Assessment of patient dose and image quality for cardiac CT with breast shields.

Breast shielding can reduce dose to the female breast, a radiosensitive organ receiving significant radiation during computed tomography (CT) chest examinations, particularly in cardiac CT, where Electrocardiogram dose modulation currently precludes the use of radial dose modulation to reduce breast dose. However, breast shields may produce artefacts affecting interpretation of coronary arteries. This study explores the dose savings and the effect of breast shields on image quality with torso and CT dose index body phantoms and an organ dose calculator. Change in dose calculated: 53-63 % (female breast), 82-85 % (lung), 79-84 % (oesophagus) and 76-80 % (effective dose) with larger dose reductions at lower kVp. Image quality is preserved when breast shields are placed after the scout no closer than 10 mm from the skin. Therefore, breast shields can be used in cardiac CT to reduce breast dose without compromising image quality. Revised conversion factors for dose length product to effective dose are suggested for cardiac CT without and with breast shields.

Unusual presentation of perirenal lung metastases.

Lung cancer is not commonly known to metastasize to the perirenal space, with only five such cases previously published. We present an unusual case of perirenal lung metastases manifesting as diffuse perinephric stranding which to our knowledge has not been described before.

Imaging of groin masses: inguinal anatomy and pathologic conditions revisited.

The groin region is subdivided into two distinct anatomic areas: the inguinal canal and the femoral triangle. A series of cross-sectional imaging cases illustrate that a good understanding of the local anatomic characteristics of the groin allows confident characterization of groin pathologic conditions. Such conditions can be classified into five major groups: congenital abnormalities, noncongenital hernias, vascular conditions, infectious or inflammatory processes, and neoplasms. Congenital entities include hernias, cysts, undescended testis, and retractile testes. Ultrasound (US) is useful in depicting these conditions. In the second group, noncongenital hernias, US allows visualization of bowel loops in peristalsis within the hernia. Herniography, computed tomography (CT), and magnetic resonance (MR) imaging are also helpful in diagnosis. Among vascular conditions, false aneurysms may be detected from the turbulent flow through the tract at Doppler US. The characteristic venous flow of varicoceles is best diagnosed with US during the Valsalva maneuver. Infectious or inflammatory conditions include, among others, hematomas, which appear hyperattenuating at CT and have variable appearances, depending on the age of the blood products, at MR imaging. The origins of neoplasms may be assessed at CT and MR imaging, although appearances of solid tumors are relatively nonspecific.

Spiral versus electron-beam CT for coronary artery calcium scoring.

PURPOSE: To determine differences in coronary artery calcium detection, quantification, and reproducibility, as measured at electron-beam computed tomography (CT) and subsecond spiral CT with retrospective electrocardiogram gating in an asymptomatic adult population. MATERIALS AND METHODS: Seventy subjects asymptomatic for coronary heart disease underwent both electron-beam CT and subsecond spiral CT. In all subjects, two images each were obtained with both scanners. Two experienced readers using three different algorithms scored each of the four scans: one score for the electron-beam CT images and two scores for the spiral CT images. RESULTS: With a 130-HU threshold for the quantification of calcium, there were no significant differences in interscan and interobserver variation in calcium scores between the electron-beam CT and spiral CT images. There was greater interobserver (P <.001) and interscan (P <.03) variation in scores when a 90-HU threshold was used for spiral CT images. With a 130-HU threshold, when calcium scores were used for clinical risk stratification, there was a significant difference between the results obtained with electron-beam CT and those obtained with spiral CT (P <.05). CONCLUSION: Spiral CT has not yet proved to be a feasible alternative to electron-beam CT for coronary artery calcium quantification. There are systematic differences between calcium scores obtained with single-detector array subsecond spiral CT and those obtained with electron-beam CT.