An Appreciation for the Rabbit Ladderlike Modeling of Radiation-induced Lung Injury with High-energy X-Ray.

BACKGROUND: To evaluate the utility of rabbit ladderlike model of radiation-induced lung injury (RILI) for the future investigation of computed tomography perfusion. METHODS: A total of 72 New Zealand rabbits were randomly divided into two groups: 36 rabbits in the test group were administered 25 Gy of single fractionated radiation to the whole lung of unilateral lung; 36 rabbits in the control group were sham-radiated. All rabbits were subsequently sacrificed at 1, 6, 12, 24, 48, 72 h, and 1, 2, 4, 8,1 6, 24 weeks after radiation, and then six specimens were extracted from the upper, middle and lower fields of the bilateral lungs. The pathological changes in these specimens were observed with light and electron microscopy; the expression of tumor necrosis factor-α (TNF-a) and transforming growth factor-ß1 (TGF-ß1) in local lung tissue was detected by immunohistochemistry. RESULTS: (1) Radiation-induced lung injury occurred in all rabbits in the test group. (2) Expression of TNF-a and TGF-ß1 at 1 h and 48 h after radiation, demonstrated a statistically significant difference between the test and control groups (each P < 0.05). (3) Evaluation by light microscopy demonstrated statistically significant differences between the two groups in the following parameters (each P < 0.05): thickness of alveolar wall, density of pulmonary interstitium area (1 h after radiation), number of fibroblasts and fibrocytes in interstitium (24 h after radiation). The test group metrics also correlated well with the time of postradiation. (4) Evaluation by electron microscopy demonstrated statistically significant differences in the relative amounts of collagen fibers at various time points postradiation in the test group (P < 0.005), with no significant differences in the control group (P > 0.05). At greater than 48 h postradiation the relative amount of collagen fibers in the test groups significantly differ from the control groups (each P < 0.05), correlating well with the time postradiation (r = 0.99318). CONCLUSIONS: A consistent and reliable rabbit model of RILI can be generated in gradient using 25 Gy of high-energy X-ray, which can simulate the development and evolution of RILI.

Practical value of intravenous urography combined with add-on CT in diagnosing ureteral abnormalities.

BACKGROUND: Intravenous urography (IVU) combined with add-on CT (IVU-CT) can help to provide more diagnostic information for determining the localization and nature of ureteral abnormalities with less irradiation dose. This study aimed to determine the value of IVU-CT for diagnosis of ureteral diseases, where IVU is insufficient to determine the diagnosis. METHODS: Two hundred and eighty patients underwent IVU for suspected ureteral disorders, which identified a definite diagnosis in 184 cases and was insufficient for definite diagnosis in 96 cases designated as indeterminate diagnosis. Subsequently 90 patients (six patients declined CT) with indeterminate diagnosis consented to undergo immediate or delayed helical CT scan. The CT data were transferred to the workstation for post-processing, and the cost and mean effective dose for each imaging method were calculated and compared indirectly. RESULTS: Of the 90 indeterminate diagnosis cases, diagnosis was determined in 86 cases by IVU-CT with a diagnostic accordance rate of 95.6%, while 184/280 (65.7%) had diagnosis determined by IVU alone. There was a significant difference between IVU and IVU-CT in the determination of the diagnosis of ureteral diseases (c(2) = 36.4, P < 0.05). The cost of IVU equals to 1/8 - 1/9 of that for CT urography (CTU), and the cost of IVU-CT is as much as 1/3 of CTU. CTU results in the highest mean effective dose, approximately nine times that for IVU and three times that for IVU-CT. CONCLUSION: IVU-CT provides valuable information for the localization and diagnosis of ureteral abnormalities and may be considered as an efficient, cost-effective and low-dose diagnostic technique in this setting.