Inferior petrosal sinus sampling

Case contributed by Frank Gaillard


ACTH dependent Cushing's syndrome and congestive cardiac failure. CT of the chest, abdomen and pelvis demonstrates no focal abnormality.

Patient Data

Age: 70 years
Gender: Female

MRI pituitary


Two 3-millimeter areas of delayed enhancement are seen in the pituitary gland, one on the right just posterior to the level of the stalk and the other more centrally at the same level. The pituitary stalk is midline. The optic chiasm and cavernous sinuses are uninvolved, with normal cavernous carotid flow voids.


Two possible microadenomas. Whether both of these are microadenomas and if so whether both are functional is uncertain.

Inferior petrosal sinus sampling


Bilateral groin punctures were performed and 5 french guiding catheters passed up the IVC, through the right atrium and SVC into the internal jugulars to the base of skull.

Injection of contrast retrogradely opacified the inferior petrosal sinuses which were entered with micro-catheters (right, left) placed equidistant from the pituitary fossa, their position was confirmed with further injections of contrast. Contrast also outlines the sigmoid sinus and transverse sinus.

Following this simultaneous sampling of each microcatheter and the peripheral venous blood (via the groin sheath) was performed pre and post-administration of corticotropin-releasing hormone (CRH).

The venous ACTH levels obtained from the right and left petrosal sinuses and peripheral blood are as follows (00:00 = baseline, other times are in minutes post CRH administration):

  • 00:00 right perosal sinus            14.7
  • 00:02 right perosal sinus             243
  • 00:05 right perosal sinus             139
  • 00:10 right perosal sinus            93.0
  • 00:15 rigth perosal sinus            58.4
  • 00:00 left perosal sinus             8.06
  • 00:02 left perosal sinus             81.7
  • 00:05 left perosal sinus             81.3
  • 00:10 left perosal sinus             11.5
  • 00:15 left perosal sinus             8.50
  • 00:00 peripheral                     1.40
  • 00:02 peripheral                     1.51
  • 00:05 peripheral                     1.43
  • 00:10 peripheral                     2.53
  • 00:15 peripheral                     3.29

These results are consistent with a pituitary microadenoma, most likely in the right side of the gland. 

Case Discussion

On the basis of the IPSS and MRI this patient went on to have an exploratory transphenoidal hypophysectomy. Although histological proof of a microadenoma was not achieved, the patient became biochemically normal following surgery and their ACTH levels returned to normal. 

At 18 months follow up remains well with normal pituitary function. 

Case courtesy of A/Prof Peter Mitchell, Royal Melbourne Hospital

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