[Radiologic staging of renal cell carcinoma]

Evaluation of the impact of organ-specific dose reduction on image quality in pediatric chest computed tomography

BACKGROUND

Organ-specific dose reduction significantly reduces the radiation exposure of radiosensitive organs.

OBJECTIVE

The purpose of this study was to assess the impact of a novel organ-specific dose reduction algorithm on image quality of pediatric chest CT.

MATERIALS AND METHODS

We included 28 children (mean age 10.9 ± 4.8 years, range 3-18 years) who had contrast-enhanced chest CT on a 128-row scanner. CT was performed at 100 kV using automated tube current modulation and a novel organ-specific dose-reduction algorithm (XCare™; Siemens, Forchheim, Germany). Seven children had a previous chest CT performed on a 64-row scanner at 100 kV without organ-specific dose reduction. Subjective image quality was assessed using a five-point scale (1-not diagnostic; 5-excellent). Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were assessed in the descending aorta.

RESULTS

Overall mean subjective image quality was 4.1 ± 0.6. In the subgroup of the seven children examined both with and without organ-specific dose reduction, subjective image quality was comparable (score 4.4 ± 0.5 with organ-specific dose reduction vs. 4.4 ± 0.7 without it; P > 0.05). There was no significant difference in mean signal-to-noise ratio and contrast-to-noise ratio with organ-specific dose reduction (38.3 ± 10.1 and 28.5 ± 8.7, respectively) and without the reduction (35.5 ± 8.5 and 26.5 ± 7.8, respectively) (P > 0.05). Volume computed tomography dose index (CTDIvol) and size-specific dose estimates did not differ significantly between acquisitions with the organ-specific dose reduction (1.7 ± 0.8 mGy) and without the reduction (1.7 ± 0.8 mGy) (P > 0.05).

CONCLUSION

Organ-specific dose reduction does not have an impact on image quality of pediatric chest CT and can therefore be used in clinical practice to reduce radiation dose of radiosensitive organs such as breast and thyroid gland.

Wertigkeit der Bildgebung für die Lymphknotenmetastasierung beim Nierenzell-, Blasen-, Prostata- und Peniskarzinom sowie dem Hodentumor

Computed tomography (CT) imaging is the standard method for the assessment of lymph node metastases in renal cell and testicular cancer. In bladder cancer and prostate cancer the results of CT are not convincing due to a large number of false-negative findings and the prognostic relevance of undetected metastases. For both entities recent studies revealed that MR lymphography using iron oxide particles allows the detection of small metastatic lymph nodes. For penile cancer reliable results for imaging of lymph node metastases do not exist. PET imaging using [(18)F]-fluorodeoxyglucose (FDG) is the modality of choice in therapy control of seminomas but has no defined value in other urological malignancies. PET with [(11)C] choline and [(11)C] acetate offers great potential in staging and restaging of prostate cancer. Further investigations are necessary to determine the role of these new methods.

[Preoperative radiologic evaluation of tumors of the renal parenchyma]

Renal cell carcinoma is frequently a matter of urological interest. In recent years there were significant improvements regarding the earlier diagnosis, more precise preoperative staging and appropriate therapy. One hundred patients (42-78 years old) with the preoperative diagnosis of renal cell carcinoma were analyzed. Preoperative radiological evaluation included: transabdominal ultrasound, intravenous urography, computer-assisted tomography, and angiography. In all patients after radical nephrectomy pathohistological diagnosis was established and patients with the confirmed renal cell carcinoma tumour staging was performed. All histological findings were compared with the preoperative results of radiological examinations. Reliability of all of them is separately determined. Our results confirmed that the most efficient method of preoperative staging was computer-assisted tomography (accuracy 93%). Diagnostic methods that were previously used like intravenous urography and angiography, were not useful for routine diagnostic purposes. Ultrasound is a precise but not an enough informative diagnostic tool (accuracy 87%). Combine used of both ultrasound and contrast computer-assisted tomography is cost-effective, and an enough precise combination for everyday use.