Radioisotope therapy of cystic craniopharyngeomas

Inr. J. Radrution Oncology EIO/. Phys., Vol. 8, pp. 1581-l Printed in the U S.A. All rights reserved.

585

036~3016/82/09158145603.00/0 Copyright 0 1982 Pergsmon Press Ltd

0 Brief Communication RADIOISOTOPE

THERAPY

OF CYSTIC CRANIOPHARYNGEOMAS

LUDWIG

STRAUSS, M.D., VOLKER STURM, M.D.,* PETER GEORGI, M.D., WOLFGANG SCHLEGEL, PH.D., HERMANN OSTERTAG, PH.D., JOHN H. CLORIUS, M.D., AND GERHARD VAN KAICK, M.D.

German Cancer Research Center and the University of Heidelberg.* Heidelberg. Germany Eighteen patients suffering from cystic craniopharyngeoma were treated with intracavitary irradiation. The beta-emitting radioisotope Wy (2.25 MeV) was instilled into the cyst following stereotactic puncture of the space-occupying lesion. The surgical approach was planned using angiograms and reconstructed transmission computer tomography (TCT) coronal and saggital sections. Therapy was devised to deliver 20,000 rad to the cyst’s wall. Eleven patients received follow-up TCT examinations after four months. Eight of 11 patients had a significant volume decrease in the craniopharyngeoma cyst. In two patients, the cystic volume remained unchanged; one had progression of disease. It is concluded that the intracavitary treatment of cystic craniopharyngeoma will result in a reduction of the size of the space-occupying lesion.

obtained

INTRODUCTION

Craniopharyngeomas

are the most common

tumors

Six to 9% of all intracranial

in childhood.3

in childhood localized grow

are craniopharyngeomas.4

The tumors

slowly

and infiltrate alterations

the hypothalamic

and calcification

can be classified

into one of three groups:’

I. Solid

(10%);

multiple large

2. Small

cyst’s (30%); solitary

cyst

and

tumors

In these

solid tumor

Backlund of

cystic

Stereotactic

puncture

of

the

single

of an isotope.

it

is not

A high radiation initial

treatment

by

of cystic

in the selection

patients

isotope

was Y-90 silicate.

with

Supposing

AND

of the cyst

were used to determine

I8 consecutive therapy

with

patients referred radioisotopes.

for The

I. The volume determined

was 4, the oldest was 59 years old. All

was calculated the precision

from CT images. and accuracy

in a pilot study. Organ volumes

(liver

volumes

to:

Ludwig

initial

Strauss,

Cancer

examination

M.D.,

was

Institute

Research Center, I, West Germany.

We had

of this method and spleen) were

determined in vitro. The avera,ge error of the determination was 10% for volumes smaller than 500 ml. Cyst

were examined

section the cystic part of the tumor

IO set was used. The

Nuclear Medicine. German IO 1949. D-6900 Heidelberg

cyst volume.

MATERIALS

with a cystic craniopharyngeoma

requests

distance

a point source

the volume

time

Reprint

It

of 2.25

is as low as I %) of that of the

For dose calculations

by transmission computer tomography (TCT). A fast fan-beam scanner with a scanning and reconstruction of

an energy

is 2.5 days. The therapeutic

at 7 mm distance

Two procedures

patients

was

of the optimal

must be known.

METHODS

youngest

after place-

Vessel displacement

used for therapy

beta-emitting

source itself.

craniopharyn-

images

angiographic

into the cyst.

The half-life

the energy

at

and sagittal

images obtained

extends only a few millimeters.

dose is deliv-

considerable

cuts were calculated

taken

MeV.

the

geomas with “‘Y.

We report on craniopharyngeoma

demonstrated

and sagittal

ring.

is a pure

results obtained

and 3 mm increment.

onto the corresponding

into consideration

i.v.

in 250 ml, we

ment of the stereotactic

The radioisotope

intracavitary

is followed

generally Coronal

in 8 mm

Following

in space was I x I x 3 mm.

films and onto radiographic

one

approach the

feed.

from the cross sections. The coronal

or

with

tumors

were superimposed

cystic

craniopharyngeomas.’

cyst

ered to the cyst wall. We report following

having

enhancement

4 mm thickness, resolution

enhancement.

tissue.

therapy

this center

without

patients

introduced

radioisotope installation

Solid

structures.

medium

8 mm table

of 75 g megluminamidotrizoat

The theoretical

as belonging

tumors

contrast

and with

chose slices with

are

benign,

3. Craniopharyngeomas

(60%)).

possible to identify Leksell

solid

injection

are frequent.‘.h

The craniopharyngeomas

without

thick-slices,

brain tumors

in the sella area. They are histologically

Regressive

lesions

benign

of

Accepted

PO Box

1581

were

calculated

for publication

as follows.

2 1 April

I982

In each

cross

was outlined

on a

582

Radiation

Oncology 0 Biology 0 Physics

September

1982, Volume 8, Number

9

+ + +

+

40.0..

+

30.0..

+ + +

20.0..

+ +

10.0..

+ + 10.0

02?0

20:0 VOLUME

Fig. I. Comparison of the radioisotope dilution Volumes in excess of 60 ml were excluded.

.

PERCENl 110. 100.

30:0 NUC.

method

.

______--------

_

.

_-~-

-

__-

68

0

in 12 examinations.

-

_-

__---

--L_______ __=n_r_---.--------

/

50:0

with the TCT volume determination

_

/

40:0

CMLI

--__

-I_ --__ --__

90.0

--*

80.0 70.0 60.0 50.0 40.0 30.0 20.0 ___.___---.----

10.0 L-w-_

O-8

----__

-------_

MONTH

0

Fig. 2. Follow-up TCT volume determinations in 11 patients. The minimum follow-up was four months. Seven patients were excluded since TCT examination beyond four months was not available. The volumes are expressed as percent of initial cyst size.

Therapy

of craniopharyngeomas

0 L. STRAUSS et al.

1583

acquired postoperatively at 140 keV (99mTc), and after one and two days in the compton spectrum of 9oY. In some patients the urine excreted during the first week was measured to determine presence of 9oY. CT examinations were made during the first days after surgery, and prior to discharge from the clinic. RESULTS Eighteen patients were included in this study. There was a high correlation between the volumes calculated by TCT and the radioisotope dilution method (Fig. 1). In 7 patients we lacked long-term CT follow-up. One of the seven died of pulmonary embolism 6 months after surgery. Six patients were lost from view when they failed to appear for follow-up examinations. Eleven patients were followed for a minimum of 4 months after surgery. In 8 of the I I patients radioisotope installation resulted in significant reduction of cyst volume (Fig. 2). In 6 patients cyst volume was reduced by at least 30% four months after surgery. In two patients cyst volume remained stationary, and in one there was a small increase in volume during the five months after surgery. The urine measurements show no significant excretion of “‘Y.

Fig. 3. TCT examination of monocystic craniopharyngeoma. ml.

a 44

year-old

patient

with

a

The calculated volume was 53

visual display by the observer. In the enclosed area the number of pixels was determined. The partial volume was obtained by multiplying the number of pixels with the volume of a voxel. Addition of the partial volumes was used to calculate cyst volume. 2 lntraoperatively we used a radioisotope dilution method to assess cyst volume.5 Following stereotactic cyst puncture 2 ml fluid were removed. Five to IO mCi Tc-99m HSA (human serum albumine) in 2 ml isotonic NaCI-solution were instilled into the cyst, and mixed. Another 2 ml fluid was drawn from the cyst and the radioactivity was measured. Since the initial volume and the radioactivity of the Tc-99m HSA was known, the dilution volume was easily calculated by dividing the activity before and after injection and multiplying the result with the initial 2 ml volume. The radiation dose delivered after installation of 9oY is dependent on the cyst volume. A homogenous radioisotope distribution is assumed to exist in the spherical volume. Based on this premise, and using the formula A = (0.109 V)/ F; F = 0.47 V > 50 ml), we obtain a 20,000 rad dose on the cyst wall. Gamma-camera images were

Fig. 4. The TCT image of the same patient demonstrated Figure 2, three weeks after radioisotope therapy. A volume 50.5 ml was calculated.

in of

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Radiation

Oncology

0 Biology

0 Physics

September

1982, Volume

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Number 9

surgical treatment tumor infiltration of hypothalamic structures is possible.‘.h Conventional radiotherapy can also reduce tumor volume.’ The combination of surgery and radiotherapy has led to satisfactory results.’ Complications can arise when alterations of hypothalamic structures occur.’ Isotope leakage can occur after “Y installation. Gamma-camera images should therefore be made after surgery, to document entrapment of the isotope within the cyst. A development of new cysts can occur. which require repeat radioisotope therapy. A complicating possibility of the “Y silicate instillation is the partial irradiation of the opticus nerve. The therapeutic range could be reduced if the lower energy isotope Rhenium- I86 is substituted for 9oY. In one patient a severe disorder of electrolyte balance occurred after therapy. It can not be ruled out that this disturbance resulted from hypothalamic irradiation. One patient with an intrasellar cyst of 20 ml had decreased visual power nine months after therapy. The optic nerve was in close proximity to the cyst’s wall, so that the decrease in visual acquity may have resulted from partial irradiation of the nerve. To increase accuracy, we have begun to obtain the

Fig. 5. Enhanced TCT slice of the same patient (Fig. 2), six months after therapy. The 10.2 volume reveals a significant decrease

of the space-occupying

lesion.

A sequence of examinations demonstrates the course of disease in a 44 year-old female patient with a monocystic craniopharyngeoma. Following pneumencephalography, air was seen in the left frontal ventricle (Fig. 3). The large cyst has a volume of 53 ml. For radioisotope therapy I2 mCi ‘“Y were instilled into the cyst via a right parietal approach. Gamma camera images were obtained immediately after surgery, and in the days after cyst puncture, using the compton spectrum to demonstrate containment of the tracer in the cyst. Three weeks after surgery, a second CT scan demonstrated a cyst volume of 50.5 ml (Fig. 4). Six months after surgical intervention the cyst’s volume was found to be 10.2 ml (Fig. 5). The fourth CT examination was obtained 1l/z years after radioisotope therapy. The volume of the cyst had reached 2.4 ml (Fig. 6). DISCUSSION The results demonstrate that radioisotope therapy will effectively reduce the volume of cystic craniopharyngeomas. The risk of stereotactic puncture is less than that of conventional neurosurgical treatment. Also, following

Fig. 6. Follow-up examination of the patient demonstrated in Fig. 2 I’/> years after radioisotope therapy. The cyst’s volume has decreased to 2.4 ml.

Therapy of craniopharyngeomas 0 L. STRAUSSet al.

required TCT examinations and the angiograms with fixed stereotactic ring. Bergstroem et al. reported that image quality is increased when stereotactic fixation is used.’ In conclusion we feel that small cyst puncture is

1585

possible with the described procedure. The intracavitary installation of a beta-emitting radioisotope promises significant improvement in the treatment of cystic craniopharyngeoma.

REFERENCES I. Bergstroem,

tomogra-

2. Bingas, Neural.

Fortschr.

M., Greitz, T.: Stereotactic computed phy. Am. J. Roentgenoi. 127: 167-I 70, 1976. B., Walter, M.: Das Kraniopharyngoem. Psych&. 36: I 17-I 95, 1968.

3. Claussen, C., Lohkamp, F., Rebien, W., Kuttig, H.: Therapieplanung und Verlaufskontrolle beim Kraniopharyngeom. Strahlen-therapie 153: 744-753, 1977. 4. Fitz, C.R., Wortzmann, G., Harwood-Nash. D.C., Holgate, R.C., Barry, J.F., Bolt, D.W.: Computed tomography in craniopharyngeomas. Radiology 127: 687-691, 1978. 5. Georgi, P., Strauss, L., Sturm, V., Ostertag, H., Sinn, H., Rommel, T.: Prae- und intraoperative Volumenbestimmung

6. 7.

8.

9.

bei Craniopharyngiomcysten. Nucl. Med. 19: 187-l 90, 1980. Ghatak, N.R., Hirano, A., Zimmermann, H.M.: Ultrastructure of a craniopharyngeoma. Cancer 27: I46551 475, I97 I. Kramer, S., Southard, M., Mansfield, C.M.: Radiotherapy in the management of craniopharyngiomas. Am. J. Roentgenol. 103: 44-52, 1968. Kuttig, H.: Strahlentherapie der Tumoren des Zentralnervensystems im Kindesalter. Strahlentherupie 147: 333-341, 1974. Leksell, L., Backlund, E.O., Johansson, L.: Treatment of Acta C’hir. Stand. 133: 345-350. craniopharyngiomas. 1967.