MRI Sella MRI with and without IV contrast using high-resolution pituitary or skull base protocols is preferred in the workup of suspected central diabetes insipidus and in the detection of abnormalities of the hypothalamic- neurohypophyseal axis, which may lead to failure of normal antidiuretic hormone release and transport. Thin- section T1-weighted images are used to directly identify typical T1 signal hyperintensity of normal neurosecretory granules; such a signal may be absent from the sella when an ectopic posterior pituitary gland is present or in long-standing diabetes insipidus. Traumatic etiologies, such as stalk transection or postoperative sella, can be characterized using thin-section T2-weighted images. MRI with and without IV contrast is especially useful for the detection and characterization of inflammatory lesions of the stalk and neoplastic invasion [23,82]. MRI with IV contrast may only be performed for use in operative guidance and should not be considered a first- line imaging test. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of diabetes insipidus. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of diabetes insipidus. CT Sella CT may provide useful information in the clinical setting of sudden onset of pituitary dysfunction by identifying a pituitary or suprasellar mass but is less sensitive than MRI for the detection of acute pituitary hemorrhage [16]. MRI is considered the optimal first-line test. Calcification seen on CT may help to clarify complicated cases of craniopharyngioma, which can occasionally be confused with hemorrhagic pituitary adenoma on MRI. While the use of IV contrast may help distinguish hemorrhage from enhancement, dual-phase imaging with and without IV contrast is not indicated as an initial imaging study.
Neuroendocrine Imaging. MRI Sella MRI with and without IV contrast using high-resolution pituitary or skull base protocols is preferred in the workup of suspected central diabetes insipidus and in the detection of abnormalities of the hypothalamic- neurohypophyseal axis, which may lead to failure of normal antidiuretic hormone release and transport. Thin- section T1-weighted images are used to directly identify typical T1 signal hyperintensity of normal neurosecretory granules; such a signal may be absent from the sella when an ectopic posterior pituitary gland is present or in long-standing diabetes insipidus. Traumatic etiologies, such as stalk transection or postoperative sella, can be characterized using thin-section T2-weighted images. MRI with and without IV contrast is especially useful for the detection and characterization of inflammatory lesions of the stalk and neoplastic invasion [23,82]. MRI with IV contrast may only be performed for use in operative guidance and should not be considered a first- line imaging test. Venous Sampling Petrosal Sinus There is no relevant literature regarding the use of venous sampling in the evaluation of diabetes insipidus. Radiography Sella There is no relevant literature regarding the use of radiography in the evaluation of diabetes insipidus. CT Sella CT may provide useful information in the clinical setting of sudden onset of pituitary dysfunction by identifying a pituitary or suprasellar mass but is less sensitive than MRI for the detection of acute pituitary hemorrhage [16]. MRI is considered the optimal first-line test. Calcification seen on CT may help to clarify complicated cases of craniopharyngioma, which can occasionally be confused with hemorrhagic pituitary adenoma on MRI. While the use of IV contrast may help distinguish hemorrhage from enhancement, dual-phase imaging with and without IV contrast is not indicated as an initial imaging study.