Autosomal recessive (infantile) polycystic kidney disease demonstrated by Tc-99m DMSA renal imaging

The role of 99mTc DMSA renal scintigraphy in Joubert syndrome

Joubert syndrome is a severe autosomal recessive disorder, which is characterized by hypotonia, impaired psychomotor development, retinal dystrophy with abnormal ocular movements and cerebellar vermis agenesis with dilatation of the fourth ventricle. Joubert syndrome type B is a developmental disorder of the nephronophtisis complex with multiple organ involvement. Although this syndrome is rare, since first described by Joubert et al in 1969, there have been several cases about the components and the chromosomal abnormalities related with it. Here we report 2 patients with Joubert syndrome in whom renal involvement was demonstrated by ultrasonography as renal cystic disorders which represented nephronophtisis. For each patient we performed renal cortical scintigraphy with 99mTc-DMSA ( 99mtechnetium-dimercaptosuccinic acid) which showed bilaterally decreased radiopharmaceutical uptake in kidneys due to tubulointerstitial nephropathy. Scintigraphy may have a great value in the diagnosis and evaluation of the presence and severity of renal involvement in Joubert syndrome since it can evaluate kidney parenchyma and functioning renal tissue.

The value of radionuclide studies in children with autosomal recessive polycystic kidney disease

PURPOSE

To describe and analyze the appearances of autosomal recessive polycystic kidney disease (ARPKD) on Tc-99m DMSA and Tc-99m HIDA scintigraphy.

MATERIALS AND METHODS

The authors evaluated scintigraphic findings for 13 boys and 9 girls (age range, 2 months to 22.75 years; mean, 7.5 years) with ARPKD. Fourteen children underwent Tc-99m DMSA and 20 underwent Tc-99m HIDA scintigraphy according to European guidelines. Kidney outline, internal structure, tracer uptake, and differential function were analyzed on Tc-99m DMSA images, whereas relative liver lobe sizes, hepatocyte tracer uptake, time to peak, and excretion into the biliary tree and gut were evaluated on Tc-99m HIDA scans.

RESULTS

On Tc-99m DMSA images, loss of kidney outline and internal structure was seen in 75% of the scans, and patchy tracer uptake with focal defects throughout the kidneys, particularly at the poles, was evident in 93%. In 85% of the cases, the Tc-99m DMSA changes did not correlate with the ultrasonographic findings where the kidneys are uniformly affected. Characteristic findings on Tc-99m HIDA scans were enlarged left liver lobe in 80%, a delay in maximal hepatocyte uptake in 68%, delayed tracer excretion into the biliary tree in 32% (with stasis in the prominent intrahepatic biliary ducts in 50% or pooling into the segmentally dilated biliary ducts in 25%), and delayed excretion into the gut in 40% of patients.

CONCLUSIONS

In a child with clinically enlarged kidneys that appear diffusely hyperechoic on ultrasound, the appearances on Tc-99m DMSA imaging strongly support the diagnosis of ARPKD. The Tc-99m HIDA findings, especially of an enlarged left lobe of the liver with bile stasis or dilatation, further support the diagnosis.

Autosomal recessive polycystic kidney disease: radiologic-pathologic correlation

Autosomal recessive polycystic kidney disease is a heritable but phenotypically variable disorder characterized by varying degrees of nonobstructive renal collecting duct ectasia, hepatic biliary duct ectasia and malformation, and fibrosis of both liver and kidneys. In the kidney, the dilated collecting ducts and interstitial fibrosis, when severe, may significantly impair renal function and result in hypertension and renal failure. Imaging typically shows large but reniform kidneys, diffusely increased renal parenchymal echogenicity at ultrasonography, and a striated nephrogram after contrast material administration. In the liver, periportal fibrosis accompanies the malformed and dilated bile ducts; this may result in portal hypertension. The liver may appear normal or may show intrahepatic biliary dilatation; once portal hypertension develops, splenomegaly and varices are usually evident. The relative degrees of kidney and liver involvement tend to be inverse: Children with severe renal disease usually have milder hepatic disease, and those with severe hepatic disease tend to evidence mild renal impairment. Presently, treatment consists of supportive management and control of hypertension. Replacement therapy for renal failure (dialysis or kidney transplantation) and control of portal hypertension (portal circulatory diversion or liver transplantation) may be necessary.