Radiation medicine最新文献

Purpose: The aim of this study was to investigate the frequency of breast tumors and breast cancers with noncontrast spiral chest computed tomography (CT).

Material and methods: A clinical study was conducted to evaluate findings in the mammary region of 1008 consecutive patients with no mammary symptoms or signs who underwent noncontrast spiral CT of the chest from April 2003 to March 2006.

Results: Six cases of breast abnormality were detected among the 1008 women. Three were primary breast cancers, one was metastatic breast cancer, and two were benign tumors. All four breast cancer patients were over 70 years old. The characteristics of the tumor margins on CT scans corresponded to the mammography and ultrasonography findings. The mammographic background density ranged from inhomogeneous high-density breast to fatty breast. The detection rate of primary breast cancer by noncontrast spiral CT was 0.30%.

Conclusion: Noncontrast spiral chest CT occasionally detects nonsymptomatic breast cancers, especially in elderly patients.

Purpose: The aim of this study was to compare the efficacy of two contrast materials with moderate and high iodine concentrations for the depiction of pancreatic adenocarcinoma.

Materials and methods: A series of 107 patients with histologically proven pancreatic adenocarcinoma underwent helical computed tomography. A fixed dose of 100 ml of iopamidol 300 (mg I/ml) was administered to 50 patients (group A) and iopamidol 370 (mg I/ml) to 57 patients (group B) at the same injection rate (3 ml/s). Unenhanced helical scans and contrast-enhanced scans for three phases (30, 70, and 300 s after starting the infusion of contrast material) were obtained. We evaluated enhancement of the aorta, portal vein, hepatic parenchyma, pancreatic parenchyma, and pancreatic adenocarcinoma during each phase.

Results: During all phases, both aortic and pancreatic enhancement were significantly greater in group B than in group A (P<0.01). Enhancement of the portal vein and hepatic parenchyma was significantly greater at 70 and 300 s in group B than in group A (both P<0.01). Tumor-to-pancreas contrast was significantly greater in group B than in group A at both 30 s (P<0.01) and 70 s (P<0.05).

Conclusion: Administration of contrast material with a high iodine concentration is more effective for depicting pancreatic adenocarcinomas.

Purpose: Several studies on the dosimetric properties of unflattened photon beams have shown some advantages for radiotherapy. In this study, the effect of removing the flattening filter from an 18-MV photon beam was investigated using the Monte Carlo method.

Materials and methods: The 18-MV photon beam of an Elekta SL25 linear accelerator was simulated using the MCNP4C Monte Carlo (MC) code. Beam dosimetric features, including central axis absorbed doses, beam profiles, and photon energy spectra, were calculated for flattened and unflattened 18-MV photon beams.

Results: A 4.24-fold increase in the dose rate was seen for the unflattened beam with a field size of 10 x 10 cm(2). A decrease in the out-of-field dose up to 30% was seen for the unflattened beam. For the unflattened beam, photon energy spectra were softer, and the mean energies of the spectra were higher for a smaller field size.

Conclusion: Our study showed that the increase in dose rate and lower out-of-field dose can be possible advantages for an unflattened 18-MV beam.

We describe here a case of vulvar epithelioid sarcoma. Epithelioid sarcoma is a malignant appendicular skin tumor that is rarely of vulvar origin. Magnetic resonance imaging (MRI) revealed a solid mass with an ulcer-like lesion and multilobulated contour. To our knowledge, this is the first case of vulvar epithelioid sarcoma described in the MRI literature.

A 71-year-old man presented with cough and sputum for 12 months. Chest radiography showed a homogeneous opacity in the right lower lobe. Computed tomography (CT) showed a nodular opacity, 2 cm in diameter, in the posterior segment of the right lower lobe. Mild emphysematous changes were also seen. With the patient in a prone position, a 19-gauge 7.8-cm introducer was placed in the lesion during a single inspiratory breath-hold. A coaxial 20-gauge automated needle was inserted through the introducer using a biopsy gun. Although the patient did not complain of any symptoms, postbiopsy CT showed air in the left ventricle and ascending aorta. After 5 h of bed rest, we found weakness in his left lower extremity. He was transferred to a hyperbaric oxygen chamber and recovered the next day. Air embolism is a rare, potentially fatal complication of percutaneous lung biopsy. Although the true effect of hyperbaric oxygen therapy is controversial, knowledge regarding the prompt management of such cases may help radiologists who perform this procedure.

Purpose: 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.

Materials and methods: 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.

Results: 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.

Conclusion: 16-MDCT might be useful for evaluating the central PA in patients with congenital heart disease.

Purpose: The aim of this study was to evaluate the effectiveness of computed tomography (CT) findings in the diagnosis of mediastinitis after cardiovascular surgery with median sternotomy.

Material and methods: A total of 122 patients were divided into two groups: the early group (21 days after surgery). Among them, six patients were ultimately diagnosed with infectious mediastinitis. CT findings in each patient were evaluated. Mediastinal fluid collections or free gas bubbles were regarded as the primary findings of mediastinitis.

Results: In the early group, sensitivity and specificity of the primary CT findings were 100% and 39%, respectively. In the late group, the sensitivity was 100% and the specificity 85%. Mediastinal fluid collections were observed in all six patients with mediastinitis.

Conclusion: Mediastinal fluid collections or free gas bubbles are not specific during the early postoperative period. However, after 2 21 days, these observations could be indicative of mediastinitis.

An 82-year-old man with an asymptomatic left high-grade carotid stenosis was treated with carotid artery stenting (CAS) under distal protection. The procedure consisted with predilation with a 5 x 40 mm percutaneous transluminal angioplasty (PTA) balloon, deployment of a 10 x 20 mm self-expandable stent, post-dilation with a 7 x 20 mm PTA balloon, and aspiration of debris with 60 ml of blood. The cervical carotid angiogram immediately after deflation of the distal blocking balloon demonstrated a small in-stent filling defect of the contrast medium that protruded from the anterior wall of the carotid artery. The following cranial carotid angiogram showed abrupt occlusion of the left middle cerebral artery (MCA). Because the in-stent lesion had vanished in the repeat study after recognition of this embolic event, it was suggested that an embolus had been liberated from the in-stent lesion, reaching the left MCA and obliterating it. In this case, the embolus was speculated to originate in the ruptured plaque, which protruded into the stent through the cells of the device and became liberated into the bloodstream. Attention should be paid so as not to overlook any plaque protrusion, which may be seen subsequently as a cerebral embolism on the angiogram obtained immediately after CAS.

Purpose: Most traumatic deaths in Japan are due to nonpenetrating injuries, especially those that result from traffic accidents; however, the autopsy rate of traffic accident-related deaths is only about 5%. We investigated the diagnostic ability of postmortem computed tomography (PMCT) in cases of fatal trauma after traffic accidents.

Materials and methods: Our subjects were 78 subjects (59 males, 19 females; mean age 50 years, range 15-87 years) who were brought to our institution in cardiopulmonary arrest on arrival after traffic accidents and died despite resuscitation attempts. PMCT findings of damage to the head, neck, thorax, abdomen, and pelvis were classified into three grades according to the Abbreviated Injury Scale (AIS) severity: A: 1 (minor), 2 (moderate); B: 3 (serious), 4 (severe), 5 (critical); C: 6 (maximum).

Results: The percentage ratio of A/B/C in 78 head injuries was 32/60/8, in 41 neck injuries 83/5/12, in 76 thorax injuries 5/38/57, in 76 abdominal injuries 70/24/7, and in 76 pelvic injuries 79/21/0, respectively.

Conclusion: PMCT can detect or presume fatal trauma when diagnosing the cause of death after traffic accidents.

Purpose: The present study was performed to identify the theoretical background for optimal use of the bolus tracking system by analyzing the changes in the initial slope of the aortic time-enhancement curve (TEC).

Materials and methods: We calculated the contrast medium aortic arrival time (TAR), the time to reach the trigger threshold (effective TAR), the slope of the linear equation of the enhancement unit (enhancement rate), and the time to peak aortic enhancement from the TECs of the pharmacokinetic analysis and retrospective clinical study.

Results: In the pharmacokinetic analysis, the enhancement rate-simulated under conditions of injection duration 30 s and iodine load per body weight 500 mg/kg-was 27.1 HU/s. In the clinical study, the enhancement rate was 27.9 +/- 3.0 HU/s. A correlation was found between the TAR and the enhancement rate, indicating that enhancement rates decrease with increasing TAR. It took 22.7 +/- 0.5 s to reach maximum enhancement of the aorta from the trigger threshold of an increase of 100 HU and injection duration at 30 s.

Conclusion: We found that cardiac output differences are strongly dependent on the TAR and that most of the differences disappeared during the phase until effective TAR.