Symposium on Pediatric Oncology
Neuroradiology and Pediatric Oncology
Derek C. Harwood-Nash, Ch.B., F.R.C.P.(CJ*
The aims of neuroradiology in the diagnosis of an intracranial neoplasm initially are to define its precise geography and to determine its character, and subsequently, to detect any recurrence or spread after treatment. The time-honored techniques of ventriculography, pneumoencephalography, angiography, and myelography have sufficed only partially to these ends. Such techniques have been refined to a considerable degree but only lately applied in any great extent to pediatric neuroradiology.6 Furthermore new contrast agents and totally new mechanical and physical roentgenographic concepts have evolved which are altering our neuroradiological diagnostic approach, not only to intracranial neoplasms but to all cerebrospinal abnormalities.
Ventriculography and Pneumoencephalography The performance of satisfactory and sophisticated pneumoencephalography and ventriculography in infants and children demands suitable fixation devices and tomography. The fixation devices must permit infants and children of any weight to be safely manipulated during these procedures. 3 • 13 It is only with such devices and especially with tomography that the precise definition of the ventricles and cisterns can be obtained. Small pineal atypical teratomas, optic gliomas, and hypothalamic gliomas are best examined by pneumotomography. For example, metastasis of pineal teratomas to the hypothalamus creates subtle alterations in the outline of the third ventricle and cisterns not easily detectable by other diagnostic means (Fig. 1). The geography of infratentorial neoplasms, even those that are vascular, is still best studied by ventriculography or pneumoencephalography with tomography. It is often as important to determine without doubt that a suspected lesion is not present as to diagnose its very presence. It is only by use of tomography and pneumoencephalography that adequate examination may be carried out in many children in whom the presence of neoplasms about the third ventricle is suspected. The use 'Head, Division of Pediatric N euroradiology, Department of Radiology, The Hospital for Sick Children, Toronto; Assistant Professor of Radiology, University of Toronto, Toronto, Ontario, Canada Pediatric Clinics of North America-Vol. 23, No.1, February 1976
29
30
DEREK
C.
HARWOOD-NASH
Figure 1. Pneurnotomography and pineal atypical teratoma. A, A standard roentgenograph during pneumoencephalography demonstrates a large calcified mass in the pineal region in a 10 year old child. B, Coronal pneurnotomography demonstrates elevation of the floor of the third ventricle (closed arrow) and a mass in the hypothalamus (open arrow), representing forward spread by continuity of a pineal atypical teratoma.
NEUROR.>\DIOLOGY AND PEDIATRIC ONCOLOGY
31
of optic canal tomography will further facilitate the geographic differentiation of such lesions as optic chiasm, nerve gliomas, and craniopharyngiomas. 4
Angiography Selective percutaneous catheter cerebral angiography should be the only method of angiography performed3 and has been shown to be quite safe. 7 Brachial and direct puncture cerebral angiography are often relatively difficult, crude, and may be dangerous when performed on infants and children. The use of anesthesia and hyperventilation is strongly advised during angiography. Hyperventilation, which lowers the pC0 2 of26 to 30 mm of mercury, permits better visualization of abnormal cerebral vessels, which are refractory to the vasoconstrictive effect of the lowered pC0 2 • Thus subtle neoplastic vessels and "stains" (Fig. 2) are better detected in both primary intracranial neoplasms and secondary spread within the cerebrospinal fluid system. The author believes that without such a technique, some smallinfiltrating gliomas and metastases would be missed. Magnification (2 x) and subtraction roentgenography is, of course, mandatory in order to best visualize vessels of 100 microns or more in diameter.
Myelography More often than not, children in whom there is suspected metastasis of an intracranial neoplasm to the spinal subarachnoid space are not referred for myelography but rather are treated arbitrarily with radiation therapy. The identification of such spread (Fig. 3), and in particular of local mass effects, is important though management of the child be by laminectomy and decompression with or without possible further radiation. An urgent and aggressive myelographic approach 5 must be practiced in the management of children with even the most subtle clinical suggestion of an intraspinal mass lesion that may be secondary to spread from intracranial origin. A new water soluble contrast medium (Metrizamide)l1 will significantly add to the precision and ease of myelography in infants and children. It mixes freely with cerebrospinal fluid, absorbs less x-rays than oily contrast media, and therefore provides a better definition of the spinal cord and its nerve roots.
Cystography Micropulverized barium, if injected directly into a cerebral cystic neoplasm, will outline a possible mural nodule (Fig. 4) to the benefit of surgical removal and/or radiation therapy.
Cranial Computed Tomography The new, sophisticated, and exciting roentgenographic technique of computed tomography!. 2, 9, 12 provides much of the initial clinical data in adults. Experience with this technique in infants and children is considerably less however.s, 10 The geography of an intracranial neoplasm, other than those deep within cerebral tissue, is still obtained crudely relative to the precision of pneumotomography and magnification angiText continued on page 34
32
DEREK
C.
HARWOOD-NASH
Figure2.2. Angiography, Angiography,intracranial intracranialneoneoFigure plasmsand andhyperventilation. hyperventilation.A, A, AAlarge large epenepenplasms dymomaofofthe thefourth fourthventricle ventricledisplacing displacingthe the dymoma posteriorinferior inferiorcerebral cerebral artery artery upward upward and and posterior markedlystretching stretchingits itsperipheral peripheralbranches branchesas as markedly anextensive extensivebut butwell welldefined defined fine fine neoplastic neoplastic an vascularblush blush(arrow). (arrow ).This Thisoutlines outlines the the full full vascular extent of ofthe the tumor. tumor . Band Band C, C, Vertebral Vertebral extent angiographydemonstrates demonstratesaadelicate delicatehomogehomogeangiography nousblush blush(open (openarrows) arrows)in inthe theregion regionof ofthe the nous righttrigone trigoneininboth boththe thelateral lateral(B) (B)and andanteroposterior anteroposterior(C) (C) projections. projections. The The normal normal glomus glomus is is right seenon onthe theother otherside side(closed (closedarrow). arrow).This Thistoo toowas wasan anependymoma ependymomabut butof ofthe thelateral lateral ventricle. ventricle. seen
---
.. NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
Figure 3. Myelography and subarachnoid tumor spread. A cerebral sarcoma seeding to the lumbar region. Note characteristic multiple irregular nodular masses in the lumbar arachnoid.
33
-
34
-
-
~~------------------------
DEREK
C.
HARWOOD-NASH
Figure 4. Barium cystography and neoplastic cysts. A large cerebral cystic astrocytoma cyst had micropaque instilled at tapping. Note the large mural nodule.
ography. More important, however, is that characteristics of the neoplasm such as vascularity and content, and the presence of calcification in a suspect mass lesion such as craniopharyngioma (Fig. 5) or atypical pineal teratoma (Fig. 6), are demonstrated beautifully by computed tomography. Calcification not visualized on standard roentgenographs, in addition to the size and site of these neoplasms, often is demonstrated by computed tomography. The presence of a cystic component to the intracranial neoplasm (Fig. 7) is probably the most valuable practical benefit of computed tomography other than its simple and safe diagnostic modality. The recurrence of a solid or cystic neoplasm within the cranium, and possible metastasis are quickly, safely, and accurately determined. The natural history of intracranial neoplasms may be charted; in some children an initially negative finding may evolve within months into a large malignant astrocytoma
-
4
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
35
Figure 5. Computed tomography and craniopharyngioma. A, A central dense appearing craniopharyngioma cyst .surrounded by calcification (arrows). B, Contrast enhancement outlines the capsule with traumatic visualization of the contained cyst.
(Fig. 8). Computed tomography has become the most subtle and accurate technique in the initial neuroradiological detection of intracranial neoplasms and in the evaluation of their characteristics. It is still important, however, to utilize pneumotomography and angiography in many such cases in order to provide the clinician with complete details regarding the lesion. Computed tomography is less successful in detecting smalllesions
Figure 6. Pineal atypical teratoma. Densely calcified atypical pineal teratoma is present. The artefact on the left is a shunt tube.
36
DEREK
C.
HARWOOD-NASH
Figure 7. Computed tomography and cystic astrocytomas. A and B, A right cerebellar astrocytoma (open arrows) together with a large cyst (closed arrows). The pathological specimen (B) demonstrates to a striking degree the tumor nodule and cystic component as seen on computed tomography (vertical orientation of pathological specimen). C andD, A large midline cyst in the posterior fossa (C). Contrast enhancement computed tomography (D) clearly demonstrates the neoplastic cyst and the mural tumor nodule. The artefact superiorly is a shunt.
I
in and about the sella and third ventricle and does not characterize vascular structures, but rather provides visualization and detection of possible cerebral sequelae to these latter abnormalities. Contrast enhanced computed tomography is mandatory in all children in whom an intracranial neoplasm is suspected (Fig. 9).
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
37
Figure 8. The natural history of acoustic neuromas. A, Initial contrast enhanced computed tomography demonstrates a large left sided acoustic neuroma (arrow). B, Eight months later after removal of the left acoustic neuroma, contrast enhanced computed tomography demonstrates a huge acoustic neuroma (arrow) on the right side, a site that was normal eight months previously.
Figure 9. Contrast enhanced computed tomography and neoplasms. A, A suspect left cerebral neoplasm demonstrates some edema in the left frontal lobe on standard computed tomography. B, Contrast enhanced computed tomography clearly demonstrates the site and size of a grade II astrocytoma.
38
DEREK
Figure
10.
C.
HARWOOD-NASH
Sequelae of intra-
Figure 10. Sequelae of intrathecal methotrexate. A, A child with pial thecal methotrexate. A ,cell A child withdemonpial spread of a reticulum sarcoma spread of reticulum cell sarcoma demonstrates adense track-like calcifications strates dense both track-like calcifications throughout hemispheres subsethroughout hemispheres subse quent to both intrathecal methotrexate. quent to intrathecal methotrexate. B, Computed tomography demonstrates B,the Computed tomography demonstrates extensive superficial calcification the extensive which extendssuperficial deeply into calcification cerebral tissue which extends deeply into cerebral tissue and even into the head of the caudate and even into the other head computed of the caudate nucleus and on tomognucleus and on into otherthe computed raphy sections thalami. tomography sections into the thalami.
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
39
Failure to employ this technique means that negative standard computed tomography will often be associated with a significant cerebral neoplasm. Finally chemotherapeutic agents administered intrathecally may have a devastating effect on the brain. Intrathecal methotrexate can cause brain tissue necrosis creating track-like calcifications along a gyral pattern (Fig. 10). Computed tomography however will demonstrate that this damage, as inferred by calcification, actually extends far into the brain and even involves the basal ganglia. Rarely, the treatment may be more devastating than the initial disease.
Summary The more recent techniques of ventricular tomography and pneumotomography with adequate infantile fixation; percutaneous selective catheter cerebral angiography with magnification, hyperventilation, and subtraction; safe water soluble myelography compounds; and most important, the advent of computed tomography, have made the neuroradiological study of intracranial and intraspinal neoplasia a precise art. The philosophy that the more one knows about the character and geography of a neural neoplasm in a child, within clinical and technical limits, will lead to better and correct treatment methods and ultimately a more hopeful individual prognosis. REFERENCES J.: Computerized transverse axial scanning (tomography). II. Clinical application. Brit. J. Radiol., 46:1023, 1973. Baker, H., Campbell, J., and Houser, D.: Computer assisted tomography of the head. Mayo Clin. Proc., 49:747, 1974. Fitz, C. R., and Harwood-Nash, D. C.: Special procedure techniques in infants. Radiol. Clin. North Am., 13:181, 1975. Harwood-Nash, D. C.: Axial tomography of the optic canals in children. Radiology, 96:367-374, 1970. Harwood-Nash, D. C.: Myelography in children. Sem. Roentgenol., 7:297-312, 1972. Harwood-Nash, D. C.: Pediatric neuroradiology. Radiol. Clin. North Am., 10:313-331, 1972. Harwood-Nash, D. C., and Fitz, C. R.: Complications of pediatric arteriography. In Gyepes, M. T. (ed.): Angiography in Infants and Children. New York, Grune & Stratton, Inc., 1974, Ch. 10. Harwood-Nash, D. C., Fitz, C. R., and Reilly, B. J.: Cranial computed tomography in infants and children. Canad. Med. Assoc. J., 113: Sept. 20,1975. Hounsfield, G. H.: Computerized transverse axial scanning(tomography).1. Description of system. Brit. J. Radiol., 46:1016, 1973. Houser, O. W., Smith, J. B., Gomez, M. R., et al.: Evaluation of intracranial disorders in children by computerized transaxial tomography: A preliminary report. Neurology, 25 :607, 1975. Metrizamide. A non-ionic water-soluble contrast medium. Acta Radiol., Supplement 335, Stockholm, 1973. New, P. F. J., and Scott, W. R.: Computed Tomography of the Brain and Orbit (EMI Scanning). Baltimore, Williams & Wilkins Co., 1975. Reilly, B. J., and Harwood-Nash, D. C.: Radiological examination of the newborn. Radiol. Clin. North Am., 13:171,1975.
1. Ambrose,
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Department of Radiology The Hospital for Sick Children 555 University Avenue Toronto, Ontario M5G lX8 Canada
Neuroradiology and Pediatric Oncology
Derek C. Harwood-Nash, Ch.B., F.R.C.P.(CJ*
The aims of neuroradiology in the diagnosis of an intracranial neoplasm initially are to define its precise geography and to determine its character, and subsequently, to detect any recurrence or spread after treatment. The time-honored techniques of ventriculography, pneumoencephalography, angiography, and myelography have sufficed only partially to these ends. Such techniques have been refined to a considerable degree but only lately applied in any great extent to pediatric neuroradiology.6 Furthermore new contrast agents and totally new mechanical and physical roentgenographic concepts have evolved which are altering our neuroradiological diagnostic approach, not only to intracranial neoplasms but to all cerebrospinal abnormalities.
Ventriculography and Pneumoencephalography The performance of satisfactory and sophisticated pneumoencephalography and ventriculography in infants and children demands suitable fixation devices and tomography. The fixation devices must permit infants and children of any weight to be safely manipulated during these procedures. 3 • 13 It is only with such devices and especially with tomography that the precise definition of the ventricles and cisterns can be obtained. Small pineal atypical teratomas, optic gliomas, and hypothalamic gliomas are best examined by pneumotomography. For example, metastasis of pineal teratomas to the hypothalamus creates subtle alterations in the outline of the third ventricle and cisterns not easily detectable by other diagnostic means (Fig. 1). The geography of infratentorial neoplasms, even those that are vascular, is still best studied by ventriculography or pneumoencephalography with tomography. It is often as important to determine without doubt that a suspected lesion is not present as to diagnose its very presence. It is only by use of tomography and pneumoencephalography that adequate examination may be carried out in many children in whom the presence of neoplasms about the third ventricle is suspected. The use 'Head, Division of Pediatric N euroradiology, Department of Radiology, The Hospital for Sick Children, Toronto; Assistant Professor of Radiology, University of Toronto, Toronto, Ontario, Canada Pediatric Clinics of North America-Vol. 23, No.1, February 1976
29
30
DEREK
C.
HARWOOD-NASH
Figure 1. Pneurnotomography and pineal atypical teratoma. A, A standard roentgenograph during pneumoencephalography demonstrates a large calcified mass in the pineal region in a 10 year old child. B, Coronal pneurnotomography demonstrates elevation of the floor of the third ventricle (closed arrow) and a mass in the hypothalamus (open arrow), representing forward spread by continuity of a pineal atypical teratoma.
NEUROR.>\DIOLOGY AND PEDIATRIC ONCOLOGY
31
of optic canal tomography will further facilitate the geographic differentiation of such lesions as optic chiasm, nerve gliomas, and craniopharyngiomas. 4
Angiography Selective percutaneous catheter cerebral angiography should be the only method of angiography performed3 and has been shown to be quite safe. 7 Brachial and direct puncture cerebral angiography are often relatively difficult, crude, and may be dangerous when performed on infants and children. The use of anesthesia and hyperventilation is strongly advised during angiography. Hyperventilation, which lowers the pC0 2 of26 to 30 mm of mercury, permits better visualization of abnormal cerebral vessels, which are refractory to the vasoconstrictive effect of the lowered pC0 2 • Thus subtle neoplastic vessels and "stains" (Fig. 2) are better detected in both primary intracranial neoplasms and secondary spread within the cerebrospinal fluid system. The author believes that without such a technique, some smallinfiltrating gliomas and metastases would be missed. Magnification (2 x) and subtraction roentgenography is, of course, mandatory in order to best visualize vessels of 100 microns or more in diameter.
Myelography More often than not, children in whom there is suspected metastasis of an intracranial neoplasm to the spinal subarachnoid space are not referred for myelography but rather are treated arbitrarily with radiation therapy. The identification of such spread (Fig. 3), and in particular of local mass effects, is important though management of the child be by laminectomy and decompression with or without possible further radiation. An urgent and aggressive myelographic approach 5 must be practiced in the management of children with even the most subtle clinical suggestion of an intraspinal mass lesion that may be secondary to spread from intracranial origin. A new water soluble contrast medium (Metrizamide)l1 will significantly add to the precision and ease of myelography in infants and children. It mixes freely with cerebrospinal fluid, absorbs less x-rays than oily contrast media, and therefore provides a better definition of the spinal cord and its nerve roots.
Cystography Micropulverized barium, if injected directly into a cerebral cystic neoplasm, will outline a possible mural nodule (Fig. 4) to the benefit of surgical removal and/or radiation therapy.
Cranial Computed Tomography The new, sophisticated, and exciting roentgenographic technique of computed tomography!. 2, 9, 12 provides much of the initial clinical data in adults. Experience with this technique in infants and children is considerably less however.s, 10 The geography of an intracranial neoplasm, other than those deep within cerebral tissue, is still obtained crudely relative to the precision of pneumotomography and magnification angiText continued on page 34
32
DEREK
C.
HARWOOD-NASH
Figure2.2. Angiography, Angiography,intracranial intracranialneoneoFigure plasmsand andhyperventilation. hyperventilation.A, A, AAlarge large epenepenplasms dymomaofofthe thefourth fourthventricle ventricledisplacing displacingthe the dymoma posteriorinferior inferiorcerebral cerebral artery artery upward upward and and posterior markedlystretching stretchingits itsperipheral peripheralbranches branchesas as markedly anextensive extensivebut butwell welldefined defined fine fine neoplastic neoplastic an vascularblush blush(arrow). (arrow ).This Thisoutlines outlines the the full full vascular extent of ofthe the tumor. tumor . Band Band C, C, Vertebral Vertebral extent angiographydemonstrates demonstratesaadelicate delicatehomogehomogeangiography nousblush blush(open (openarrows) arrows)in inthe theregion regionof ofthe the nous righttrigone trigoneininboth boththe thelateral lateral(B) (B)and andanteroposterior anteroposterior(C) (C) projections. projections. The The normal normal glomus glomus is is right seenon onthe theother otherside side(closed (closedarrow). arrow).This Thistoo toowas wasan anependymoma ependymomabut butof ofthe thelateral lateral ventricle. ventricle. seen
---
.. NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
Figure 3. Myelography and subarachnoid tumor spread. A cerebral sarcoma seeding to the lumbar region. Note characteristic multiple irregular nodular masses in the lumbar arachnoid.
33
-
34
-
-
~~------------------------
DEREK
C.
HARWOOD-NASH
Figure 4. Barium cystography and neoplastic cysts. A large cerebral cystic astrocytoma cyst had micropaque instilled at tapping. Note the large mural nodule.
ography. More important, however, is that characteristics of the neoplasm such as vascularity and content, and the presence of calcification in a suspect mass lesion such as craniopharyngioma (Fig. 5) or atypical pineal teratoma (Fig. 6), are demonstrated beautifully by computed tomography. Calcification not visualized on standard roentgenographs, in addition to the size and site of these neoplasms, often is demonstrated by computed tomography. The presence of a cystic component to the intracranial neoplasm (Fig. 7) is probably the most valuable practical benefit of computed tomography other than its simple and safe diagnostic modality. The recurrence of a solid or cystic neoplasm within the cranium, and possible metastasis are quickly, safely, and accurately determined. The natural history of intracranial neoplasms may be charted; in some children an initially negative finding may evolve within months into a large malignant astrocytoma
-
4
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
35
Figure 5. Computed tomography and craniopharyngioma. A, A central dense appearing craniopharyngioma cyst .surrounded by calcification (arrows). B, Contrast enhancement outlines the capsule with traumatic visualization of the contained cyst.
(Fig. 8). Computed tomography has become the most subtle and accurate technique in the initial neuroradiological detection of intracranial neoplasms and in the evaluation of their characteristics. It is still important, however, to utilize pneumotomography and angiography in many such cases in order to provide the clinician with complete details regarding the lesion. Computed tomography is less successful in detecting smalllesions
Figure 6. Pineal atypical teratoma. Densely calcified atypical pineal teratoma is present. The artefact on the left is a shunt tube.
36
DEREK
C.
HARWOOD-NASH
Figure 7. Computed tomography and cystic astrocytomas. A and B, A right cerebellar astrocytoma (open arrows) together with a large cyst (closed arrows). The pathological specimen (B) demonstrates to a striking degree the tumor nodule and cystic component as seen on computed tomography (vertical orientation of pathological specimen). C andD, A large midline cyst in the posterior fossa (C). Contrast enhancement computed tomography (D) clearly demonstrates the neoplastic cyst and the mural tumor nodule. The artefact superiorly is a shunt.
I
in and about the sella and third ventricle and does not characterize vascular structures, but rather provides visualization and detection of possible cerebral sequelae to these latter abnormalities. Contrast enhanced computed tomography is mandatory in all children in whom an intracranial neoplasm is suspected (Fig. 9).
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
37
Figure 8. The natural history of acoustic neuromas. A, Initial contrast enhanced computed tomography demonstrates a large left sided acoustic neuroma (arrow). B, Eight months later after removal of the left acoustic neuroma, contrast enhanced computed tomography demonstrates a huge acoustic neuroma (arrow) on the right side, a site that was normal eight months previously.
Figure 9. Contrast enhanced computed tomography and neoplasms. A, A suspect left cerebral neoplasm demonstrates some edema in the left frontal lobe on standard computed tomography. B, Contrast enhanced computed tomography clearly demonstrates the site and size of a grade II astrocytoma.
38
DEREK
Figure
10.
C.
HARWOOD-NASH
Sequelae of intra-
Figure 10. Sequelae of intrathecal methotrexate. A, A child with pial thecal methotrexate. A ,cell A child withdemonpial spread of a reticulum sarcoma spread of reticulum cell sarcoma demonstrates adense track-like calcifications strates dense both track-like calcifications throughout hemispheres subsethroughout hemispheres subse quent to both intrathecal methotrexate. quent to intrathecal methotrexate. B, Computed tomography demonstrates B,the Computed tomography demonstrates extensive superficial calcification the extensive which extendssuperficial deeply into calcification cerebral tissue which extends deeply into cerebral tissue and even into the head of the caudate and even into the other head computed of the caudate nucleus and on tomognucleus and on into otherthe computed raphy sections thalami. tomography sections into the thalami.
NEURORADIOLOGY AND PEDIATRIC ONCOLOGY
39
Failure to employ this technique means that negative standard computed tomography will often be associated with a significant cerebral neoplasm. Finally chemotherapeutic agents administered intrathecally may have a devastating effect on the brain. Intrathecal methotrexate can cause brain tissue necrosis creating track-like calcifications along a gyral pattern (Fig. 10). Computed tomography however will demonstrate that this damage, as inferred by calcification, actually extends far into the brain and even involves the basal ganglia. Rarely, the treatment may be more devastating than the initial disease.
Summary The more recent techniques of ventricular tomography and pneumotomography with adequate infantile fixation; percutaneous selective catheter cerebral angiography with magnification, hyperventilation, and subtraction; safe water soluble myelography compounds; and most important, the advent of computed tomography, have made the neuroradiological study of intracranial and intraspinal neoplasia a precise art. The philosophy that the more one knows about the character and geography of a neural neoplasm in a child, within clinical and technical limits, will lead to better and correct treatment methods and ultimately a more hopeful individual prognosis. REFERENCES J.: Computerized transverse axial scanning (tomography). II. Clinical application. Brit. J. Radiol., 46:1023, 1973. Baker, H., Campbell, J., and Houser, D.: Computer assisted tomography of the head. Mayo Clin. Proc., 49:747, 1974. Fitz, C. R., and Harwood-Nash, D. C.: Special procedure techniques in infants. Radiol. Clin. North Am., 13:181, 1975. Harwood-Nash, D. C.: Axial tomography of the optic canals in children. Radiology, 96:367-374, 1970. Harwood-Nash, D. C.: Myelography in children. Sem. Roentgenol., 7:297-312, 1972. Harwood-Nash, D. C.: Pediatric neuroradiology. Radiol. Clin. North Am., 10:313-331, 1972. Harwood-Nash, D. C., and Fitz, C. R.: Complications of pediatric arteriography. In Gyepes, M. T. (ed.): Angiography in Infants and Children. New York, Grune & Stratton, Inc., 1974, Ch. 10. Harwood-Nash, D. C., Fitz, C. R., and Reilly, B. J.: Cranial computed tomography in infants and children. Canad. Med. Assoc. J., 113: Sept. 20,1975. Hounsfield, G. H.: Computerized transverse axial scanning(tomography).1. Description of system. Brit. J. Radiol., 46:1016, 1973. Houser, O. W., Smith, J. B., Gomez, M. R., et al.: Evaluation of intracranial disorders in children by computerized transaxial tomography: A preliminary report. Neurology, 25 :607, 1975. Metrizamide. A non-ionic water-soluble contrast medium. Acta Radiol., Supplement 335, Stockholm, 1973. New, P. F. J., and Scott, W. R.: Computed Tomography of the Brain and Orbit (EMI Scanning). Baltimore, Williams & Wilkins Co., 1975. Reilly, B. J., and Harwood-Nash, D. C.: Radiological examination of the newborn. Radiol. Clin. North Am., 13:171,1975.
1. Ambrose,
2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.
Department of Radiology The Hospital for Sick Children 555 University Avenue Toronto, Ontario M5G lX8 Canada
