Imaging of Solid Kidney Tumours in Children

Magnetic resonance urography in pediatric urology

PURPOSE OF REVIEW

Magnetic resonance urography (MRU) has emerged as a powerful diagnostic tool in the evaluation of the pediatric genitourinary tract. The purpose of this review is to familiarize the reader with the basic techniques, strengths and limitations, as well as the current and potential future applications of MRU in pediatric urology.

RECENT FINDINGS

MRU can provide detailed anatomical information and assess renal function and drainage in a single study. MRU does not employ ionizing radiation and may be utilized in patients with iodine-based contrast allergy or impaired renal function. MRU has been most often applied to the evaluation of hydronephrosis and provides valuable insight into a wide range of obstructive uropathies. MRU was shown to be superior to renal scintigraphy for the diagnosis of pyelonephritis and renal scarring. The use of MRU for the assessment of urolithiasis and vesicoureteral reflux is limited and technical refinements are required. Potential future applications include fetal MRU, virtual endoscopy, and MRU-guided procedures. The development of new contrast agents and new image-processing software will further enhance the diagnostic potential of MRU in pediatric urology.

SUMMARY

MRU is currently thought of as a problem-solving tool to define anatomy and function when conventional methods fall short. This technique is likely to emerge as the imaging modality of choice for children with complex genitourinary pathology.

Radiology–Pathology Conference: rhabdoid tumor of the kidney

Rhabdoid tumor of the kidney (RTK) is a rare pediatric malignancy. Its imaging features by ultrasound and CT have been well described; however, to our knowledge, there are only a handful of case reports that describe the MR appearance of rhabdoid tumor. We report the MR appearance of a RTK in an 18-month-old boy, review the literature on its imaging features, and discuss the differential diagnosis of solid renal tumors in children.

Imaging of neuroblastoma and Wilms' tumor

Neuroblastoma and Wilms' tumor are the most common noncentral nervous system solid tumors in children. Imaging plays a crucial role in the evaluation of the primary tumor and regional and metastatic disease. There is a growing body of literature supporting the use of MRI as the technique of choice for the evaluation of local and regional disease in children with suspected neuroblastoma; however, in children with suspected Wilms' tumor, MRI will likely continue to play a role as a problem-solver when the results of CT are equivocal or indeterminant.

PET FDG studies of Wilms tumors

PURPOSE

Wilms tumor is the most common renal neoplasm in children. The diagnosis is usually suggested by anatomic imaging and established by biopsy or resection. The principal roles of functional imaging have been the search for skeletal metastases and evaluation of renal function. We hypothesized that, like many tumors, Wilms tumors could concentrate 18F-FDG and that evaluation of the metabolic activity of these neoplasms might prove clinically useful.

MATERIALS AND METHODS

Three patients with known or suspected Wilms tumors underwent positron emission tomography (PET) with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) scanning (four scans). A patient with a single Wilms tumor was studied once at the time of diagnosis. The two patients with bilateral Wilms tumors were studied during therapy.

RESULTS

Uptake of FDG was present in the Wilms tumor studied at diagnosis, and in one of the tumors in each of the patients with bilateral disease studied during therapy. In all three cases, the results of the PET scans influenced therapeutic decisions.

CONCLUSION

PET FDG scanning may be useful for the management of selected patients with Wilms tumors.