Pituitary gland. Variable signal intensities on MRI. A pictorial essay

The anterior pituitary gland may exhibit high signal on T1-weighted (T1w) images and/or low signal on T2-weighted (T2w) images in several normal and pathological states. High T1w signal may be seen in normal fetuses, neonates, and in pregnant and postpartum women. It may also occur in Rathke's cleft cyst, craniopharyngioma, subacute hemorrhage, manganese deposition, melanoma, dermoid, and lipoma. Low T2w signal may be seen in hemorrhage, calcification, cystic lesion, hemochromatosis, melanoma, and vascular lesions. These are described and illustrated.

MR of post traumatic spinal cord lesions. Unexpected improvement of hemorrhagic lesions

Fifteen patients who sustained spinal cord trauma were evaluated by MR within 72 hours of injury. Nine patients had hemorrhagic and six had nonhemorrhagic traumatic spinal cord lesions. Three patients with hemorrhagic and all six patients with nonhemorrhagic lesions showed some degree of neurological improvement on follow-up examinations. In two of the three patients with hemorrhagic lesions who improved, the hemorrhage was extensive. This supports the observation that hemorrhagic lesions are not always associated with a poor clinical outcome.

Demyelinating and gliotic cerebellar lesions in Langerhans cell histiocytosis

PURPOSE

To describe the involvement of the cerebellum by a gliotic and demyelinating process in Langerhans cell histiocytosis.

METHODS

A retrospective analysis of all (N = 30) cases of Langerhans cell histiocytosis followed at our institution since 1975 yielded four patients with CT and/or MR evidence of cerebellar abnormalities.

RESULTS

Four patients manifested strikingly similar findings of symmetric nonenhancing hypodensities in the dentate nuclei region of the cerebellum, which were hypointense on short-repetition-time/short-echo-time MR and hyperintense on long-repetition-time/long-echo-time MR. Biopsy in one patient yielded areas of demyelination, cell loss, and gliosis without histiocytic infiltration.

CONCLUSION

Langerhans cell histiocytosis involves the cerebellum in a specific and poorly understood manner. Lesions on imaging may precede clinical findings by years. Lesions may occur in patients who have never experienced radiation therapy and may act as a marker for eventual central nervous system deterioration.

Cystic meningiomas: MR characteristics and surgical correlations

PURPOSE

To describe the MR appearance of cystic meningiomas, and to correlate the MR appearance with the surgical and neuropathologic findings.

METHODS

Eight patients with cysts associated with meningiomas were studied on a 1.5-T MR system. Unenhanced sagittal T1- and axial T2-weighted images were obtained in all patients. Axial and coronal gadopentetate dimeglumine-enhanced T1-weighted spin-echo images were obtained in seven patients. Additional sagittal T1-weighted spin-echo contrast-enhanced images were obtained in four patients.

RESULTS

The cystic components were intratumoral and eccentric in two cases, intraparenchymal in one case, and extraparenchymal (trapped cerebrospinal fluid) in five cases. Cyst wall enhancement was present in two of seven cases performed with intravenous gadopentetate dimeglumine. There was no correlation between cyst signal intensity and cyst content. A preoperative diagnosis of cystic meningioma was possible in all eight cases.

CONCLUSIONS

MR demonstrates the extradural location of the tumor and its cystic component, correlates well with the surgical presentation and the neuropathologic results, and allows the preoperative diagnosis of cystic meningioma based on the MR findings. Division into three types of cysts aids the neurosurgeon, who must decide whether total resection is feasible. To obtain total resection and reduce the risk of recurrence with an intratumoral cyst, the surgeon must ensure that the plane of resection is in fact between the thin enhancing membrane of the tumor cyst and the adjacent arachnoid. In cases in which the cyst is trapped cerebrospinal fluid or intraparenchymal in location, the cyst wall adjacent to or within the brain parenchyma is not included in the resection.

Paradoxical ventricular enlargement after successful shunting

We present two cases of ventricular obstruction in which shunting of intracranial cysts resulted in the unexpected finding of ventricular enlargement. By imaging criteria this suggested shunt malfunction [corrected]; however, the clinical presentation dramatically improved. The probable mechanism for this diagnostic pitfall is discussed.

Proboscis lateralis with associated orbital cyst: detailed MR and CT imaging and correlative embryopathy

Proboscis lateralis is a rare craniofacial malformation. We present a case in a 1-week-old male infant, describe the clinical and imaging findings, and discuss the pertinent embryology. MR and CT proved to be complementary: CT provided anatomic detail in bone, defined the nasal cavity, and aided in determining the relationship of the proboscis and orbit; MR clarified the relationship of the proboscis to the orbit and skull base, and the relationships of normal brain to the dysplastic ethmoid centers.

Use of T1-weighted MR imaging to differentiate between primary polydipsia and central diabetes insipidus

PURPOSE

To investigate the value of MR in differentiating patients with primary polydipsia, who have an intact neurohypophyseal system, from those with central diabetes insipidus, who have impaired synthesis and/or release of vasopressin.

METHODS

Eighteen patients with clinically significant hypotonic polyuria were diagnosed endocrinologically as having primary polydipsia or diabetes insipidus (central or nephrogenic). These patients, and 92 patients without sellar disease, were then imaged with 1.5-T, T1-weighted, thin sagittal sections without gadolinium contrast.

RESULTS

Normal hyperintense signal of the neurohypophysis was present in 90 of 92 patients without sellar disease. The signal was also present in all six patients with primary polydipsia. In contrast, the hyperintense signal was absent in all eight patients with central diabetes insipidus. Three of the four patients with nephrogenic diabetes insipidus also had an absent hyperintense signal.

CONCLUSION

T1-weighted MR may prove important in differentiating patients with central diabetes insipidus from those with primary polydipsia.

Primary thalamic and caudate hemorrhage in term neonates presenting with seizures

Two previously well term neonates who presented with seizures are described: one with thalamic hemorrhage and the other with thalamic and caudate hemorrhage. These 2 patients were the only neonates found with thalamic hemorrhage in a review of 54 term infants with intracranial hemorrhage at The Hospital for Sick Children over a 10 year period (1976-1986). Partial seizures occurred at 5 and 7 days after birth and were easily controlled. Prognosis was generally good in these 2 patients, as well as in 4 previously reported patients.

Lumbar and thoracic spine pain in the athlete: radiographic evaluation

A comprehensive but basic and updated systematic radiographic approach to various pain-producing thoracolumbar diseases is presented. The advantages and limitations of available diagnostic modalities are discussed in relation to the clinically considered etiologies.

Headache in the athlete and radiographic evaluation

A deliberate attempt is made to stress the nonspecificity of headache and the complexity of its work-up. The choice of radiographic studies for its evaluation should be governed by the strongly considered etiology. This article deals with the most likely causes of headaches in an athlete. The merits and limitations of currently available radiographic modalities to detect headache-producing diseases are broadly discussed.

Intravenous digital subtraction angiography by peripheral injection

We describe a technique for performing intravenous digital subtraction arteriography by peripheral injection and review our experience of 504 studies in 469 patients. The technique gave adequate opacification for anatomical definition of vessels in 93% of patients studied and was suitable for studies of the pulmonary arteries and left ventricle as well as the major systemic arteries. The chief causes of failure were impaired cardiac performance (2.4%) and poor patient cooperation (1.4%). Premature termination was caused by angina pectoris in 1.6% of our cases. These limitations apply also to central venous injection.

Prolapse of an ectopic ureterocele into both urethra and ipsilateral orthotopic ureter

Ectopic ureteroceles frequently prolapse into the urethra. Inversion of ureteroceles into their own ureters has also been described. This patient showed a ureterocele which not only prolapsed into the urethra but also into the ipsilateral orthotopic ureter. We have not seen nor found a description of prolapse of a ureterocele into the ipsilateral orthotopic ureter.

Opportunistic gastritis in graft-versus-host disease

Two patients underwent bone marrow transplantation and subsequently developed graft-versus-host disease. Barium examination showed a gross nodular pattern in the stomach in one patient, an appearance not previously described. Both patients developed characteristic changes in the small bowel and in one the colon was also affected. The dramatic rise in the patient's cytomegaloviral titers (CMV) and the presence of viral inclusion bodies in gastric cells suggest that the changes in the stomach may be due to a CMV gastritis.

Computed tomographic diagnosis of pulmonary sequestration

Two cases of pulmonary sequestration demonstrated by CT scans of the chest are described. In one, CT demonstrated the anomalous artery. This finding may obviate the need for angiography when surgery is not contemplated.

[Renal angiomyolipoma in computer tomography]

Renal angiomyolipoma ia a rare benign lesion. It commonly presents with features suggestive of renal cell carcinoma when unilateral and solitary. It may mimic polycystic kidneys when bilateral and multiple. Angiomyolipomas with a high fat content are easily detected by computed tomography. Preoperative diagnosis of the lesion is possible and may help to obviate nephrectomy.

[Myelolipoma of the adrenal gland in whole-body computed tomography. Report on 2 histologically confirmed cases with clinic-radiological correlations]

Myelolipomas are rare non-functioning benign lesions. They occur almost exclusively in the adrenals and are usually small and asymptomatic. We report two cases of unusually large symptomatic myelolipomas of the adrenal which were examined by urography, ultrasound, angiography and computed tomography (CT). A review of the literature of 25 similar cases is presented with a discussion of the pathogenesis. Diagnostic features of an adrenal myelolipoma are (1) a non-functioning, (2) radiolucent, (3) solid and (4) avascular mass arising from the adrenal. With CT the preoperative diagnosis becomes possible by assessing the fat contents, tumor alignment and lack of invasiveness.