Mechanism of action of octreotide in acromegalic tumours in vivo using dynamic contrast-enhanced magnetic resonance imaging

Thozhukat Sathyapalan, Martin Lowry, Lindsay W. Turnbull, Chris Rowland-Hill, Stephen Atkin

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Context: Octreotide causes significant tumour shrinkage in patients with acromegaly but the exact mechanism of action is unclear in vivo. Objective: To determine the mechanism of action of octreotide in vivo using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Design: Five patients with acromegaly were treated with octreotide as primary medical therapy. DCE-MRI was done at baseline and 24 weeks. Local ethical committee approval was granted. Setting: Study was done in a tertiary care centre. Patients: Five patients with newly diagnosed acromegaly were recruited. Intervention: Patients were started on subcutaneous octreotide and DCE-MRI was done on 0 and 24 weeks. Main outcome measures: Amplitude of contrast intake, exchange rate and maximum enhancement index of tumour tissue was compared before and after treatment. Results: Amplitude of contrast intake (9.87 ± 3.52 vs. 4.97 ± 1.96 P ≤ 0.05) and exchange rate (6.27 ± 1.57 vs. 1.63 ± 0.76 P value ≤ 0.01) were significantly higher at baseline in adenoma compared to normal pituitary tissue but was comparable to normal pituitary tissue after treatment. There was a significant decrease in amplitude of contrast intake and exchange rate which relates to functional vascularity of adenoma at 24 weeks compared to baseline (P-values 0.026 and 0.002 respectively) but there were no significant changes in the normal pituitary tissue. Conclusion: DCE-MRIin acromegalic tumours treated with octreotide showed a significant reduction in functional vascularity after octreotide therapy compared to baseline in pituitary adenomas. This supports the antiangiogenic action of somatostatin analogue therapy in vitro, but it remains unclear if this mechanism is important clinically in analogue pre-treatment reducing the effect of radiotherapy on these pituitary tumours.

Original languageEnglish
Pages (from-to)233-236
Number of pages4
JournalPituitary
Volume10
Issue number3
DOIs
Publication statusPublished - Sep 2007
Externally publishedYes

Fingerprint

Octreotide
Magnetic Resonance Imaging
Acromegaly
Neoplasms
Pituitary Neoplasms
Adenoma
Therapeutics
Somatostatin
Tertiary Care Centers
Radiotherapy
Outcome Assessment (Health Care)

Keywords

  • Acromegaly
  • Angiogenesis
  • DCE-MRI
  • Dopamine agonist
  • Octreotide

ASJC Scopus subject areas

  • Endocrinology

Cite this

Mechanism of action of octreotide in acromegalic tumours in vivo using dynamic contrast-enhanced magnetic resonance imaging. / Sathyapalan, Thozhukat; Lowry, Martin; Turnbull, Lindsay W.; Rowland-Hill, Chris; Atkin, Stephen.

In: Pituitary, Vol. 10, No. 3, 09.2007, p. 233-236.

Research output: Contribution to journalArticle

Sathyapalan, Thozhukat ; Lowry, Martin ; Turnbull, Lindsay W. ; Rowland-Hill, Chris ; Atkin, Stephen. / Mechanism of action of octreotide in acromegalic tumours in vivo using dynamic contrast-enhanced magnetic resonance imaging. In: Pituitary. 2007 ; Vol. 10, No. 3. pp. 233-236.
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abstract = "Context: Octreotide causes significant tumour shrinkage in patients with acromegaly but the exact mechanism of action is unclear in vivo. Objective: To determine the mechanism of action of octreotide in vivo using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Design: Five patients with acromegaly were treated with octreotide as primary medical therapy. DCE-MRI was done at baseline and 24 weeks. Local ethical committee approval was granted. Setting: Study was done in a tertiary care centre. Patients: Five patients with newly diagnosed acromegaly were recruited. Intervention: Patients were started on subcutaneous octreotide and DCE-MRI was done on 0 and 24 weeks. Main outcome measures: Amplitude of contrast intake, exchange rate and maximum enhancement index of tumour tissue was compared before and after treatment. Results: Amplitude of contrast intake (9.87 ± 3.52 vs. 4.97 ± 1.96 P ≤ 0.05) and exchange rate (6.27 ± 1.57 vs. 1.63 ± 0.76 P value ≤ 0.01) were significantly higher at baseline in adenoma compared to normal pituitary tissue but was comparable to normal pituitary tissue after treatment. There was a significant decrease in amplitude of contrast intake and exchange rate which relates to functional vascularity of adenoma at 24 weeks compared to baseline (P-values 0.026 and 0.002 respectively) but there were no significant changes in the normal pituitary tissue. Conclusion: DCE-MRIin acromegalic tumours treated with octreotide showed a significant reduction in functional vascularity after octreotide therapy compared to baseline in pituitary adenomas. This supports the antiangiogenic action of somatostatin analogue therapy in vitro, but it remains unclear if this mechanism is important clinically in analogue pre-treatment reducing the effect of radiotherapy on these pituitary tumours.",
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