Radiation Medicine

The aim of this study was to optimize a novel adaptive noise reduction filter based on patient body weight and to investigate its utility for improving the image quality of low-dose hepatic computed tomography (CT) scans. The tube current-time product was changed from 140 to 180 and from 60 to 100 mAs at standard-and low-dose CT, respectively, based on the body weights of 45 patients. Unenhanced and two-phase contrast-enhanced helical scans were obtained at the standard dose during the hepatic arterial and equilibrium phases. During the equilibrium phase, we obtained low-dose scans of the liver immediately after standard-dose scans. The low-dose CT images were postprocessed with the filter. Two radiologists visually evaluated artifacts in the liver parenchyma and its graininess, the sharpness of the liver contour, tumor conspicuity, homogeneity of the enhancement of the portal vein, and overall image quality. There was no statistically significant difference between standard and filtered low-dose images with respect to artifacts in the liver, the graininess of the liver parenchyma, tumor conspicuity, homogeneity of enhancement of the portal vein, or overall image quality. The adaptive noise reduction filter effectively reduced image noise. We confirmed the effectiveness of the filter by examining clinical hepatic images obtained at low-dose CT.

The aim of this study was to evaluate the efficacy of double arterial phase dynamic magnetic resonance imaging (MRI) with the sensitivity encoding technique (SENSE dynamic MRI) for detection of hypervascular hepatocellular carcinoma (HCC) in comparison with double arterial phase dynamic multidetector-row helical computed tomography (dynamic MDCT). A total of 28 patients with 66 hypervascular HCCs underwent both double arterial SENSE dynamic MRI and dynamic MDCT. The diagnosis of HCC was based on surgical resection (n = 7), biopsy (n = 10), or a combination of CT during arterial portography (CTAP), CT during hepatic arteriography (CTA), and/or the 6-month follow-up CT (n = 49). Based on alternative-free response receiving operating characteristic (ROC) analysis, the diagnostic performance for detecting HCC was compared between double arterial phase SENSE dynamic MRI and double arterial phase dynamic MDCT. The mean sensitivity, positive predictive value, and mean Az values for hypervascular HCCs were 72%, 80%, and 0.79, respectively, for SENSE dynamic MRI and 66%, 92%, and 0.78, respectively, for dynamic MDCT. The mean sensitivity for double arterial phase SENSE dynamic MRI was higher than that for double arterial phase dynamic MDCT, but the difference was not statistically significant. Double arterial phase SENSE dynamic MRI is as valuable as double arterial phase dynamic MDCT for detecting hypervascular HCCs.

This is the first report of percutaneous transluminal angioplasty (PTA) of an intracranial artery applying intravascular ultrasound virtual histology (IVUS-VH), which has been recently developed for tissue characterization of coronary artery plaque. We report a case of successful PTA and stenting for symptomatic intracranial vertebral artery stenosis using IVUS-VH.

Một người đàn ông 48 tuổi đã đến khám với cơn đau ngực dữ dội bắt đầu 2 giờ trước và có sự nâng ST trên điện tâm đồ. Chụp cắt lớp vi tính tim mạch (CT) đã được thực hiện bằng máy quét đa detec-tor 64 lát cắt (MDCT) để đánh giá hẹp động mạch vành sau 3 giờ kể từ khi khởi phát. Chụp mạch vành CT cho thấy không có hẹp đáng kể ở các động mạch vành, nhưng hình ảnh cơ tim CT ở thì tâm thu cho thấy chủ yếu là giảm tăng cường nội tâm mạc ở vách trước. Chụp CT tim kết hợp chụp mạch vành và hình ảnh cơ tim đã cho thấy giảm tăng cường cơ tim trong một trường hợp hội chứng vành cấp với các động mạch vành bình thường, có thể liên quan đến rối loạn vi mạch do cơn đau thắt ngực co thắt hoặc đau thắt ngực vi mạch.

We investigated the difference between measured and manufacturer's nominal source strength in a large sample of a single model of 125I seeds. Physical characteristics of single seed measurement by the well-type ionization chamber were also investigated to provide dosimetric data. A well-type ionization chamber with a single seed holder was used to measure source strength of all 1935 125I seeds implanted in the initial 28 patients in our hospital. Physical characteristics including linearity of readings for different integral time intervals, reproducibility, isotropy, and axial positional sensitivity were assessed. To calculate the source strength, the integral charge during 30 s was measured and converted to air kerma strength. The nominal activity stated by the manufacturer was compared with the measured value. Linearity, reproducibility, and isotropy of the well-type ionization chamber were within 0.2%. Measured source strength was on average 2.1% (range −7.6% to +7.2%), lower than the nominal value. Standard deviation of all measured seeds was 2.0%. The maximum difference between the measured and the manufacturer's nominal source strength in each patient was −3.7%. The standard deviation averaged 1.6%. The nominal source strength of the 125I seeds agreed well with the measured value. Our study can be helpful as guidance for individual 125I seed source strength measurement.

We present a case of retroperitoneal well-differentiated inflammatory liposarcoma that was extremely difficult to diagnose preoperatively. Computed tomography and magnetic resonance images showed a 5-cm homogeneous soft-tissue mass with a decreased apparent diffusion coefficient and without fat component in the retroperitoneum. Minimal fat stranding was detected around the mass. The preoperative working diagnosis was malignant lymphoma or inflammatory pseudotumor, whereas the final diagnosis after surgery was well-differentiated inflammatory liposarcoma. As a result, only a large component of lymphoid infiltration was recognized as a tumor preoperatively, and minimal fat stranding represented a component of lipoma-like liposarcoma. In this entity, a lipomatous component could easily be missed on radiologic imaging because of the conspicuity of lymphoid infiltration. We should consider the possibility of this variant when we evaluate a retroperitoneal tumor.

A 33-year-old man with bilateral popliteal artery entrapment syndrome (PAES) presented with right calf claudication. He underwent radiological studies including conventional arteriography, multidetector row CT (MDCT), and magnetic resonance imaging (MRI) of the lower extremities. He had been fine since birth and athletic in his school days. Axial tomographic images by MDCT and MRI at the popliteal fossa bilaterally showed an anomalous medial head of the gastrocnemius muscle between the popliteal artery and vein, resulting in right popliteal artery occlusion and leading to the diagnosis of bilateral PAES type II. MDCT or MR facilitates noninvasive computer-aided arteriography and is often utilized for screening patients with claudication for peripheral arterial diseases. However, axial tomograms are more essential for confirming PAES than arteriography, and radiologists should continue to look for possible abnormalities on popliteal fossa tomograms because early diagnosis of PAES allows better choices and outcomes of treatment.

Extrahepatic portal-systemic shunts cause portal-systemic encephalopathy. Direct communication between the inferior mesenteric vein (IMV) and the inferior vena cava (IVC) is a relatively rare pathway among the variety of portal-systemic shunts. This report describes a case of successful occlusion of an IMV-IVC shunt. Based on laboratory data and computed tomography findings, a 69-year-old woman with liver cirrhosis was diagnosed with portal-systemic encephalopathy due to a shunt between the IMV and the IVC. Her hepatic coma had not been adequately controlled by oral or intravenous pharmacotherapy. First, we placed a covered stent in the main trunk of the portal vein and the superior mesenteric vein (SMV) to block the SMV hepatofugal flow and splenic vein hepatopetal flow, but this therapy showed only a transient therapeutic effect due to recanalization. Next, we performed balloon-occluded retrograde transvenous obliteration (BRTO) of the portal-systemic shunt. After the BRTO, she has had no episodes of portal-systemic encephalopathy for 2 years.

The pulmonary artery (PA) is involved in most congenital heart diseases; and in these patients it is necessary to evaluate precisely the PA configuration and development. The accuracy of 16 multidetector row computed tomography (16-MDCT) in evaluating the central PA was evaluated. 16-MDCT and angiocardiography (ACG) were performed in 26 patients with various congenital heart diseases aged 7 days to 9 years (median 1.2 years). We reconstructed coronal oblique images along the long axis of the right and left PAs and measured the PA diameter and Nakata’s PA index, which were compared with those obtained by ACG. Correlations between PA diameters [R 2 = 0.80, standard error of the estimate (SEE) = 1.3, n = 52] and PA indices (R 2 = 0.81, SEE = 42, n = 26) obtained from coronal oblique images and ACG were excellent. Bland-Altman plots showed a mean ± SD difference of −0.3 ± 1.3 mm for the PA diameter and ±15.1 ± 41.5 for the PA index. 16-MDCT might be useful for evaluating the central PA in patients with congenital heart disease.

Total lymphoid irradiation is employed in the preparative regimens for allogeneic bone marrow and solid organ transplantation, solid organ transplant rejection, and chronic graft-versus-host disease. Linear accelerator-based radiotherapy, typically involving opposed anteroposterior and posteroanterior beams, has been commonly used; however, extended source-to-skin patient setup and/or field matching are required, and all organs within the beam coverage receive the entire prescribed dose. Megavoltage helical tomotherapy represents a technological advance in terms of both treatment delivery and patient positioning. The continuously rotating multileaf collimated fan beam allows highly conformal coverage of complex target geometries, in turn allowing avoidance of radiosensitive adjacent organs. In addition, the megavoltage computed tomographic scans allow potentially more accurate, targetbased setup verification. The present case report describes tomotherapy-based total lymphoid irradiation in an adult patient with late-onset cardiac transplant rejection. Treatment planning allowed dose minimization to the spinal cord, kidneys, intestinal compartment, and lungs. The patient tolerated treatment well without acute adverse effects, and he is now in early follow-up.