modalities including ultrasound; routine CT study, and CT after intraarterial Lipiodol injection, the detection rate of these tumors was low. IADSAs contribution is important in the detection of small hepatocellular carcinomas.

Determination of Detection Efficiency Curve for a Gas Monitor with a Built-in Germanium Detector

Calibration techniques for a gas monitor with a built-in germanium detector were studied. The peak-detection efficiencies were precisely determined with some calibration gases. In order to obtain more reliable efficiency curves from the limited data of calibration gases, an interpolation technique using a multi-γ point source was applied. And also, the feasibility of simple calibration with the point source located at an appropriate single position was discussed. As a result, the efficiencies obtained with the calibration gases show good agreement with the efficiency curves derived by the interpolation technique. The efficiencies also agreed with efficiency curves determined by the simple calibration within an error of 4%.