Eur. J. Nucl. Med. 1, 173-175 (1976) European Nuclear Journal of Medicine © by Springer-Verlag 1976 Experiences with the Use of the 13 l l-Hippuran Test as an Indicator in Functional Patency of Ventriculocardiac Shunts in Hydrocephalic Children Matti Sillanp/ifi, Marita Uro, and Antti Ojala Departments of Paediatrics and Radiotherapy, University of Turku, SF-20520 Turku 52, Finland Abstract. In this paper a method is presented that provides information on the function of ventriculo- cardiac shunts in hydrocephalic children. There is good correlation between clinically and operatively demonstrated obstruction of the shunts as well as with clinically found free C.S.F. passage through the shunt. However, the greatest benefit is provided with the aid of the present method in cases with equivocal obstruction of the shunt where in our experience some operations of the shunt could be postponed or completely avoided in some cases. Because of its sim- plicity, safety, rapidity, and easy repeatability the method is recommended for routine ambulatory and hospital use. Introduction We previously (Sillanpfifi et al., 1970) gave a prelimi- nary report on our experiences of t31I-Hippuran in testing the patency of ventriculocardiac shunts in chil- dren with hydrocephalus. The conclusion drawn was that the Hippuran test (HT) is a simple and easily performable method with the special advantage of providing valuable information in cases with clinically suspected obstruction of the shunt. In order to clarify whether our primary impression could be confirmed we have examined 39 consecutive hospitalized children with ventriculocardiac shunts with suspected obstruction (including the previously reported 15 cases). Material and Methods The patient series consisted of 39 children (19 girls and 20 boys) with expansive hydrocephalus admitted to the Department of Pae- diatrics, Turku University Central Hospital. Thirty-seven patients had Spitz-Holter shunts and Rickham reservoirs while two had shunts of the Pudenz-Heyer valve. Hydrocephalus had been diag- nosed before the age of 1 month in 23 (61%), during the 2nd-6th month in 5 (13%), and later in 11 (26%) of the cases. The cause of hydrocephalus was congenital in 20 (50%), posttraumatic in 3 (8%), postinfectious in 5 (13%), and secondary to brain tumor in 11 (29%). The cause of expansion was ventricular blockage of the C.S.F. passage in 23 (59%), disturbance of resorption in 15 (38%), and overproduction in 1 (3%) of the cases. The method of the HT was the same as reported previously (Sillanpfi~iet al., 1970). 13~I-Hippuran (10 gCi) was injected into the Rickham reservoir or into the outer chamber of the Pudenz- Heyer valve and the disappearance of radioactivity from the valve system and the appearance and increase of radioactivity in the urinary bladder were monitored simultaneously using separate col- limators. The HT was performed altogether 77 times on 39 patients. On clinical examination which included evaluation of any signs of increased intracranial pressure, plain skull and chest X-ray and echoencephalography, unequivocal obstruction was found 10 times, equivocal obstruction 33 times, and on 32 occasions there were no signs of disturbance in C.S.F. circulation. In two further cases the test failed because of complete obstruction of the brain catheter, and these were omitted from the present study. An unobstructed passage was interpreted to exist when the radioactivity curve of the shunt started to decline and that of the urinary bladder rise, respectively, during the first 5 min. The curves usually crossed 5-15 min after the injection of the isotope (Fig. 1). An equivocal obstruction showed a slow and partial de- cline and rise, respectively, of the curves. A complete obstruction exhibited no change in the level of the curves (Fig. 2). The effect of "pumping" the valve on the transfer of radioactivity was also investigated (Figs. 1 and 2). The results were statistically analyzed and the following limits of significance were employed: 0.01 <P<0.05 slightlysignificant 0.00l <P<0.0I significant P<0.001 highly significant. Results Table 1 shows the results obtained in the HT compar- ed to the findings on clinical examination and oper- ation. Six cases with clinically unequivocal and four more cases with clinically equivocal obstruction were found to be obstructed with the HT and verified at operation. One further case with an equivocal block of C.S.F. passage on clinical examination was proved to be temporarily obstructed, but later functioning normally. In another case the HT failed to demon-