Prospectively versus retrospectively ECG-gated 256-slice CT angiography to assess coronary artery bypass grafts--comparison of image quality and radiation dose.

OBJECTIVE: In this retrospective non-randomized cohort study, the image quality and radiation dose were compared between prospectively electrocardiogram (ECG)-gated axial (PGA) and retrospectively ECG-gated helical (RGH) techniques for the assessment of coronary artery bypass grafts using 256-slice CT. METHODS: We studied 124 grafts with 577 segments in 64 patients with a heart rate (HR) <85 bpm who underwent CT coronary angiography (CTCA); 34 patients with RGH-CTCA and 30 patients with PGA-CTCA. The image quality of the bypass grafts was assessed by a 5-point scale (1 = excellent to 5 = non-diagnostic) for each segment (proximal anastomosis, proximal, middle, distal course of graft body, and distal anastomosis). Other objective image quality indices such as noise, signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) were assessed. Radiation doses were also compared. RESULTS: Patient characteristics of the two groups were well matched except HR. The HR of the PGA group was lower than that of the RGH group (62.0 ± 5.0 vs. 65.7 ± 7.4). For both groups, over 90% of segments received excellent or good image quality scores and none was non-evaluative. The image quality generally degraded as graft segment approached to distal anastomosis regardless of techniques and graft types. Image quality scores of the PGA group were better than those of the RGH group (1.51 ± 0.53 vs. 1.73 ± 0.62; p<0.001). There was no significantly difference of objective image quality between two techniques, and the effective radiation dose was significantly lower in the PGA group (7.0 ± 1.2 mSv) than that of the RGH group (20.0 ± 4.6 mSv) (p<0.001), with a 65.0% dose reduction. CONCLUSIONS: Following bypass surgery, 256-slice PGA-CTCA is superior to RGH-CTCA in limiting the radiation dose and obtaining better image quality for bypass grafts.

Unusual imaging features of completely isolated enteric duplication in a child.

We report a case of completely isolated enteric duplication in an 18-month-old boy in whom US revealed a reniform abdominal mass with a pseudokidney sign that had no connection to adjacent organs. Distinctive histopathological changes of the duplication account for these unusual imaging features. Our case represents a diagnostic challenge in this rare entity. To our knowledge, this is a unique case.

Terminal ileum perforation from a misplaced percutaneous suprapubic cystostomy.

Iatrogenic bowel injury is a recognized complication of percutaneous suprapubic cystostomy. In the present report, we report an unusual case of small bowel perforation caused by a misplacement of suprapubic catheter into terminal ileum. For safe placement of a suprapubic catheter, the patients must have an adequately distended bladder and be placed in Trendelenburg position that allows safe extraperitoneal puncture of the bladder.

Disseminated cryptococcosis with pulmonary and marrow involvement mimicking radiological features of malignancy.

The most commonly involved sites of cryptococcosis are the lungs and the central nervous system. Cryptococcal osteomyelitis is a rare complication of disseminated cryptococcosis, and the vertebraes are the most common site of this infection. The most common underlying disease is sarcoidosis, followed by tuberculosis and previous steroid therapy. Conservative treatment alone or treatment with a combination of the medical and surgical curettage is successful in most cases. We report a case of cryptococcal osteomyelitis in a 63-year-old immunocompetent male who presented with lower back pain over the sacral region for several years. Radiologic studies showed a pulmonary mass and a radiolytic lesion involving the left ischial bone, which mimicked pulmonary malignancy with bone metastasis. Biopsy of the lung mass and the bone lesion revealed abundant cryptococcal organisms, and cryptococcal osteomyelitis was diagnosed.

Utility of source images of three-dimensional time-of-flight magnetic resonance angiography in the diagnosis of indirect carotid-cavernous sinus fistulas.

BACKGROUND: We sought to assess the relative contribution of magnetic resonance imaging (MRI), maximum intensity projection (MIP), and source images of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) to the diagnosis of indirect (dural) carotid-cavernous sinus fistulas (CCFs). METHODS: MRI and 3D TOF MRA were obtained in eight consecutive patients with indirect CCFs confirmed by conventional catheter angiography. Two radiologists masked to the angiographic results reviewed images retrospectively to evaluate the efficacy of MRI and 3D TOF MRA source and MIP images in the diagnosis of CCF. RESULTS: MRI disclosed CCF in five of eight cases; MIP images of TOF MRA disclosed CCF in four cases; source images of TOF MRA disclosed all eight CCF cases. CONCLUSIONS: The MRA source images are indispensable for a confirmatory diagnosis of indirect (dural) CCF. Underdiagnosis may occur by relying on MRI or 3D TOF MIP images alone.

Radiation exposure during transmission measurements: comparison between CT- and germanium-based techniques with a current PET scanner.

In positron emission tomographic (PET) scanning, transmission measurements for attenuation correction are commonly performed by using external germanium-68 rod sources. Recently, combined PET and computed tomographic (CT) scanners have been developed in which the CT data can be used for both anatomical-metabolic image formation and attenuation correction of the PET data. The purpose of this study was to evaluate the difference between germanium- and CT-based transmission scanning in terms of their radiation doses by using the same measurement technique and to compare the doses that patients receive during brain, cardiac and whole-body scans. Measurement of absorbed doses to organs was conducted by using a Rando Alderson phantom with thermoluminescent dosimeters. Effective doses were calculated according to the guidelines in the International Commission on Radiation Protection Publication Number 60. Compared with radionuclide doses used in routine 2-[fluorine-18]-fluoro-2-deoxy-D-glucose PET imaging, doses absorbed during germanium-based transmission scans were almost negligible. On the other hand, absorbed doses from CT-based transmission scans were significantly higher, particularly with a whole-body scanning protocol. Effective doses were 8.81 mSv in the high-speed mode and 18.97 mSv in the high-quality mode for whole-body CT-based transmission scans. These measurements revealed that the doses received by a patient during CT-based transmission scanning are more than those received in a typical PET examination. Therefore, the radiation doses represent a limitation to the generalised use of CT-based transmission measurements with current PET/CT scanner systems.

Usefulness of three-dimensional electron beam computed tomography for evaluating tracheobronchial anomalies in children with congenital heart disease.

This study was undertaken to delineate tracheobronchial anomalies associated with congenital heart disease. From June 1995 to December 2000, 1,245 children with congenital heart disease underwent cardiac electron beam computed tomography with 3-dimensional reconstruction on an independent workstation. Tracheobronchial anomalies are strongly associated with congenital heart disease and accompanying tracheal stenosis is not uncommon. With 3-dimensional reconstruction, electron beam computed tomography provided excellent anatomic definition of the central tracheobronchial abnormalities.

Adrenal gland volume after spinal cord injury.

OBJECTIVE: Spinal cord injury in adult men may result in hypothalamic-pituitary-adrenal axis dysfunction. Atrophy of adrenal glands was speculated in these patients. This study was undertaken to clarify the functional-anatomic correlation between adrenal volume and body surface area in subjects with spinal cord injury with impaired adrenal reserve. DESIGN: Twenty male subjects with chronic spinal cord injury with impaired adrenal reserve were identified by adrenocorticotropic hormone stimulation test from a group of 42 subjects. All subjects with spinal cord injury and healthy volunteers underwent computed tomographic imaging with contiguous 3-mm section over adrenal glands for volumetric measurements. Ten pairs of subjects with spinal cord injury and controls with matched height and weight were included in the statistical analysis. RESULTS: Significantly increased relative adrenal volumes were noted among subjects with chronic spinal cord injury and impaired adrenal reserve as compared with the body weight-matched and height-matched control group. CONCLUSIONS: Increased relative adrenal volumes were found after chronic spinal cord injury. Hyperplasia of the zona glomerulosa may be the cause of increased relative adrenal volume after chronic spinal cord injury.