Unilateral cochlea sparing in locoregionally advanced head and neck cancer: a planning study.

BACKGROUND: Cochlea sparing can reduce late ototoxicity in head and neck cancer patients treated with cisplatin-based radiochemotherapy. In this situation, a mean cochlear dose (MCD) constraint of 10 Gy has been suggested by others based on the dose-effect relationship of clinical data. We aimed to investigate whether this is feasible for primary and postoperative radiochemotherapy in locoregionally advanced tumors without compromising target coverage. PATIENTS AND METHODS: Ten patients treated with definitive and ten patients treated with adjuvant intensity-modulated radiotherapy (IMRT) and concurrent chemotherapy were investigated. The cochleae and a planning risk volume (PRV) with a 3 mm margin were newly delineated, whereas target volumes and other organs at risk were not changed. The initial plan was recalculated with a constraint of 10 Gy (MCD) on the low-risk side. The quality of the resulting plan was evaluated using the difference in the equivalent uniform dose (EUD). RESULTS: A unilateral MCD of below 10 Gy could be achieved in every patient. The mean MCD was 6.8 Gy in the adjuvant cohort and 7.6 Gy in the definitive cohort, while the non-spared side showed a mean MCD of 18.7 and 30.3 Gy, respectively. The mean PRV doses were 7.8 and 8.4 Gy for the spared side and 18.5 and 29.8 Gy for the non-spared side, respectively. The mean EUD values of the initial and recalculated plans were identical. Target volume was not compromised. CONCLUSION: Unilateral cochlea sparing with an MCD of less than 10 Gy is feasible without compromising the target volume or dose coverage in locoregionally advanced head and neck cancer patients treated with IMRT. A prospective evaluation of the clinical benefit of this approach as well as further investigation of the dose-response relationship for future treatment modification appears promising.

Arteriovenous malformations of the brain. II: Current concepts and treatment.

In this second of a two-part article, the treatment of arteriovenous malformations (AVMs) of the brain is discussed. The natural course of these lesions, which is treacherous, must be balanced against the risk-effectiveness of various therapies. Radiotherapy rarely abolishes these lesions and subjects the patient to the risk of radionecrosis and rebleed from the AVM. Embolization, which involves the placement of small spheres into the lesion under radiographic control, is a moderately safe procedure that can reduce the size of, but rarely eliminates, these malformations. Embolization, however, has been used effectively in preparing the lesion for excision. The techniques of contemporary surgery and the results of treatment of a large number of AVMs are discussed.

Arteriovenous malformations of the brain. I: Current concepts and treatment.

Arteriovenous malformations (AVMs) of the brain are uncommon congenital lesions, causing symptoms in the middle decades of life. Neurosurgical and neuroradiological techniques have been developed to deal effectively with these lesions, in many instances resulting in a cure. This first part of a two-part article details the important anatomic aspects of these lesions, symptoms, and radiographic considerations. The largest group of lesions discussed here, the AVMs, vary in size but are usually large, involving important areas of the cortex and white matter with a complex array of arterial to venous shunts. Their most common initial symptoms are due to hemorrhage or seizure. The use of the computerized tomographic scan has often resulted in the unexpected diagnosis of these lesions. However, angiography remains the paramount method of defining these lesions.

The radiology of pituitary adenomas.

The radiologic management of pituitary adenomas has changed considerably over the last decade. With the development of sophisticated new technologies, diagnostic testing has evolved from pneumoencephalography to pluridirectional tomography, computed tomography, and currently magnetic resonance imaging. This article discusses these dramatic changes and demonstrates the present state-of-the-art and utility of radiologic methods in diagnosing microadenomas and macroadenomas and in differentiating these lesions from parasella lesions.

Value of computed tomographic scanning in patients with growth hormone deficiency.

In 18 of a series of 23 patients with growth hormone deficiency, computed tomographic scanning demonstrated a markedly small sellar volume. In four of the remaining five patients, the sella was enlarged. The cause of the enlargement was readily identifiable. Computed tomographic scanning of the sella appears to provide valuable supportive evidence of hypopituitarism.

The value of metrizamide CT cisternography in the management of cerebral arachnoid cysts.

Arachnoid cysts may or may not communicate with the cerebrospinal fluid pathways. Patterns of communication were studied in six patients, using metrizamide computed tomography (CT) cisternography, ventriculography, and cystography. Two types of cysts were found: one with free communication with the cerebrospinal fluid pathways and one with restricted communication. This information can be useful in the surgical management of the cysts. When the cysts freely communicate wih the ventricles, ventricular shunting is the appropriate therapy, whereas when the cysts are noncommunicating, direct shunting of the cyst is indicated.

Hemimegalencephaly: a longitudinal MR study.

An infant with hemimegalencephaly was studied with MR at 5 days and again at 10 months of age. The initial scan showed an abnormally large left cerebral hemisphere. At the age of 10 months, the left cerebral hemisphere was smaller than the right--an apparent left-sided micrencephaly caused by normal growth of the right hemisphere and arrested growth of the left. The age of imaging of a patient with hemimegalencephaly can be important if the correct diagnosis is to be made.

The bright pituitary gland--a normal MR appearance in infancy.

Signal intensities of the pituitary gland were measured on T1-weighted sagittal MR images of 25 patients younger than 20 years old. We found that the signal intensities in the eight patients who were 8 weeks old or younger were higher (shorter T1) than those in the 17 older patients. We also noted a difference in the signal intensities across the pituitary gland, the signal being higher in the posterior part of the gland than in the anterior part. We attribute the high signal intensities to the rapid intrauterine pituitary growth, so that at term pituitary protein synthetic activity is at a maximum. Possibly, an increase in the bound fraction of the water molecules of the gland may also be present in the neonatal pituitary as compared with the older gland, but this remains to be proved. The higher signal in the posterior pituitary gland may be due to lipid in the pituicyte cells of the posterior pituitary gland.

MR evaluation of neurovascular lesions after endovascular occlusion with detachable balloons.

Three patients with surgically inaccessible giant carotid aneurysms/pseudoaneurysms and one patient with carotid cavernous fistula had endovascular occlusion with detachable silicone balloons filled with Cholografin. MR was performed before the procedures in three cases and again 18 hr to 44 days after embolization in all four cases. The age-related changes of arterial thrombi, as well as the optimal timing and value of different pulse sequences in the noninvasive follow-up, were evaluated. Arterial thrombi have some characteristics in common with intracerebral hematomas, being isointense on T1-weighted spin-echo images during acute phase and subsequently acquiring hyperintense signals on both T1- and T2-weighted spin-echo images during the subacute and chronic phases. Additional observations are that (1) hyperacute (less than 24 hr old) thrombus is hyperintense on T2-weighted spin-echo sequences; (2) hemosiderin is less conspicuous in chronic intraluminal thrombi than in intracerebral hematomas of comparable size; and (3) thrombosis is initiated at a site remote from the apex of the aneurysm and then progresses centripetally. The Cholografin-filled balloon is hypointense to gray matter on T1-weighted spin-echo images and isointense to both hyperacute and chronic thrombus on T2-weighted spin-echo images. The optimal timing and sequence for MR follow-up of a thrombosed aneurysm with conventional spin-echo technique is beyond 7 days on T1-weighted spin-echo images. The in vivo appearance of Cholografin-filled silicone balloons does not change appreciably on T1- and T2-weighted spin-echo sequences up to 6 weeks if filled according to the manufacturer's specification.

The clinical significance of hindbrain herniation and deformity as shown on MR images of patients with Chiari II malformation.

This study investigates whether the degree of brainstem herniation and the nature of the cervicomedullary deformity seen on sagittal plane MR images correlates with the clinical syndrome in patients with the Chiari II malformation. The amount of brainstem herniation was assessed by relating the position of the midbrain and pons to the sella turcica and the anterior lip of the foramen magnum, respectively. The cervicomedullary deformity was graded into degrees of increasing severity. We found that the neurologic status of these children was not affected by either the amount of herniation or the characteristics of the cervicomedullary deformities. Because of these findings, we believe that other factors, such as disorganization of the brainstem nuclei, may be the likely cause for the breathing and swallowing difficulties experienced by children with the Chiari II malformation.

Superselective arterial BCNU infusion in the treatment of patients with malignant gliomas.

Retinal and CNS toxicity have been reported with infraophthalmic infusion of BCNU in the treatment of patients with malignant gliomas. It is known, however, that the CNS toxicity can be reduced if the BCNU is dissolved in dextrose in water. This article describes the results from 15 patients who received 42 courses of BCNU administered by supraophthalmic internal carotid, middle cerebral, or posterior cerebral artery infusions. None of the patients developed leukoencephalopathy as demonstrated by CT scanning. The average reduction in tumor volume was 36%, and the median survival time from the date of diagnosis was 73 weeks. These values are comparable to those of a previous group of 20 patients treated with infraophthalmic infusions, with the exception that none of the patients in the present group developed retinal damage.

MR imaging of middle cranial fossa arachnoid cysts: temporal lobe agenesis syndrome revisited.

MR studies in eight patients with extraaxial arachnoid cysts in the middle cranial fossa were reviewed in order to identify any associated structural defect in the ipsilateral temporal lobe. The study was prompted by the original theory that agenesis of the temporal lobe is the primary factor in the development of these cysts. Authors of subsequent studies proposed that the cysts are a consequence of embryological malformation of the meninges only and that the adjacent temporal lobe is compressed. Our findings suggest that middle cranial fossa cysts are associated with temporal lobe hypogenesis, and also that compression of the temporal lobe is an infrequent accompaniment.

A cliniconeuroradiologic approach to third cranial nerve palsies.

Sixty-three patients with third cranial nerve palsies (CNPs), either isolated (31) or in association with other neurologic deficits (32), underwent neuroophthalmologic and neuroradiologic evaluation. Discrepancies between the clinical and radiologic evaluations were analyzed and useful clinical presenting symptoms were identified. Microvascular infarction secondary to diabetes mellitus and/or hypertension was the most common cause in patients with isolated third CNP, and extensive neuroradiologic evaluation is not indicated in this subgroup. The overall diagnostic yield of high-resolution CT for isolated third CNPs was low (30%), but improved to 60% if diabetes and hypertension were excluded. However, CT was highly sensitive (90%) in those patients with third CNPs associated with additional neurologic deficits. The status of the pupil in and of itself cannot be the sole determinant as to whether angiography is indicated to exclude an aneurysm. Careful ophthalmologic observation and relating the severity of pupillomotor dysfunction to extraocular ophthalmoplegia is mandatory to determine the logical sequence of radiologic evaluation. Retroorbital pain taken in isolation is a nonspecific presenting symptom and has differential diagnostic value only if it is correlated temporally with the onset of third CNP and the presence or absence of additional cranial nerve deficits.

CT and MR appearance of the brain in two children with molybdenum cofactor deficiency.

Imaging findings in two children with molybdenum cofactor deficiency included, in one, diffuse low attenuation on CT in cerebral white matter, caudate nuclei, and thalami soon after birth. MR in both patients later demonstrated progressive widening of the sulci, ventricles, and cisterna magna, and loss of brain volume. MR finally showed cessation of myelination at 31 months and 16 weeks of age.

Analysis of cerebrospinal fluid flow waveforms with gated phase-contrast MR velocity measurements.

PURPOSE: To analyze the characteristics of normal cerebrospinal fluid (CSF) flow waveforms and to relate them to the arterial input and venous output flow waveforms in healthy volunteers. METHODS: Cine phase-contrast MR was obtained in 17 volunteers. The temporal velocity information from the cervical pericord CSF spaces, basal cisterns, and aqueduct, as well as the internal carotid and vertebral arteries and internal jugular veins, were plotted as waveforms. The waveforms were analyzed for configurations, amplitudes, and temporal patterns. In four volunteers the reproducibility of the precord CSF flow waveforms was examined on different days. In three volunteers the effect of jugular venous compression on the precord and aqueductal CSF flow waveforms was also evaluated. RESULTS: (a) Distinct and reproducible configurational features were observed in the CSF flow waveforms. Jugular venous compression produced elevation of the disatolic slope of the precord waveforms. (b) The amplitudes were variable. Jugular venous compression reduced the precord CSF velocities. (c) The systolic temporal parameters were less variable and more reproducible than the diastolic temporal parameters. Jugular venous compression resulted in delay in the systolic parameters of the precord waveforms. (d) Craniocaudal and caudocranial postcord CSF flow occurred either simultaneous with or earlier than the precord CSF flow. Pericord CSF flow in either direction preceded that in the cisterns and in the aqueduct. (e) A significant temporal relationship was noted in the precord space between the time of the R wave to the maximum velocities and the arterial flow. CONCLUSION: CSF flow waveform analysis seems to be a reliable, reproducible, and sensitive method for assessing the CSF dynamics.

Difficulties in diagnosing congenital posterior fossa fluid collections after shunting procedures.

The differential diagnosis of retrocerebellar fluid collections in infants is important because of the prognostic implications. Usually the diagnoses are easy; however, shunting of the lateral ventricles or of the fluid collections may alter the appearance of the lesions, precluding accurate diagnosis. Under such circumstances a careful study of all the sequential radiologic studies is necessary.

Chiari I malformations: assessment with phase-contrast velocity MR.

PURPOSE: To assess movement of the medulla, tonsils, and upper cervical cord as well as that of the posterior fossa cerebrospinal fluid pathways in both normal subjects and those with Chiari I malformations. METHODS: Nine healthy volunteers and eight patients with Chiari I malformations were examined with phase-contrast cine MR. With a region-of-interest cursor, the directions and intensities of the brain and cerebrospinal fluid were assessed and intensity-versus-time graphs generated. RESULTS: Cerebrospinal fluid flow patterns of the patients with Chiari I malformations were normal except for absence of valleculla flow. In addition, increased velocities (10 times normal) of the tonsils of all patients with Chiari I malformations together with posterior movement of the medulla (rather than the expected anterior movement seen in volunteers) occurred. CONCLUSIONS: Increased velocities of the tonsils may be the result of the carotid systolic pulse being delivered to a structure (the tonsil) without the normal surrounding cerebrospinal fluid, resulting in impact of the tonsils in the confined foramen magnum and a consequent caudocranial recoil. An alternative explanation would include the Bernoulli effect caused by the confined location of the tonsils. There may be a decrease in the peak tonsillar velocities after surgery.

Neuroradiologic evaluation of patients with acute stroke treated with recombinant tissue plasminogen activator. The rt-PA Acute Stroke Study Group.

PURPOSE: 1) To describe the effectiveness and safety of thrombolytic therapy in patients with acute atherothrombotic and embolic stroke and 2) to study the variables of the occlusion site as seen on the angiograms, the CT signs of early ischemia, the hyperdense middle cerebral artery sign (HMCAS), and the size of the infarcts as seen on the 24-hour CT scan. METHODS: Ninety-three of 139 patients with acute stroke were treated with intravenous tissue plasminogen activator (rt-PA). The initial disease and the effects of treatment were assessed with both CT and cerebral angiography. RESULTS: Recanalization of occluded arteries occurred in 32 patients and was more frequent in distal occlusions. In general, patients displaying recanalization tended to develop small infarcts and patients with a HMCAS tended to develop large infarcts. Patients with signs of early ischemia developed large infarcts. The presence of a HMCAS was 100% fic for an occluded artery, but only 27% sensitive. Hemorrhagic transformations occurred in the distribution of the occluded arteries in 32 patients. CONCLUSIONS: Emergency cerebral angiography, which can be carried out relatively safely, adds important information about the nature and extent of the arterial occlusions, and the recanalization efficacy of fibrinolytic therapy for patients with acute stroke. Fibrinolytic therapy can be carried out with a relatively low complication rate that still needs to be correlated with the clinical benefits of the treatment. Fibrinolytic therapy in the doses utilized in this study, is more effective with distal than with proximal carotid territory occlusions.

Segmental spinal dysgenesis.

Segmental spinal dysgenesis is characterized by focal agenesis or dysgenesis of the lumbar or thoracolumbar spine, with focal abnormality of the underlying spinal cord and nerve roots. Children are symptomatic at birth with lower limb deformities and neurological deficits that may be segmental. Myelography and computed tomography disclose hypoplastic or absent vertebrae and atrophic or absent neural elements adjacent to the bony deformity; the spinal column distal to the abnormality may be partially bifid, but is otherwise normal. Spinal ultrasonography was a helpful diagnostic adjunct in one patient. Surgery may be helpful in decompressing partially functioning spinal cord or nerve roots, but may exaggerate the tendency toward spinal instability. The embryology of this abnormality is not clear, but two children had other anomalies suggesting a spinal dysraphic syndrome, and its cause is probably related to a segmental maldevelopment of the neural tube.

Intracarotid chemotherapy with 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) in 5% dextrose in water in the treatment of malignant glioma.

After radiotherapy, 20 patients, 18 with documented progression of malignant glioma and 2 with Grade II astrocytoma, received a total of 52 courses of intracarotid 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) at a dose of 150 mg/m2 dissolved in 5% dextrose in water. The patients were treated at 6-week intervals for a maximum of five courses of chemotherapy per patient. Response to treatment was analyzed on computed tomographic scans by measuring the volume of the enhancing tumor and any central low density. From these data, tumor doubling times ranging from 110 to 968 days were obtained. An 11 to 60% reduction in enhancing tumor volume was noted in 8 patients, 2 of whom had a greater than 50% decrease in tumor volume. One patient had no change in tumor volume 110 weeks after the initiation of BCNU chemotherapy. Four patients had tumor in more than one vascular territory; tumor growth was arrested in the perfused territory, but continued in the nonperfused area. In 1 of the 4 patients, tumor also grew along a shunt catheter tract and spread over the surface of the ipsilateral hemisphere. One patient developed clinically asymptomatic leukoencephalopathy after five courses of BCNU. Two patients had postradiation leukoencephalopathy before BCNU treatment. Seventeen patients had peritumoral low density with mass effect after BCNU; thus, the true incidence of BCNU-related leukoencephalopathy could not be determined. All patients experienced transient unilateral orbital pain during the infusion and scleral erythema that lasted for several hours afterward. Loss of vision was noted in 2 patients, although it seemed to be related to the therapy in only 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)