Computed tomography in the evaluation of patients with persistent hyperplastic primary vitreous (PHPV)

Bilateral persistent fetal vasculature due to a mutation in the Norrie disease protein gene

We report a case of a 7-week-old boy with bilateral leukocoria and asymmetric microphthalmia who was found to have Norrie disease. Symmetrically hyperdense globes with no evidence of calcification were seen on CT scan. The MRI showed bilateral retinal hemorrhages resulting in conical vitreous chambers-narrow at the optic disc and widened toward the lens-characteristic of persistent fetal vasculature. Genetic evaluation revealed a previously undescribed mutation in the Norrie disease protein gene.

Case 206: persistent hypertrophic primary vitreous

History This patient was a 20-month-old full-term girl who had not received any routine pediatric care. During a physical examination, left-sided leukocoria was detected. Subsequently, a left-sided cataract was diagnosed. The patient was sent for magnetic resonance (MR) imaging of the brain and orbits.

Bilateral persistent fetal vasculature: a study of 11 cases

PURPOSE

To describe the clinical and radiologic features of patients with bilateral persistent fetal vasculature (PFV).

METHODS

All patients diagnosed with symmetric, bilateral PFV over a 3.5-year period were included in this representative, observational case series. Only patients with more or less symmetrical disease in both eyes were included. Examination under anesthesia was performed in all but 1 case. B-scan ultrasonography of the eye was performed in all cases. A computed tomographic or magnetic resonance imaging scan was done if the ocular ultrasonography was inconclusive. A systemic workup was performed to rule out associated systemic anomalies.

RESULTS

The study group included 11 patients. Of the 22 eyes studied, 20 (91%) showed features of both the anterior and the posterior forms of PFV. Two children tested positive for IgM rubella antibodies. Ten eyes (45.5%) had a horizontal corneal diameter of less than 10 mm. Fifteen eyes (68.2%) had cataract at presentation. Intraocular pressure was >21 mm Hg in 17 eyes (77.3%).

CONCLUSIONS

Microcornea and cataract were common findings. Bilateral PFV cases were more commonly associated with combined anterior and posterior PFV. Bilateral PFV, although infrequent, should be considered in the differential diagnosis of bilateral leukocoria.

From the archives of the AFIP: Pediatric orbit tumors and tumorlike lesions: neuroepithelial lesions of the ocular globe and optic nerve

Tumors and tumorlike lesions of the globe and optic nerve in children represent a different histologic spectrum than in adults; the imaging appearances of these lesions reflect their pathologic features. Retinoblastoma is a tumor of infancy and the most common intraocular tumor in children. There are heritable and nonheritable forms. The most common clinical finding is leukocoria. The differential diagnoses of this sign include several nonneoplastic lesions: Persistent hyperplastic primary vitreous is a congenital persistence of an embryonic structure causing a retrolental mass. The primitive vasculature may produce a septum in the posterior chamber. Coats disease is a vascular malformation of the retina that produces a lipoproteinaceous subretinal exudate. The vascular malformation enhances with intravenous contrast material, and the fat-containing subretinal exudate does not. Larval endophthalmitis is a granulomatous reaction to the dead or dying larvae of Toxocara canis or T. cati. The most important feature that allows differentiation of retinoblastoma from these so-called pseudoretinoblastomas is the presence of calcification in the former. Medulloepithelioma has two histologic forms; the teratoid type may contain calcifications, but it usually arises anteriorly from the ciliary body rather than posteriorly from the retina. Optic nerve glioma is the most common tumor of the optic nerve in children and is frequently associated with neurofibromatosis type 1. These gliomas are usually pilocytic astrocytomas and cause fusiform enlargement of the nerve.

Anatomy and pathology of the eye: role of MR imaging and CT

Since the development of CT and MR imaging, significant progress has been made in ophthalmic imaging. As the technology advanced and MR imaging units improved their ability in term of spatial resolution, the role of MR imaging in ophthalmic imaging has increased accordingly. This article considers the role of MR and CT imaging in the diagnosis of selected pathologies of the eye.

Orbital and ocular imaging using 3- and 1.5-T MR imaging systems

The goal of this article is to familiarize general radiologists and clinicians (particularly ophthalmologists, neuro-ophthalmologists, neurologists, and neurosurgeons) with the recent introduction of clinical MR imaging scanners operating at a magnetic field strength of 3-T and to compare them with the more common standard scanners operating at 1.5-T. In this study, MR imaging at 3-T was found to offer superior depiction of orbital and intracranial anatomy and pathologic findings. Spin echo, high spatial resolution, T2-weighted, thin-section MR imaging sequences are especially useful and sensitive at 3-T for the evaluation of orbital, ocular, and intracranial anatomy and pathologic findings. The authors din that time-of-flight (TOF) MR angiography at 3-T surpasses the best MR angiography at 1.5-T and that two-dimensional TOF venography and three-dimensional contrast MR venography at 3-T offer superior visualization of intracranial and facial veins as compared with MR venography at 1.5-T. We believe that with further quality image production and efficient coil design, 3-T MR imaging should hold the promise of playing an important role in the diagnostic imaging evaluation of ocular, orbital, and optic pathway pathologic findings.

Retinoblastoma and Simulating Lesions: Role of Imaging

Although the diagnosis of retinoblastoma (Rb) is made primarily by means of clinical examination, CT and MR imaging are helpful to confirm the diagnosis, determine the extent of the intraocular tumor, and exclude extraocular or intracranial involvement. They are also valuable in differentiating Rb from lesions that simulate Rb.

Anatomy and Pathology of the Eye: Role of MR Imaging and CT

Since the development of CT and MR imaging, significant progress in ophthalmic imaging has been made. As the technology advanced and MR imaging units improved their ability in terms of spatial resolution, the role of MR imaging in ophthalmic imaging has increased accordingly. This article considers the role of MR and CT imaging in the diagnosis of selected pathologies of the eye.

Medical imaging in pediatric ophthalmology

The use of CT and MR imaging has improved the understanding of many congenital and acquired conditions in pediatric ophthalmology, resulting in more appropriate therapeutic intervention and giving insight into the pathogenesis of these conditions.

Ocular complications of persistent hyperplastic primary vitreous in three dogs

Persistent hyperplastic primary vitreous (PHPV) syndrome associated with either severe ocular complications or multiple ocular lesions was diagnosed in three young dogs, a Samoyed, a Spanish Pachon, and a mixed breed dog. Due to opacification of the anterior ocular structures, B-mode and color-flow Doppler ultrasonography were performed to aid diagnosis. The Samoyed presented with unilateral hyphema; the Spanish Pachon presented with unilateral secondary glaucoma associated with uveitis and hyphema OD and leucocoria OU; and the mixed breed presented with bilateral leucocoria. B-mode ultrasonography of the Samoyed revealed a subcapsular cataract and a hyperechoic tubular structure attached from the optic disk to the posterior lens capsule. In the Spanish Pachon B-mode ultrasonography of the right eye indicated microphakia, cataract formation, and a retrolental mass with a thin hyperechoic strand stretching from the optic disk to the posterior lens; and for the right eye cataract formation, PHPV, retinal detachment, and vitreous hemorrhage. In the mixed breed dog, B-mode ultrasonography of both eyes indicated microphthalmia, retrolental mass, and hyperechoic lenses. By color-flow Doppler imaging, blood flow was present in the retrolental mass of the right eye suggesting a persistent hyaloid artery.

Surgical results of persistent hyperplastic primary vitreous

PURPOSE

To evaluate the surgical success of patients with persistent hyperplastic primary vitreous (PHPV) and to identify preoperative indicators of visual outcome.

DESIGN

Noncomparative case series.

METHODS

The diagnosis of PHPV was made in 35 eyes of 27 patients from 1982 to 1994. In each case, anterior and/or posterior PHPV findings, preoperative testing, surgical procedures, and visual outcomes were documented. Twenty-nine of 35 eyes were managed surgically. Follow-up ranged from 2 months to 12 years.

RESULTS

Of the 35 eyes, 2 (5.7%) had strictly anterior PHPV, 8 (22.9%) had strictly posterior PHPV, and 25 (71.4%) had components of both anterior and posterior disease. Initial lensectomy and vitrectomy was performed in 24 eyes (68.6%). Surgery was withheld in four eyes secondary to severity of disease with an unrecordable visual-evoked potential (VEP). Reoperation rate was 32.3% for membrane reproliferation, glaucoma, vitreous hemorrhage, retinal detachment, or strabismus. Best-corrected final visual acuity ranged from 20/60 to no light perception. Six eyes (17%) maintained Snellen visual acuity despite posterior PHPV with some degree of retinal dysplasia.

CONCLUSIONS

Surgical treatment of PHPV can result in functional visual outcome despite posterior segment involvement. The degree of ocular malformation, however, will ultimately limit the amount of visual improvement. Preoperative testing, including VEP, may aid in determining surgical candidates.

Retinoblastoma and simulating lesions. Role of CT, MR imaging and use of Gd-DTPA contrast enhancement

The diagnosis of Rb can usually be made by clinical examination; however, patients should also be studied by CT and MR imaging to help determine the extent of the intraocular tumor, document intralesional calcification, confirm the diagnosis, and delineate orbital or intracranial involvement. These imaging techniques should aid the clinician in differentiating Rb from lesions that simulate Rb.

Coats' disease and persistent hyperplastic primary vitreous. Role of MR imaging and CT

Coats' disease is an idiopathic disorder in which telangiectatic and aneurysmal retinal vessels leak a lipoproteinaceous exudate, with consequent bullous retinal detachment. It is a diagnostic challenge, and CT and MR imaging provide valuable information to differentiate it from other pathologies, particularly from retinoblastoma. Typical, advanced Coats' disease shows on CT a denser substance posterior to the vitreous, which on MR is hyperintense on all pulse sequences. Contrast administration on both CT and MR might give slight linear enhancement at the boundary between vitreous and exudation. Persistent hyperplastic primary vitreous (PHPV) is a unilateral disorder in a microphthalmic eye, seen in full-term infants. PHPV rarely is bilateral in patients with Norrie's disease, Warburg syndrome, or patients with retinal dysplasia. Persistent fetal vasculature leads to fibrosis, resulting in elongation of the ciliary processes, retinal detachment, and spontaneous cataracts. The CT appearance in the disorder is quite variable; however, MR imaging may be superior in demonstrating the enhancing retrolental mass and the elongated ciliary processes.

Ultrasonographic diagnosis of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous in two dogs

Ultrasonography was performed on a Basset hound and a Doberman clinically suspected of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous. In both dogs, hyperechoic lenses with a triangular-shaped echodense structure retrolentally were visible, and a very thin hyperechoic strand was seen penetrating the anechoic vitreous from this retrolental tissue to the area of the optic nerve. Using color Doppler imaging, blood flow was evident in parts of the retina in both dogs. With power Doppler imaging there was blood flow in the lens and hyperechoic strand of the Basset hound on the first examination; whereas, on re-examination 5 months later, this was not found. Other abnormalities, such as retinal detachment, endophthalmitis, vitreous hemorrhage, microphthalmia, and posterior neoplasia could be excluded.

B mode ultrasonography--spectrum of paediatric ocular disease

BACKGROUND

Despite having appropriate sonographic equipment available many radiologists remain unfamiliar with B mode sonography of the eye.

OBJECTIVE

This article reviews the advantages and disadvantages of B mode sonography of the paediatric eye. We illustrate the spectrum of eye abnormalities occurring in paediatric practice and the sonographic appearance of clinical entities for which sonography is appropriate.

MATERIALS AND METHOD

We reviewed our experience of eye sonography within a paediatric radiology department over 8 years. A total of 212 sonographic examinations were performed on 206 eyes in 103 children, aged from 3 days to 16 years (mean 4.6 years).

RESULTS

Sonography was well tolerated by the children, was a very useful imaging modality and was the only diagnostic imaging modality required in 94%. Supplementary computed tomography (CT) was performed in ten of 206 eyes (5%) and magnetic resonance imaging (MR) was performed in two of 206 eyes (1%).

CONCLUSIONS

B mode sonography is a very useful imaging modality for suspected ocular or orbital pathology in children and is often the appropriate first line investigation following clinical evaluation. Radiologists familiar with sonography of the eye can provide valuable support to their ophthalmology colleagues.

Advances in neuroimaging of the visual pathways

PURPOSE

To provide a practical review for the ophthalmologist of advances in neuroimaging of the visual pathways.

METHODS

We reviewed recent advances in computed tomography, magnetic resonance imaging, and angiography that are applicable to visual pathways imaging.

RESULTS

For detailed ocular imaging, computed tomography complements ocular sonography for imaging of calcification, trauma, and masses. Magnetic resonance imaging may be helpful for localization and characterization of ocular masses in the setting of hemorrhage. For orbital imaging, computed tomography is most appropriate in the evaluation of suspected thyroid ophthalmopathy, infection, and trauma; otherwise, either computed tomography or magnetic resonance imaging is useful for detection and characterization of abnormality. For disorders affecting the sellar, retrochiasmal, and brainstem pathways, magnetic resonance imaging is the study of choice, except for acute hemorrhage, for which noncontrast computed tomography is preferable. Although magnetic resonance angiography has a role in the elective evaluation of cerebrovascular disease, conventional angiography is the definitive study for suspected aneurysm and for surgical planning.

CONCLUSIONS

A practical approach for selection of the most appropriate imaging modalities by the ophthalmologist is suggested on the basis of the anatomic location and type of disease suspected.

Orbital sonography in children

Orbital sonography with color-flow Doppler imaging is a relatively new technology with significant application in the pediatric patient. This review stresses the primary indications for pediatric ophthalmic ultrasound and also discusses those instances where the use of ultrasound supplements other imaging studies.

Magnetic resonance imaging versus computed tomography of leukocoric eyes and use of in vitro proton magnetic resonance spectroscopy of retinoblastoma

To evaluate the usefulness of magnetic resonance imaging (MRI) in the evaluation of leukocoric eyes, the authors studied 28 patients with either leukocoria or intraocular mass with a 1.5-tesla (T) MRI imager. Retinoblastomas were reliably distinguished from Coats' disease, toxocariasis, and persistent hyperplastic primary vitreous on the basis of MRI findings. Calcification cannot be reliably detected on MRI scans. Lesions elevated less than 4 mm may not be detected reliably by MRI at this time. Computed tomography (CT) can detect calcification with a high degree of accuracy. Retinoblastomas appeared as moderately hyperintense masses on T1- and proton-weighted MRIs. They became hypointense in T2-weighted MRIs. This MRI characteristic is similar to that of uveal melanoma. Intraocular calcification in children especially younger than 3 years of age is highly suggestive of retinoblastoma. In the diagnosis of retinoblastoma, MRI is not as specific as CT because of its lack of sensitivity in detecting calcification. However, MRI, because of its superior contrast resolution, offers more information in the differentiation of pathologic intraocular conditions responsible for leukocoria. The authors also describe their preliminary work of in vitro proton magnetic resonance spectroscopy of eyes with retinoblastoma and an eye with uveal melanoma in an 18-year-old black woman.

Diffuse infiltrating retinoblastoma

A young child was examined for unilateral hyphema of 1 month duration with a questionable history of blunt trauma. Ultrasonography was negative for tumefaction. Two months later the media cleared, revealing a diffusely abnormal retina. Computed tomography demonstrated a diffusely thickened posterior pole containing calcium. Histopathology of the enucleated globe was consistent with a diffuse infiltrating retinoblastoma. This is the first report of computed tomographic findings in diffuse infiltrating retinoblastoma.

Magnetic resonance imaging in the evaluation and differentiation of uveal melanoma

We evaluated 39 patients with intraocular disease by magnetic resonance imaging (MRI). Malignant uveal melanoma was considered the likely diagnosis in 25 patients. Seventeen patients underwent surgery, and the histopathologic diagnosis of melanoma was confirmed. The authors observed that uveal melanomas had characteristic MRI features consisting of a relatively high-signal intensity in T1-weighted images and a relatively low-signal intensity in T2-weighted images. These images reflected their inherently relative short T1 and T2 relaxation times. Choroidal lesions elevated more than 3 mm were well visualized on MRIs. MRI also proved valuable for differentiating uveal melanoma from associated subretinal effusion, choroidal hemangioma, choroidal metastasis, and hemorrhagic and serous choroidal detachments.

Computed tomography of Toxocara canis endophthalmitis

Many lesions, termed pseudogliomas, may mimic the appearance of retinoblastoma, both clinically and on computed tomography. The appearance of Toxocara canis endophthalmitis on computed tomography is presented. The role of computed tomography in the evaluation of patients presenting with leukokoria is discussed.

Computed tomography of the nonrhegmatogenous retinal detachment in the pediatric patient

Nonrhegmatogenous retinal detachments occur in the pediatric population secondary to other ocular disorders. The most important cause to identify is retinoblastoma. Computed tomography has proven to be the most reliable ancillary diagnostic test in this pediatric population. A series of eighty patients, presenting with nonrhegmatogenous retinal detachments, was examined. The role of computed tomography and characteristic clinical findings are discussed.

Computed tomography with histopathologic correlation in children with leukokoria

Computed tomography (CT) constitutes a major advance in noninvasive diagnostic investigation of children with leukokoria , especially where media opacities preclude adequate visualization of the posterior segment, and, performed in conjunction with other studies such as diagnostic ultrasonography, has significantly improved diagnostic accuracy. Although retinoblastoma, the commonest life-threatening cause of leukokoria , usually presents with characteristic CT findings of intraocular calcification, during extraocular extension, the orbital portions of the tumor are non-calcific and contrast dramatically with the intraocular portion. Currently CT is also the best available technique for diagnosis of trilateral retinoblastoma. Computed tomographic features of several types of pseudogliomas (a collective term for lesions commonly mistaken for retinoblastomas) are also discussed with histopathologic correlation. In persistent hyperplastic primary vitreous, a conical density in CT corresponded to detached and dysplastic retina. A high density layered opacity corresponded to subretinal blood. In Coats' disease and sclerosing endophthalmitis homogenous intraocular CT density corresponds to vitreous and subretinal exudates radiologically indistinguishable from non-calcific retinoblastoma. Long-standing retinal detachments in children occasionally presenting with leukokoria showed subtle homogenous intraocular densities on CT.

Computed tomography in choroidal detachment

Computed tomography proved valuable in localizing and differentiating serous or hemorrhagic choroidal detachment and scleral infolding. The mean attenuation values (CT numbers) in the region of fresh hemorrhagic choroidal detachment were 74 Hounsfield units (HU). The 90% confirmation limit of the mean was 55 to 84 HU. For serosanguineous choroidal detachment, the mean was 50 HU, with a 90% confirmation limit of 46 to 54 HU. For serous choroidal detachment the mean was 46 HU, with a 90% confirmation limit of 39 to 53 HU. Inflammatory choroidal detachment showed uveoscleral enhancement, which in cross section appeared as a ring (ring sign), and subchoroidal or intrauveal accumulation of fluid. Ocular hypotony produced the characteristic CT "umbrella sign."

Sclerosing endophthalmitis in children: computed tomography with histopathologic correlation

Three children with histopathologically diagnosed sclerosing endophthalmitis presumably secondary to Toxocara canis were studied by orbital computed tomography. The diffuse increased intraocular density present in the CT scans was indistinguishable from that observed in Coats's disease and non-calcifying retinoblastoma. Although retinoblastoma constitutes the major life-threatening cause of leukocoria in children, a number of other simulating conditions (pseudoglioma) can cause diagnostic confusion. In some cases of leukocoria it is exceedingly difficult to exclude the possibility of retinoblastoma without having to resort to enucleation. The availability of new non-invasive tests may make the distinction between retinoblastoma and pseudogliomas more easily attainable. Computed tomography (CT) has been shown to be of particular value in this regard by demonstrating intraocular calcification within retinoblastoma and rarely in lesions that stimulate it. CT may also be used to more appropriately plan therapy for children with retinoblastoma by assessing the status of the optic nerve and orbit. The exact role of CT in the evaluation of children with leukocoria, however, has not been completely established, since the computed tomographic features of several lesions that simulate retinoblastoma have not been described. The three most common causes of pseudoglioma are persistent hyperplastic primary vitreous, Coats's disease and sclerosing endophthalmitis. The latter entity when associated with a characteristic granulomatous inflammation is considered to represent the sequela of Toxocara canis infection of the eye. This report describes the computed tomographic findings in three cases of histologically diagnosed sclerosing endophthalmitis, presumably due to Toxocara canis.