1 Answer B. The images demonstrate dilatation of the left renal pelvis and calyces without ureterectasis. The right kidney is normal. These findings are often seen in a UPJ obstruction. However, vesicoureteral reflux should be excluded as the cause of the left-sided pelvicaliectasis, which is why a VCUG would be the next best step in management. Note that in a male, a VCUG would also help exclude a posterior urethral valve, which can cause bladder outlet obstruction and pelvicaliectasis. Plain radiographs of the abdomen will not be helpful in determining the cause of the pelvicaliectasis, and a CT scan of the abdomen and pelvis will also not be helpful in determining whether vesicoureteral reflux is the cause of the pelvicaliectasis. Both of these exams would needlessly expose the child to ionizing radiation. Although a testicular ultrasound does not utilize ionizing information, it would not give us any information about the cause for the pelvicaliectasis.

References: Blickman JG, Parker BR, Barnes PD. Pediatric radiology: the requisites, 3rd ed. Philadelphia, PA: Elsevier/Saunders, 2009.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

2 Answer A. The image from the VCUG examination fails to demonstrate vesicoureteral reflux, which can now be excluded as a cause for the leftsided pelvicaliectasis. So, we now know that there is a UPJ obstruction and a functional and dynamic imaging study should be ordered to determine whether surgical intervention will be necessary. A Tc-99m MAG-3 study should provide that information as it is a dynamic test that evaluates uptake and clearance of radiotracer by the kidneys as well as drainage of radiotracer into the ureters and bladder. None of the other tests will yield this information as they are not functional exams. A Tc-99m DMSA scan is a functional but not a dynamic study used to evaluate for cortical scarring and/or pyelonephritis. This exam might be helpful if the patient had vesicoureteral reflux, especially if it was accompanied by a UTI, but the VCUG was negative for reflux. A CT scan is not a dynamic exam. A right upper quadrant ultrasound also would not be helpful but could evaluate the gray-scale appearance of the right kidney. However, the right kidney was normal on the initial ultrasound exam.

References: Blickman JG, Parker BR, Barnes PD. Pediatric radiology: the requisites, 3rd ed. Philadelphia, PA: Elsevier/Saunders, 2009.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Fernbach SK, Feinstein KA, Schmidt MB. Pediatric voiding cystourethrography: a pictorial guide. Radiographics 2000;20(1):155-168; discussion 168-171.

3 Answer C. The image demonstrated is a renogram of the left kidney obtained after Lasix administration. The time of maximum activity (Tmax) is approximately 2.5 minutes, and the time of ½ maximum activity (T1/2max) is around 10.5 minutes. Therefore, the time from max to half max is about 8 minutes. In addition, there is significant downsloping of the curve consistent with a good response to Lasix.

Dilated collecting systems secondary to fixed or functional obstruction may produce continuously rising renogram curves before Lasix administration with little to no evidence of excretion or downsloping. After Lasix administration, the curve should be inspected for change. In dilated, nonobstructed systems, Lasix causes increased urine flow through the collecting system, which washes out the initial increase in activity and causes a decline of the excretion similar to this case. In the case of significant mechanical obstruction, there is very little decrease in the renal collecting system activity after administration of Lasix because of the narrowed and fixed lumen of the ureter. The rising renogram curve is changed little or is unaffected. These patients are often treated with a surgical pyeloplasty.

Reference: Mettler FA, Guiberteau MJ. Essentials of nuclear medicine, 6th ed. Philadelphia PA: Saunders Elsevier, 2012.

4 Answer B. The images demonstrate multiple noncommunicating cysts throughout the right kidney without a dilated renal pelvis. These findings are consistent with a multicystic dysplastic kidney. These lesions are associated with a contralateral UPJ obstruction in 7% to 27% of cases. There is some controversy whether or not these lesions have a risk of malignant transformation and because of this are usually followed by serial ultrasound exams. These lesions usually slowly decrease in size over time, and often, the remaining residual dysplastic kidney will no longer be visualized by imaging techniques. There is typically no radiotracer uptake by the affected kidney on a MAG-3 scan as there is no function. Because of this, the contralateral kidney will often be enlarged in size because of compensatory hypertrophy.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

5 Answer C. The images are coronal images from an contrast-enhanced CT scan of the abdomen and pelvis, which demonstrate multiple round foci of low attenuation compatible with renal cysts. The cysts appear to be a few centimeters in size. These findings are most compatible with autosomal dominant polycystic kidney disease (ADPKD). This can be distinguished by the age of the patient as well as the size of the cysts. Although autosomal recessive polycystic kidney disease (ARPKD) can give renal macrocysts, most cysts are usually small and in the range of 1 to 2 mm. There is an association of ARPKD with congenital hepatic fibrosis. In addition, ARPKD usually affects children in the first decade of life, whereas ADPKD usually affects patients in during the teenage to adult years. ADPKD is associated with berry aneurysms in approximately 10% of cases.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

6 Answer C. The abdominal plain film demonstrates a soft tissue density in the left hemiabdomen, which is concerning for a mass lesion (arrows). The next best test would be a cross-sectional imaging study to try and identify the mass and its origin. An abdominal ultrasound would be the best way to accomplish this in an inexpensive way without the use of ionizing radiation. A Tc-99m MAG-3 scan may show some renal abnormality, but it would not be the best way to visualize the suspected tumor. An I-123 MIBG scan would be helpful to see if the tumor is MIBG avid as in cases of tumors of neural crest origin such as neuroblastomas, which often originate in the adrenal region. However, at this point, we do not know the origin of the tumor. A VCUG would not be helpful to visualize the tumor as this test is usually performed to look for vesicoureteral reflux.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

7 Answer D. The ultrasound images demonstrate a heterogeneous mass in the region of the left kidney labeled as “LK” on the ultrasound images. It is still difficult to determine the origin of the tumor. Therefore, an alternative cross-sectional imaging modality is needed to define the origin and extent of the mass lesion. An MRI of the abdomen and pelvis with and without intravenous contrast would be a good way to further image the tumor without the use of ionizing radiation although the child would likely need to be sedated for the exam. For similar reasons explained in the explanation to Question 6, neither an I-123 MIBG scan, Tc-99m MAG-3 scan, nor a VCUG scan would be helpful. A CT scan of the abdomen would also be appropriate to further image the tumor but would require the use of ionizing radiation.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Son J, Lee EY, Restrepo R, et al. Focal renal lesions in pediatric patients. Am J Roentgenol 2012;199(6):W668-W682.

8 Answer C. Figure A is an axial T2-weighted image with fat saturation from an MR exam, which demonstrates a heterogeneous mass arising from the left kidney. A “claw sign” of renal tissue is seen medially (arrows). Figure B is a coronal image from a T1-weighted image with fat saturation and after contrast enhancement, which again demonstrates a heterogeneous lesion arising from the left kidney with a medial “claw sign” of renal parenchyma (arrows). Given the patient’s age group, a Wilms tumor would be the most likely tumor. Renal cell carcinoma occurs in older children and the adult population, and mesoblastic nephroma, a generally benign tumor, usually occurs in neonates. Neuroblastomas often arise from the adrenals.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Son J, Lee EY, Restrepo R, et al. Focal renal lesions in pediatric patients. Am J Roentgenol 2012;199(6):W668-W682.

9 Answer A. When evaluating a suspected Wilms tumor, it is important to document the following features: lymph node involvement, liver and lung metastasis, involvement of the contralateral tumor by a synchronous tumor, the anatomic distribution of the intrarenal tumor, involvement of the renal vein or inferior vena cava, and the path of the ureters in relation to the mass. Therefore, a CT scan of the chest would be indicated. A VCUG would not be helpful to evaluate any of the above features. An I-123 MIBG scan would be helpful to evaluate the extent of a neuroblastoma but is not indicated for a Wilms tumor. Because osseous metastatic disease is rare in Wilms tumor, bone scans are not required as part of the workup.

Reference: Carroll WL, Finlay JL. Cancer in children and adolescents. Boston, MA: Jones and Bartlett Publishers, 2010.

10 Answer B. The current overall survival for Wilms tumor is slightly >90%, but this does vary with extent of disease and histology. There are both favorable and unfavorable histologic subtypes. Invasion of the renal vein and inferior vena cava occurs commonly in Wilms tumor. Nephroblastomatosis is a rare entity that is related to the persistence of nephrogenic rests within the renal parenchyma. These nephrogenic rests are the precursors of Wilms tumors.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

11 Answer D. Renal medullary carcinoma is a rare aggressive renal malignancy that is strongly associated with sickle cell (SC) trait or hemoglobin SC disease. With a peak age of presentation at 20 years, this neoplasm arises predominantly from the renal medulla. None of the other tumors listed are associated with sickle cell trait.

Reference: Son J, Lee EY, Restrepo R, et al. Focal renal lesions in pediatric patients. Am J Roentgenol 2012;199(6):W668-W682.

12 Answer D. The ultrasound images demonstrate a hypoechoic oval avascular mass located between the testicle and epididymis (arrows). This is consistent with a torsed appendix testis. Note that torsed testicular appendages can be of varying echogenicity. Testicular appendageal torsion is a common cause of an acute scrotum in prepubertal boys. The appendages are normal remnants of embryonic tissue and are usually located adjacent to the superior testicle or epididymal head. Testicular appendages are more prevalent than epididymal appendages; however, the distinction is often difficult to make and is not important clinically. Additional findings may include scrotal edema and reactive hydroceles. Color Doppler may show hyperemia surrounding the torsed appendage. Treatment involves conservative management.

Reference: Sung EK, Setty BN, Castro-Aragon I. Sonography of the pediatric scrotum: emphasis on the Ts-torsion, trauma, and tumors. Am J Roentgenol 2012;198(5):996-1003.

13 Answer A. The ultrasound images demonstrate a lesion within the left ovary that contains hyperechoic foci, some of which appear to shadow. Thus, this lesion may contain fat and/or calcium. The lesion itself appears avascular, but there does appear to be flow in the surrounding left ovarian parenchyma. A cross-sectional imaging modality is necessary to better define and characterize the lesion. An MRI would be preferred over CT because of the lack of ionizing radiation and its ability to characterize sonographically indeterminate adnexal masses of uncertain origin and solid or complex cystic content. Although this lesion may contain calcium, it appears to arise from the left ovary and therefore is extremely unlikely to be a neuroblastoma, so an MIBG scan would not be indicated.

Reference: Adusumilli S, Hussain HK, Caoili EM, et al. MRI of sonographically indeterminate adnexal masses. Am J Roentgenol 2006;187(3):732-740.

14 Answer C. The CT scan demonstrates a lesion arising from the left ovary, which contains fat and calcium as well as solid components. These findings are consistent with an ovarian teratoma. These lesions lead to torsion of the involved ovary in approximately 16% of cases. Approximately 1% to 4% of ovarian teratomas rupture, and approximately 1% to 2% undergo malignant transformation. It is common to see a soft tissue protuberance in a mature cystic teratoma; this is known as a Rokitansky nodule or dermoid plug. Although this protuberance may be partly solid and consist of diverse tissues, benign teratomas never show transmural growth of the protuberance. Contrast enhancement of a Rokitansky nodule raises the possibility of malignant transformation, although this finding does not always necessarily indicate malignancy.

Reference: Park SB, Kim JK, Kim KR, et al. Imaging findings of complications and unusual manifestations of ovarian teratomas. Radiographics 2008;28(4):969-983.

15 Answer B. The images demonstrate bilateral pelvicaliectasis. In addition, the bladder wall appears irregularly thickened even for a partially contracted bladder. In a male, these findings raise the possibility of bladder outlet obstruction from a posterior urethral valve. A VCUG exam will evaluate the urethra as well as test for vesicoureteral reflux. None of the other tests will be able to determine if there is a posterior urethral valve. Although the patient will require surgery if there is a posterior urethral valve, it is necessary to determine if the patient has a posterior urethral valve prior to surgical intervention.

Reference: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

16 Answer B. The images demonstrate marked dilatation of the posterior urethra (long arrows) with a normal appearance of the anterior urethra (short arrows). These findings are consistent with a posterior urethral valve, which is found exclusively in males. These lesions are treated surgically. In patients with posterior urethral valves (PUV), severe unilateral vesicoureteral reflux (VUR) is one of the three conditions associated with preservation of renal function. Others are urinary ascites or urinoma in newborns and large congenital bladder diverticula. These conditions most likely provide a pop-off mechanism preventing the development of high intravesical pressure. Only 5% of patients with PUV and an associated popoff mechanism will develop renal failure as opposed to 40% of patients with PUV without a protective factor.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Goodwin OI, Ayotunde OO. Posterior urethral valves with severe unilateral vesicoureteral reflux in a 3-year-old boy. Ann Ib Postgrad Med 2007;5(2):73-76.

17 Answer D. The ultrasound image demonstrates multiple bright echogenic nonshadowing foci throughout the testes. These findings are consistent with testicular microlithiasis. There is often no posterior acoustic shadowing because of the small size of the calcifications. It was initially reported that the risk of development of testicular neoplasms of those with this condition is between 18% and 75%. This led to recommendations for serial screening ultrasounds in patients with testicular microlithiasis to exclude development of neoplasm. However, more recent reports have shown that testicular microlithiasis is much more common than suspected, occurring in about 6% of males between 17 and 35 years of age and that the overwhelming majority of these patients will not develop malignancies. Some now advocate following these patients with physical examination rather than ultrasound. One recent paper stated that recommended follow-up depends on the ability of the child to cooperate and may include periodic US, periodic physical examination by the physician, and/or education of the patients to perform selfexamination of the scrotum.

Because this condition is not a urologic emergency, a stat urology consult would not be indicated. This condition is not associated with active infection, and therefore an MRI of the pelvis to look for a site of infection is not indicated. As stated earlier, this condition is more common than anticipated in the young male population and a metastatic workup is not indicated in the absence of other findings of neoplasm.

References: Cooper ML, Kaefer M, Fan R, et al. Testicular microlithiasis in children and associated testicular cancer. Radiology 2014;270(3):857-863.

Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

18 Answer B. The image is taken from a voiding cystourethrogram, which demonstrates bilateral vesicoureteral reflux. A “drooping lily” sign is seen on the right (arrows). This sign is identified in patients with a duplex collecting system. The drooping lily sign is due to inferior and lateral displacement of the lower pole moiety of a duplex kidney, rather than displacement of an entire kidney. An obstructed, poorly functioning upper pole moiety exerts a mass effect on the lower pole collecting system, which is responsible for the abnormal axis of the lower pole calices and which causes the droop of the lily. Because only the lower pole collecting system is opacified with intravenously administered contrast material, a decreased number of calices are depicted, as no calices extend cephalad from the renal pelvis. No drooping lily sign is seen in the left kidney, which has a single collecting system.

Reference: Callahan MJ. The drooping lily sign. Radiology 2001;219(1):226-228.

19 Answer D. In patients with complete ureteropelvic duplication, the ureteral orifice of the upper pole moiety inserts more medially and inferiorly than does the orifice of the lower pole ureter. The lower pole system is more prone to vesicoureteral reflux and UPJ obstruction. The upper pole moiety is more prone to obstruction secondary to a ureterocele. This is known as the Weigert-Meyer rule.

Reference: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

20 Answer A. The images demonstrate a large paravertebral mass, which is seen in the right lower portions of the thorax and upper retroperitoneum. There are internal calcifications seen on the CT scan (arrows). On the MR image, there is extension of the tumor into the right spinal canal (arrow). In a child of this age group, the most likely etiology of the lesion is a neurogenic tumor such as neuroblastoma (NB) or a ganglioneuroblastoma (GNB). In an older child, a ganglioneuroma (GN) could also be considered. I-123 MIBG is taken up by catecholamine-producing tumors such as NB, GNB, and GN. Although 90% to 95% of NB and GNB secrete catecholamines, only about 70% of NB and GNB are MIBG positive; one of the drawbacks of I-123 MIBG imaging is that a considerable minority of tumors (30%) are not MIBG avid.

Tc-99m MAG-3 scans are used to determine renal function and evaluate for possible obstruction. Tc-99m DMSA scans are used to evaluate for pyelonephritis or renal cortical scarring. There is no evidence of the tumor involving the kidneys. Gallium 67 scans are used to evaluate for sources of chronic infection. In addition, this radiotracer is also taken up by certain neoplasms such as non-Hodgkin lymphoma, Hodgkin disease, hepatoma, and melanoma. Gallium 67 scans are not useful to evaluate neuroblastoma.

References: Dähnert W. Radiology review manual, 6th ed. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2007.

Lonergan GJ, Schwab CM, Suarez ES, et al. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics 2002;22(4):911-934.

21 Answer B. The tumor seen on the CT and MR images is MIBG avid and therefore likely represents a neuroblastoma. Children who are diagnosed with these tumors at <1 year of age usually have a good prognosis. In these patients, the disease tends to spread to the liver and skin. Children who are diagnosed with neuroblastoma older than 1 year of age usually have a poor prognosis. In these patients, the disease tends to spread to the bone. Note that there is a special stage in the staging of neuroblastoma known as IV-S, which is given to patients who are diagnosed at less than a year of age with metastatic disease that is confined to the skin, liver, and bone marrow. Cortical bone involvement is not considered to be part of IV-S.

Expression of the N-Myc protein has been found to correlate with poor prognosis and aggressive tumor behavior in children older than 1 year. Other tumor features that influence prognosis include CD44, a glycoprotein on the surface of NB cells. Increased levels of CD44 correlate with a better prognosis. Elevated serum levels of ferritin indicate a worse prognosis.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Lonergan GJ, Schwab CM, Suarez ES, et al. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographics 2002;22(4):911-934.

22 Answer A. Imipramine is a tricyclic antidepressant that may inhibit localization of radioiodinated MIBG. Therefore, this drug should be discontinued before imaging when practical. Other drugs that may similarly inhibit localization of radioiodinated MIBG and that should be withheld if possible prior to imaging include insulin, reserpine, other tricyclic antidepressants, and amphetamine-like drugs. None of the other drugs listed need to be withheld prior to imaging.

Reference: Mettler FA, Guiberteau MJ. Essentials of nuclear medicine, 6th ed. Philadelphia, PA: Elsevier/Saunders, 2012.

23 Answer B. There is a special stage in the staging of neuroblastoma known as IV-S, which is given to patients who are diagnosed at less than a year of age with metastatic disease that is confined to the skin, liver, and bone marrow. Cortical bone involvement is not considered to be part of IV-S. Children diagnosed with IV-S tumors have a good prognosis and a 3-year event-free survival rate of 75% to 90%.

References: Donnelly LF. Pediatric imaging the fundamentals. Philadelphia, PA: Elsevier/Saunders, 2009.

Lonergan GJ, Schwab CM, Suarez ES, et al. Neuroblastoma, ganglioneuroblastoma, and ganglioneuroma: radiologic-pathologic correlation. Radiographic 2002;22(4):911-934.

24 Answer D. The CT image demonstrates a heterogeneous solid mass arising from the left kidney as evidenced by a rim of renal tissue medially (arrows) consistent with a “claw sign.” In a 2-month-old patient, this lesion most likely represents a congenital mesoblastic nephroma (CMN). Congenital mesoblastic nephroma is the most common solid renal tumor in the neonate. It is usually identified within the first 3 months of life, with 90% of cases discovered within the first year of life. Imaging studies demonstrate a large solid intrarenal mass that typically involves the renal sinus. The mass replaces a large portion of renal parenchyma and may contain cystic, hemorrhagic, and necrotic regions. CMN was first described in 1967 as a benign leiomyoma-like tumor. Current research now suggests that a spectrum of disease exists, ranging from the classic benign CMN to a more aggressive cellular CMN variant, which accounts for 42% to 63% of cases.

The peak age of Wilms tumor is at 3 to 4 years of age. It is rare in neonates, with <0.16% of cases manifesting in this age group. Renal cell carcinoma has been reported in patients <6 months of age. However, the tumor is rare in children, accounting for <7% of all primary renal tumors presenting in the first two decades of life. Less than 2% of all cases of renal cell carcinoma occur in pediatric patients, with a peak incidence in the sixth decade of life. Renal medullary carcinoma is a highly aggressive malignant tumor that occurs almost exclusively in adolescent and young adult blacks with sickle cell trait or hemoglobin SC disease. The age range is 10 to 39 years with a mean age of 20 years.

References: Lowe LH, Isuani BH, Heller RM, et al. Pediatric renal masses: Wilms tumor and beyond. Radiographics 2000;20(6):1585-1603.

Sheth MM, Cai G, Goodman TR. AIRP best cases in radiologic-pathologic correlation: congenital mesoblastic nephroma. Radiographics 2012;32(1):99-103.

25 Answer A. Congenital mesoblastic nephroma (CMN) is the most common renal tumor in neonates and in infants under 1 year of age. CMN was first described in 1967 as a benign leiomyoma-like tumor. Current research now suggests that a spectrum of disease exists, ranging from the classic benign CMN to a more aggressive cellular CMN variant, which accounts for 42% to 63% of cases. The imaging appearances of CMN vary depending on tumor composition, because classic variants are predominantly solid, whereas cellular variants are largely cystic. Unfortunately, many diverse disease processes may present as a solid, cystic, or mixed renal mass within the first year of life. The differential diagnosis is broad and includes renal and nonrenal tumors such as Wilms tumor, clear cell sarcoma, rhabdoid tumors, neuroblastoma, and multilocular cystic renal tumor. Although patient history, presentation, and associated findings can suggest a particular diagnosis, in many cases, a definitive diagnosis can be made only on the basis of histopathologic findings.

Reference: Sheth MM, Cai G, Goodman TR. AIRP best cases in radiologic-pathologic correlation: congenital mesoblastic nephroma. Radiographics 2012;32(1):99-103.

26 Answer C. Minimally invasive endoscopic treatment or periureteral injection is considered for the treatment of vesicoureteral reflux (VUR) when the degree of VUR is severe, if there is evidence of renal scarring, if the reflux has not resolved over a reasonable time, or if breakthrough infections occur frequently. After periureteral injection, ultrasound will show an iso- or hyperechoic mounds in the bladder wall in the region of the ureteral orifices without posterior acoustic shadowing. A dextranomer-hyaluronic acid copolymer (Deflux) has been used as an injectable material in pediatric urology for 15 years. Dextranomer-hyaluronic acid copolymer is currently the most commonly used agent and will consequently be most frequently encountered on imaging studies. Deflux mounds are not a treatment for distal ureteral calculi. They should not be mistaken for rhabdomyosarcomas or other bladder masses based on their characteristic location and imaging features. They should also not be mistaken for bladder wall trabeculations which are often seen in neurogenic bladders.

References: Cerwinka WH, Kaye JD, Scherz HC, et al. Radiologic features of implants after endoscopic treatment of vesicoureteral reflux in children. Am J Roentgenol 2010;195(1):234-240.