Imagerie des métastases intracrâniennes chez l’adulte

Cerebral staging of lung cancer: is one single contrast-enhanced T1-weighted three-dimensional gradient-echo sequence sufficient?

INTRODUCTION

Gadolinium-enhanced magnetic resonance imaging (MRI) is the gold standard for cerebral staging in thoracic oncology. We hypothesize that a minimalist examination, consisting of a single contrast-enhanced T1-weighted three-dimensional gradient-echo sequence (CE 3D-GRE), would be sufficient for the cerebral staging of nonsymptomatic lung cancer patients.

METHODS

Seventy nonsymptomatic patients (50 % men; 62 years ± 10.2) referred for cerebral staging of a lung cancer were retrospectively included. All underwent a standard 3 T MRI examination with T1, FLAIR, T2* GRE, diffusion, and CE 3D-GRE sequences, for a total examination time of 20 min. The sole CE 3D-GRE (acquisition time: 6 min) was extracted and blindly interpreted by two radiologists in search of brain metastases. Hemorrhagic features of potential lesions and relevant incidental findings were also noted. Discrepant cases were reviewed by a third reader. The full MRI examination and follow-up studies were used as a reference to calculate sensitivity and specificity of the sole CE 3D-GRE.

RESULTS

Thirty-eight point six percent (27 out of 70) of the patients had brain metastases. Performances and reader's agreement with the sole CE 3D-GRE sequence were excellent for the diagnosis of brain metastases (sensitivity=96.3 %, specificity=100 %, κ=0.91) and incidental findings (sensitivity=85.7 %, specificity=100 %, κ=0.62) but insufficient for the identification of hemorrhages within the metastases (sensitivity=33.3 %, specificity=85.7 %, κ=0.47).

CONCLUSIONS

In the specific case of lung cancer, cerebral staging in nonsymptomatic patients can be efficiently achieved with a minimalistic protocol consisting of a single CE 3D-GRE sequence, completed if positive with a T2* sequence for hemorrhagic assessment, thus halving appointment delays.

Pituitary Metastasis of Pancreatic Origin in a Dog Presenting with Acute-Onset Blindness

Pituitary metastases have rarely been recorded in dogs, and to date, none of those reported have been of pancreatic origin. MRI findings are available for only one of those cases. Herein the authors present an 11 yr old English springer spaniel diagnosed with pituitary metastasis of pancreatic origin with a 24 hr history of blindness and only a single lesion on MRI. Neurologic and ophthalmologic examinations localized the lesion to the optic nerves, optic tracts, or optic chiasm. MRI showed a single lesion characterized by a well-circumscribed pituitary mass with extrasellar extension, causing compression of the optic chiasm. Signal intensity was unusual as enhancement could not be appreciated after contrast administration. The dog was euthanized without further diagnostic tests. Histopathologic examination revealed a poorly differentiated exocrine pancreatic carcinoma with widespread metastasis involving the pituitary gland. To the authors’ knowledge, this is the first such case reported in a dog. Pituitary metastases should be included as a differential diagnosis for dogs presenting with acute-onset blindness and for single brain masses affecting the pituitary gland.

Imaging characteristics of cavernous sinus cavernous hemangiomas

Cavernous hemangiomas occur rarely in the cavernous sinus and are difficult to diagnose preoperatively. The imaging of these lesions resembles other benign paracavernous lesions such as schwannomas and meningiomas. Profuse intraoperative bleeding may be encountered during surgical resection of these lesions. A preoperative diagnosis is therefore important to alert the surgeon. We report on the imaging characteristics of two different histopathological types of cavernous sinus cavernous hemangiomas and the use of contrast-enhanced MRI, diffusion-weighted MRI and magnetic resonance spectroscopy in the differential diagnosis of these lesions.

[Brain metastasis of breast cancer; imaging evaluation]

CNS involvement in breast cancer modifies the prognosis and the treatment of the disease. Imaging plays a leading role for the diagnosis, the pretherapeutic assessment and the follow-up. MRI is the most sensitive modality for the detection of infraclinic lesions, reported in about 15% of metastatic breast cancers. In addition to conventional MR study, diffusion MR, perfusion MR and spectroscopy have a diagnostic value with specificity of more than 95%; 3D study is required if neurosurgical resection or stereotactic radiosurgery is contemplated. The use of new drugs in clinical trials needs a precise and accurate follow up to assess their usefulness; appreciation of the response is based on the precise measure of the number of targets and of their size; The WHO and recently the RECIST have established the guidelines for measurement of the tumoral targets and to assess the response to treatments. Brain modifications related to surgery or stereotactic radiosurgery are well studied by MRI.

[Management of brain metastases from non-small cell lung carcinoma]

INTRODUCTION

In France, approximately 30,000 new patients per year develop brain metastases (BM), most of them resulting from a lung cancer.

STATE OF THE ART

Surgery and radiosurgery of all the BM must be considered when possible. In other cases, whole brain radiotherapy remains the standard of care.

PERSPECTIVES

The role of chemotherapy, poorly investigated so far, should be revisited.

CONCLUSION

This review focused on BM secondary to a non-small cell lung carcinoma.

Presumed primary uveal melanoma with brain extension in a dog

A 13-year-old, female, mixed, cocker spaniel was examined for a unilateral exophthalmia and protruding mass in episcleral region of the right eye. Mode B ocular ultrasonography revealed a mass extended intraocular from anterior chamber to posterior pole without evidence of extraocular extension. A presumptive diagnosis of melanocytic tumour was made. A complete blood count and chemistry and thoracic radiographs did not show any abnormal changes. The recommended treatment was enucleation, and melanocytic nature of the tumour was confirmed by immunohistochemistry. Three months after surgery, the animal showed a status epilepticus refractory to treatment. Computed tomographic examination of the brain revealed changes compatible with a tumour. Cerebrospinal fluid analysis was normal. Because of the poor clinical prognosis, the owners elected to have the dog euthanased.