© 2002 by the American Institute of Ultrasound in Medicine
J Ultrasound Med 21:801-806 • 0278-4297
Diagnosis and Follow-up of Craniopharyngiomas With Transcranial Doppler Sonography
Kuang-Lin Lin, MD,
Huei-Shyong Wang, MD and
Tai-Ngar Lui, MD
Divisions of Pediatric Neurology (K.-L.L., H.-S.W.) and Neurosurgery (T.-N.L.), Chang Gung Children's Hospital at Linkou, Chang Gung University, Taoyuan, Taiwan, Republic of China.
Address correspondence and reprint requests to Huei-Shyong Wang, MD, Division of Pediatric Neurology, Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University, 5 Fu-Shin St, Kweishan 333, Taoyuan, Taiwan, Republic of China.
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Abstract
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Objective. Craniopharyngiomas are the most common parasellar neoplasms in children. Because it is difficult to diagnose subtle visual or endocrinologic changes in young children at an early stage, craniopharyngiomas may grow to a considerable size before diagnosis. Methods. We used transcranial Doppler sonography to diagnose and follow up 5 patients with craniopharyngiomas. There were 3 girls and 2 boys aged from 6 years 4 months to 10 years. Results. The initial manifestations were visual defects (n = 4), headaches (n = 3), and growth restriction (n = 1). One patient had a diagnosis of a craniopharyngioma on the basis of sonography before brain computed tomography. All 5 patients were examined with transcranial color Doppler sonography before surgery and for postoperative follow-up. Sonography showed a cystic component with calcification in 4 patients and a solid component in 1 patient; these findings were compatible with the computed tomographic findings. Displacement of the vessels of the circle of Willis was found. Tumor recurrences were detected early on transcranial sonography in 4 patients at 1 to 8 months' follow-up; these were proved by computed tomography. Conclusions. Transcranial Doppler sonography is a convenient tool for the diagnosis, evaluation, and follow-up of craniopharyngiomas. It can adequately describe vessels around the tumors and show tumor recurrence at an early stage.
Key Words: craniopharyngioma • sonography • transcranial Doppler Abbreviations: CT, computed tomography • MR, magnetic resonance
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Introduction
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Craniopharyngiomas are the most common nonglial tumors observed in infancy and childhood.1 They are considered to arise from embryonic squamous cell rests of an incompletely involuted hypophyseal-pharyngeal duct; such rests can occur anywhere from the infundibulum to the tuber cinereum and even in the pituitary gland itself.2 Because subtle visual or endocrinologic changes are difficult to diagnose at an early stage in young children, a craniopharyngioma may grow to a considerable size before diagnosis. It also behaves as an aggressive tumor and carries an elevated risk of recurrence.3,4 The traditional diagnostic imaging tools for a craniopharyngioma are plain skull radiographs, computed tomography (CT) scans, magnetic resonance (MR) imaging, and angiography.2 In this study, we used transcranial Doppler sonography to disclose the craniopharyngiomas and to detect their recurrence.
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Materials and Methods
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From January 1998 to July 1999, we used transcranial Doppler sonography to diagnose and follow up 5 patients (3 girls and 2 boys, 6 years 4 months to 10 years old) with craniopharyngiomas, which were proved pathologically. Initial manifestations included visual defects (n = 4), headaches (n = 3), and growth restriction (n = 1). One patient was examined because of his visual defect. Four patients were examined after a diagnosis of craniopharyngioma on the basis of CT. All 5 patients were examined postoperatively at intervals of 2 weeks in the first month and 4 weeks in the subsequent 3 months or until clinical symptoms declined. When patients were thought to have tumor recurrence, they underwent brain CT or MR imaging to confirm the sonographic findings.
We used a 2-MHz transducer with a combination of color-coded Doppler, power Doppler, and two-dimensional real-time sonography (128XP; Acuson, a Siemens Company, Mountain View, CA). The color Doppler velocity scale (Nyquist limit) was set at 30 cm/s. When the blood flow exceeded this limit, color wraparound occurred (the aliasing effect). Two acoustic windows were available for transcranial insonation: (1) the transtemporal approach and (2) the supraorbital approach.5 Follow-up periods were 7 to 15 months.
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Results
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The preoperative sonographic findings of craniopharyngioma and the clinical manifestations of the patients are summarized in Table 1 . In patient 1, sonograms from the transcranial supraorbital approach (axial view) showed a well-defined cystic mass with a calcified capsule (Fig. 1A). A good relative position with the pituitary fossa was shown in the sagittal view from the supraorbital approach (Fig. 1B). In patient 2, sonograms from the transcranial temporal and supraorbital approaches showed a mass before the midbrain with abnormal echogenicity mixed with some hyperechoic spots (Fig. 1, C and D). In this study, within the sellar area, 4 patients had an abnormal anechoic mass, 1 had an abnormal echogenic mass, 4 had rim echogenicity, 2 had rim hyperechogenicity, and 2 had spot hyperechogenicity, findings which were proved by CT or MR imaging with the cystic component, solid component, capsule, capsule calcification, and calcified nodules, respectively (Table 2). Four patients were found to have tumor recurrence on sonography at 1 to 8 months postoperatively. The sonographic findings indicated increased tumor size (n = 4), wide separation of the capsule wall (n = 4), and displacement of the vessels of the circle of Willis (n = 4). In patient 4, sonographic follow-up after surgery showed disappearance of the tumor mass and progressive recurrence at 2 and 4 months postoperatively (Fig. 2), which correlated with results of brain CT and MR imaging (Fig. 3).
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Discussion
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The most common apparent symptoms of children with craniopharyngiomas are headaches, vomiting, and visual disturbances.6 Although endocrine disturbances can be found in 80% to 90% of patients when the common symptoms appear, few patients seek medical attention for endocrine-related symptoms.7 Because of its subtle clinical manifestations, a craniopharyngioma is difficult to diagnose early in young children. It may grow to a considerable size before diagnosis. Brain CT or MR imaging might be performed late, only when symptoms are obvious. To detect craniopharyngiomas early, transcranial sonography should be used as an alternative and effective tool to screen the sellar area and circle of Willis, as in our patient 5, whose sellar mass was shown before CT was performed.
The characteristics of CT images of craniopharyngiomas are intrasellar calcifications and enhancement of the solid portion and often the cyst capsule by contrast agents. Magnetic resonance imaging can obtain a good mass-brain interface, especially in the sagittal plane, a view not available by any other method. A fast T2 sagittal image is often useful to further assess the cystic component. Visualization of the major vessels of the pentagon of Willis provides an additional bonus.2 In this study, sonograms of the craniopharyngiomas showed the following characteristics: a sellar echogenic or anechoic tumor mass associated with (1) rim echogenicity, (2) rim hyperechogenicity, or (3) spot echogenicity. These pictures are compatible with a solid component or cystic component tumor mass with (1) capsule formation, (2) capsule calcification, or (3) calcification spots, respectively.
The recurrence rates reported in the literature vary greatly from 0% to almost 100% depending on the efficacy of the surgical treatment and adjuvant therapy as well as on the growth potential of the tumor itself. Whatever the cause, recurrence represents one of the most common complications of craniopharyngioma treatment and poses many management problems.1 Postoperative follow-up is usually achieved by a combination of CT and MR imaging. Follow-up imaging studies should occur at 6 to 9 months, a time that may vary from surgeon to surgeon, or unless clinical symptoms determine otherwise.2 With the use of the supraorbital window introduced by Wang and Kuo,5 transcranial sonography combined with color Doppler imaging can clearly show the sellar area and circle of Willis.8–10 When color-coded Doppler sonography cannot produce good insonation of the circle of Willis, power Doppler sonography can be an improvement.11 In this study, we followed up using brain sonography at short intervals. We detected tumor recurrences in the absence of clinical symptoms as early as 1 month postoperatively; these were proved by brain CT or MR imaging. The direct sonographic evidence included (1) increased size of the anechoic tumor mass, (2) increased size of the heterogeneous echogenic tumor mass, and (3) increased width of the capsule wall, whereas indirect evidence included (1) displacement of the vessels of the circle of Willis and (2) increased width of the circle of Willis.
Use of the multimodal approach of transcranial color Doppler sonography can clearly show the vessels around the craniopharyngioma and can show tumor recurrence at an early postoperative time. In this study, we showed that transcranial sonography can be a convenient and effective tool for diagnosis and follow-up of craniopharyngiomas.
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Footnotes
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Received December 12, 2001, from the Divisions of Pediatric Neurology (K.-L.L., H.-S.W.) and Neurosurgery (T.-N.L.), Chang Gung Children's Hospital at Linkou, Chang Gung University, Taoyuan, Taiwan, Republic of China.
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References
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Abstract
Introduction
