Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part II: Assessment of Radiologists' Preferences Using Dual Source CT

OBJECTIVE: To evaluate the impact of radiation dose and reconstruction algorithms on radiologists' preferences, and whether an iterative reconstruction in image space (IRIS) can be used for dose reduction in chest CT. MATERIALS AND METHODS: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying the dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from one tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Ten H-IRIS/F-IRIS, 10 H-FBP/H-IRIS, 40 F-FBP/F-IRIS and 40 F-FBP/H-IRIS pairs of each SDCT and LDCT were randomized. The preference for clinical usage was determined by two radiologists with a 5-point-scale system for the followings: noise, contrast, and sharpness of mediastinum and lung. RESULTS: Radiologists preferred IRIS over FBP images in the same radiation dose for the evaluation of the lungs in both SDCT (p = 0.035) and LDCT (p < 0.001). When comparing between H-IRIS and F-IRIS, decreased radiation resulted in decreased preference. Observers preferred H-IRIS over F-FBP for the lungs in both SDCT and LDCT, even with reduced radiation dose by half in IRIS image (p < 0.05). CONCLUSION: Radiologists' preference may be influenced by both radiation dose and reconstruction algorithm. According to our preliminary results, dose reduction at 50% with IRIS may be feasible for lung parenchymal evaluation.

Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT

OBJECTIVE: To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. MATERIALS AND METHODS: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. RESULTS: Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. CONCLUSION: IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.

Spontaneous Rupture of Adrenal Metastasis from Hepatocellular Carcinoma

Rupture of adrenal tumor from various primary origins is a rather rare event. We report here on a ruptured adrenal metastasis from hepatocellular carcinoma, and this ruptured metastasis was observed at the time of the initial diagnosis.

A Case of Congenital Single Ectopic Kidney in Pelvis of Patients with Proteinuria / 대한신장학회잡지

Congenital anomalies of the genitourinary tract are the most common organ system anomalies. Ectopic kidney in pelvis is a kidney located outside the renal fossa, failed migration of ureteral bud and developing metanephric blastema to the renal fossa and rare fusion anomaly of the kidneys characterized by the presence of a displaced, lobulated pelvic renal mass. Herein we report a rare case of a patient presenting with single kidney in pelvis, review literatures and discuss prognosis of this case.