Pentetreotide

indium In-111 pentetreotide, 111In-DTPA-D-Phe1-octreotide, 111In-DTPA-octreotide, OctreoScan; "somatostatin receptor scintigraphy" (SRS)

Oncology & imaging

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Note on this profile. In-111 pentetreotide was an approved diagnostic radiopharmaceutical for three decades and is now largely replaced by Ga-68 and Cu-64 somatostatin PET tracers. This page is kept for historical and interpretive context. There is no community or self-directed use.

1What it is

Pentetreotide is octreotide with a chelator (DTPA) attached to its N-terminal phenylalanine so it can carry indium-111. It was developed at Erasmus University, Rotterdam, in the late 1980s and became the first peptide-receptor imaging agent in routine use, approved in the US in 1994 as OctreoScan. For about 20 years it was the standard way to find and stage neuroendocrine tumours and to decide whether a patient would take up a somatostatin analogue.

It has now been superseded by Ga-68 DOTATATE (#201), Ga-68 DOTATOC (#202) and Cu-64 DOTATATE PET, which detect more lesions, finish in one visit instead of two, and deliver a lower radiation dose. Several guidelines now recommend PET over pentetreotide whenever available. Commercial production has been scaled back; the manufacturer announced discontinuation in some markets †.

2How it's thought to work

Pentetreotide binds SSTR2 with high affinity (less for SSTR5, little for SSTR1/3/4). After binding, the receptor-peptide complex is internalised and the indium stays in the cell, which is why delayed 24-hour images show higher tumour-to-background contrast as unbound tracer clears. Normal uptake is seen in spleen, kidneys, liver, pituitary, thyroid and bowel, and interpreters learn these patterns to avoid false positives. Resolution is limited to roughly 1–1.5 cm lesions with SPECT, compared with ~5 mm for PET.

The first-generation somatostatin receptor tracer, labelled with indium-111 for gamma-camera imaging. Largely replaced by the gallium-68 PET agents, which find smaller lesions.Schematic — not to scale

3What the research shows

Graded A/B

Detection of gastroenteropancreatic NETs

The landmark Rotterdam series of over 1,000 patients reported sensitivity of 80–100% depending on tumour type (highest for carcinoid, gastrinoma, paraganglioma; lowest for insulinoma at ~60%) (Krenning 1993, Eur J Nucl Med). Many subsequent prospective series confirmed detection of unsuspected metastases that changed management in roughly a quarter of patients (Lebtahi 1997, J Nucl Med). [1][2]

Graded A/B

Inferiority to Ga-68 PET

Prospective head-to-head comparisons consistently show Ga-68 somatostatin PET detects more lesions and more patients with disease: for example 95.1% vs 30.9% lesion-based sensitivity in one series (Buchmann 2007, Eur J Nucl Med Mol Imaging), and prospective data within NETTER-era trials (Sadowski 2016, J Clin Oncol). This is the evidence base for its retirement. [3][4]

Predicting response to somatostatin analogue and PRRT

Uptake grade on pentetreotide scans (the Krenning score) was used to select patients for PRRT and remains the language radiologists use for Ga-68 PET uptake today.

Graded B/C

Other uses (meningioma, lymphoma, sarcoidosis, Graves' orbitopathy)

Small series showed uptake in a range of SSTR-expressing tissues; none became routine indications.

4Reported side effects and interactions

Literature-reported

very well tolerated; adverse reactions (dizziness, flushing, headache, nausea, transient blood-pressure change) reported in fewer than 1% of patients. Transient hypoglycaemia has been reported in patients with insulinoma, since octreotide can suppress counter-regulatory glucagon; glucose is kept available. Radiation dose is higher than for a Ga-68 PET scan (effective dose ~12 mSv at 222 MBq vs ~4–5 mSv). Bowel activity can obscure abdominal lesions; laxatives are used before 24-hour imaging.

Community-reported

Community use. essentially none documented.

Interactions. therapeutic octreotide or lanreotide competes for binding and is stopped before the scan (short-acting 24–72 h, long-acting several weeks; practice varies). It should not be injected into TPN lines, as indium can form complexes with components of the solution.

Markers researchers commonly monitor

No treatment-related markers apply to a one-off diagnostic scan. Clinically relevant to the imaging context:

Marker	Why it's watched
Chromogranin A and 5-HIAA	the biochemical markers used alongside imaging to follow NETs.
Blood glucose	in patients with suspected insulinoma, because octreotide-based tracers can occasionally provoke hypoglycaemia.
Timing of somatostatin analogue dosing	recorded so that a negative scan is not misread when the receptor was blocked.
Krenning uptake score	the semi-quantitative grade on the scan itself, used to gauge eligibility for receptor-targeted therapy.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Not applicable to individuals. OctreoScan is a two-vial kit ( pentetreotide and indium-111 chloride) mixed in a hospital radiopharmacy, incubated at room temperature and quality-controlled for radiochemical purity before use. No calculator link is provided for this compound.

6Commonly studied alongside

Octreotide (#124) and lanreotide (the therapeutic analogues whose eligibility it assessed); DOTATATE (#201) and DOTATOC (#202), which replaced it; Tc-99m depreotide and Tc-99m HYNIC-TOC (#209), the technetium-based alternatives.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	FDA-approved 1994 (OctreoScan) for scintigraphic localisation of primary and metastatic SSTR-positive NETs; still listed, but commercial availability reduced †
European Union	Authorised nationally in many member states since the mid-1990s; supply being discontinued by the manufacturer †
United Kingdom	Licensed; largely replaced in the NHS by Ga-68 PET
Australia	TGA-registered historically; largely replaced by Ga-68 DOTATATE PET †
South Africa	Historically available; current registration and supply †
Sport (WADA)	Not listed

8Open questions

Whether any clinical niche remains where SPECT with pentetreotide is preferable to PET, beyond availability and cost in regions without PET access.
How to maintain comparability with decades of pentetreotide-based literature now that PET is standard.

9References

1Krenning EP et al. (1993). Somatostatin receptor scintigraphy with [111In-DTPA-D-Phe1]- and [123I-Tyr3]-octreotide: the Rotterdam experience with more than 1000 patients. Eur J Nucl Med. PubMed · DOI
2Lebtahi R et al. (1997). Clinical impact of somatostatin receptor scintigraphy in the management of patients with neuroendocrine gastroenteropancreatic tumors. J Nucl Med. PubMed
3Buchmann I et al. (2007). Comparison of 68Ga-DOTATOC PET and 111In-DTPAOC (Octreoscan) SPECT in patients with neuroendocrine tumours. Eur J Nucl Med Mol Imaging. PubMed · DOI
4Sadowski SM et al. (2016). Prospective study of 68Ga-DOTATATE PET/CT for detecting gastro-entero-pancreatic neuroendocrine tumors and unknown primary sites. J Clin Oncol. PubMed · DOI
5Bombardieri E et al. (2010). 111In-pentetreotide scintigraphy: procedure guidelines for tumour imaging. Eur J Nucl Med Mol Imaging. PubMed · DOI
6FDA. OctreoScan (kit for the preparation of indium In-111 pentetreotide) prescribing information. PubMed

References are being resolved to PubMed/DOI identifiers; links search PubMed for the citation until then.

† Being confirmed by our reviewers against current sources.

10Community

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Self-reported side effects Phase 2

Not enough data yet. 0 of the 50 members needed have logged this compound for 4+ weeks. We don't show anything below 50, so no one can be identified.

11Page history

31 Oct 2026Profile published — awaiting medical review

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