Imaging Guide · DOTATATE PET-CT

Ga-68 DOTATATE PET-CT: what to expect.

A sourced patient and clinician guide to Ga-68 DOTATATE PET-CT — the somatostatin receptor imaging that drives PRRT eligibility for neuroendocrine tumours. What it is, who needs it, how to prepare, what happens on scan day, what the Krenning score means, and how the report shapes the treatment plan.

Dr. Ishita B. Sen, MDDirector & Chief, Nuclear Medicine · FMRI

Published 14 May 2026

Reviewed by Dr. Dharmender Malik

12 min read

Last reviewed by Dr. Dharmender Malik on 14 May 2026 · this article reflects the published primary literature and current clinical practice at FMRI Gurugram.

Introduction

Ga-68 DOTATATE PET-CT is the imaging foundation of contemporary neuroendocrine tumour (NET) management. It detects somatostatin receptor type 2 (SSTR2) expression on tumour cells, which is both a diagnostic marker for NETs and the molecular target for peptide receptor radionuclide therapy (PRRT). Almost every meaningful treatment decision for a metastatic NET patient flows through a DOTATATE PET-CT: tumour staging, response assessment, and — critically — PRRT eligibility. This article is a sourced patient and clinician guide to what the scan is, how to prepare for it, what happens on the day, and how to read the report.

What is Ga-68 DOTATATE PET-CT?

AI Overview · short answer

Ga-68 DOTATATE PET-CT is a molecular imaging study that visualises somatostatin receptor type 2 (SSTR2) expression on cells throughout the body. A peptide (DOTATATE) that binds SSTR2 is labelled with the positron-emitting isotope gallium-68 (Ga-68); when infused intravenously, it concentrates in SSTR2-expressing tissues including normal pituitary, spleen, adrenals, and — importantly — well-differentiated neuroendocrine tumours. The PET camera detects the radioactive decay and the CT component provides anatomical localisation^[1].

Ga-68 DOTATATE PET-CT replaced earlier somatostatin receptor imaging (In-111 OctreoScan) starting in the mid-2010s. The advantages over OctreoScan include: better spatial resolution (sub-centimetre lesions visible), substantially shorter imaging time (60 minutes versus 24-48 hours), lower radiation dose to the patient, and the ability to perform same-day quantitative assessment using SUVmax measurement^[2].

Who needs a Ga-68 DOTATATE PET-CT?

The major indications for Ga-68 DOTATATE PET-CT in adults and children^[3]:

Initial staging of biopsy-confirmed well-differentiated NET — to map all sites of disease, particularly when CT/MRI findings are ambiguous.
Suspected NET with biochemical evidence — elevated chromogranin A or 5-HIAA with non-conclusive cross-sectional imaging.
Pre-PRRT eligibility confirmation — to confirm SSTR2 expression in the target lesions, calculate the Krenning score, and exclude SSTR-negative lesions.
Response assessment after systemic therapy — typically at 3-6 months post-treatment or earlier if clinical concern.
Restaging at clinical or biochemical progression — to identify new lesions or evolving heterogeneity.
Pheochromocytoma and paraganglioma — DOTATATE PET-CT is particularly useful in SDHx-mutated PPGL where MIBG uptake may be limited.
Pediatric neuroblastoma in selected contexts.

How to prepare for the scan

Patient preparation for Ga-68 DOTATATE PET-CT is straightforward^[4]:

Long-acting somatostatin analogue therapy — Octreotide LAR or lanreotide injections should generally be timed so that the scan is performed at least 4 weeks after the last injection (current EANM guidance — some experienced centres allow shorter intervals if clinically justified). Short-acting octreotide should be stopped at least 24 hours before scanning.
Fasting — Generally not required for DOTATATE PET-CT (unlike FDG PET-CT). Most centres allow normal eating and drinking before the scan.
Medications — Most other medications can continue normally; bring a current medication list.
Hydration — Adequate hydration with water is encouraged. Empty bladder before scan acquisition.
Clothing — Loose, comfortable clothing without metal (no zips, buttons, underwire). Most centres provide a hospital gown for the scan itself.
Bring — Prior imaging on disc/USB; recent biochemistry; pathology reports; current medication list; referral letter.

What happens on scan day

A typical Ga-68 DOTATATE PET-CT visit takes approximately 2-3 hours from arrival to departure^[5]:

Check-in and consent — paperwork, medication review, weight measurement.
Cannulation — a small IV cannula is placed, typically in the forearm or back of the hand.
Tracer injection — Ga-68 DOTATATE is injected intravenously, typical activity 150-200 MBq. The injection itself is painless (cold liquid through the cannula). Many patients describe a brief, mild sensation in the arm during injection.
Uptake period — Patients rest in a quiet room for approximately 60 minutes (typical range 45-90 minutes) while the tracer distributes through the body. Reading, listening to music, or light conversation is fine.
Voiding — Patients empty their bladder immediately before scan acquisition.
Image acquisition — Patient lies supine on the scanner bed. Scan duration is typically 25-40 minutes depending on patient size and field of view (typically vertex to mid-thigh). Patient must remain still during acquisition; gentle breathing is fine.
Post-scan — Cannula removal; standard discharge advice (hydrate well for 24 hours to encourage tracer clearance through urine); no special radiation precautions for most patients.

What the Krenning score means

The Krenning score is a semi-quantitative grading of tumour uptake on somatostatin receptor imaging, originally developed for OctreoScan and now extensively used for DOTATATE PET-CT^[6]:

Krenning score	Interpretation	PRRT implication
0	No uptake (no SSTR expression)	PRRT not appropriate
1	Faint uptake, less than normal liver	PRRT generally not appropriate
2	Moderate uptake, equal to normal liver	PRRT candidate (lower bound)
3	Intense uptake, higher than normal liver but lower than spleen	PRRT candidate (typical)
4	Very intense uptake, higher than spleen	Strong PRRT candidate

The standard threshold for PRRT eligibility is Krenning score ≥ 2 in target lesions, with the additional requirement that there are no large measurable lesions showing Krenning 0-1 (i.e., disease heterogeneity matters — if many lesions are SSTR-negative on imaging, PRRT may not control the overall disease burden)^[7].

How the radiologist reads the scan

A standard DOTATATE PET-CT report typically describes^[8]:

Tracer biodistribution — physiological uptake in pituitary, salivary glands, thyroid, spleen (typically the most intense normal uptake), adrenals, liver background, pancreas (uncinate process), kidneys, urinary bladder.
Primary tumour — if known and visible, with maximum standardised uptake value (SUVmax) and Krenning score.
Metastatic disease — listed by site (liver, lymph nodes, bone, lung, peritoneal, other), with SUVmax and Krenning score for representative lesions.
Lesion heterogeneity — note if any lesions show low or absent uptake while others are intensely positive (this matters for PRRT planning).
Comparison with prior imaging — if available, comparison with previous DOTATATE PET-CT or cross-sectional imaging.
Incidental findings — any non-NET findings on the CT component (e.g., thyroid nodules, kidney cysts) that require follow-up.
Conclusion — summary of disease burden, dominant Krenning score, and treatment-relevant findings.

Limitations and complementary imaging — FDG PET-CT

DOTATATE PET-CT visualises SSTR expression, not metabolic activity. For some NET patients — particularly those with higher-grade disease (Ki-67 >20%) or aggressive biology — FDG PET-CT (which visualises glucose metabolism) provides complementary information^[9]:

SSTR-positive, FDG-negative — typical well-differentiated NET; favourable for PRRT and somatostatin analogue therapy.
SSTR-positive, FDG-positive — heterogeneous biology; PRRT still typically appropriate but with closer monitoring and consideration of combination strategies.
SSTR-negative, FDG-positive — poorly-differentiated or dedifferentiated disease; PRRT not appropriate; consider chemotherapy.
SSTR-negative, FDG-negative — uncommon; raises questions about diagnosis or indolent biology.

The combined SSTR-PET + FDG-PET evaluation (sometimes called dual tracer imaging) is increasingly standard for higher-grade NETs and for patients facing complex treatment decisions^[10].

The bottom line

Ga-68 DOTATATE PET-CT visualises somatostatin receptor type 2 (SSTR2) expression and is the molecular imaging foundation of contemporary NET management — particularly for staging, response assessment, and PRRT eligibility^[1].
Patient preparation is simple: stop long-acting somatostatin analogue therapy approximately 4 weeks before the scan (current EANM guidance); no fasting required; bring prior imaging and pathology reports^[4].
The scan visit takes approximately 2-3 hours total: cannulation, tracer injection, 60-minute uptake period, 25-40 minute scan acquisition.
The Krenning score (0-4) grades tumour uptake relative to normal liver and spleen. PRRT eligibility typically requires Krenning ≥ 2 in target lesions^[6].
For higher-grade NETs (Ki-67 >20%) or aggressive biology, complementary FDG PET-CT provides additional information about tumour heterogeneity and treatment strategy^[9].

Important

This article describes Ga-68 DOTATATE PET-CT in general terms. Specific scan protocols, preparation instructions, and report interpretation are determined by your treating team based on your individual clinical context. Always follow the specific instructions provided by your imaging centre.

"Patients sometimes arrive at our clinic having been told they are not a PRRT candidate, when in fact they have not yet had a proper Ga-68 DOTATATE PET-CT — or they had one many years ago without dose-fractionated long-acting somatostatin analogue timing. The single most important test before any PRRT conversation is current DOTATATE imaging with a calculated Krenning score for representative lesions. Without it, the question simply cannot be answered. With it, the answer is usually surprisingly clear."

Dr. Ishita B. Sen, MD · Director & Chief, Nuclear Medicine, FMRI

Ga-68 DOTATATE PET-CT scheduling · NET imaging at FMRI

For Ga-68 DOTATATE PET-CT scheduling at FMRI Gurugram — for initial NET staging, PRRT eligibility confirmation, response assessment, or restaging at progression — our nuclear medicine team can coordinate timing around somatostatin analogue therapy and provide same-week scheduling for most indications.

Schedule DOTATATE PET-CT · WhatsApp +91 8800 988936

For patients & referring clinicians

Frequently asked questions

Q01 Is Ga-68 DOTATATE PET-CT safe?

Ga-68 DOTATATE PET-CT is a low-radiation-dose imaging study with an excellent safety profile. The typical effective dose is approximately 4-5 mSv from the Ga-68 DOTATATE component plus the CT contribution (variable, typically 5-15 mSv depending on CT protocol). This is comparable to one to two CT abdomen/pelvis studies and is well below thresholds associated with measurable harm. Allergic reactions to the tracer are extremely rare [1].

Q02 How long does the scan take?

The scan visit takes approximately 2-3 hours total. This includes check-in and consent (15-30 min), cannulation and tracer injection (15 min), a 60-minute uptake period during which patients rest comfortably, scan acquisition itself (25-40 min depending on patient size and field of view), and post-scan discharge. The actual time lying on the scanner is approximately 25-40 minutes [5].

Q03 Do I need to stop my octreotide LAR before the scan?

Yes — current EANM (European Association of Nuclear Medicine) guidance recommends that long-acting somatostatin analogue therapy (octreotide LAR or lanreotide) be timed so the DOTATATE PET-CT is performed at least 4 weeks after the last injection. The rationale: the long-acting analogue occupies SSTR2 receptors and can reduce tracer binding to tumour, producing falsely low Krenning scores [4]. Short-acting octreotide should be stopped at least 24 hours before scanning. Your treating team will coordinate timing.

Q04 What is the Krenning score?

The Krenning score is a 5-point semi-quantitative grading of tumour uptake on somatostatin receptor imaging: 0 (no uptake), 1 (faint, less than liver), 2 (moderate, equal to liver), 3 (intense, higher than liver but lower than spleen), 4 (very intense, higher than spleen). For PRRT eligibility, the standard threshold is Krenning ≥ 2 in target lesions, with consideration of disease heterogeneity (whether some lesions show low or absent uptake) [6][7].

Q05 What does a high Krenning score mean for treatment?

A higher Krenning score (3 or 4) indicates strong SSTR2 expression in tumour and is associated with better response to PRRT in published cohorts. The relationship between Krenning score and PRRT response is well-documented but not absolute — other factors (tumour burden, Ki-67, prior treatment, organ function) also influence response. A Krenning 4 patient is a strong PRRT candidate but cannot be guaranteed a response; a Krenning 2 patient is a valid candidate but with somewhat lower expected response [7].

Q06 Do I need fasting before the scan?

No — fasting is not required for Ga-68 DOTATATE PET-CT (unlike FDG PET-CT which requires 6-hour fasting). You can eat and drink normally before the scan. Adequate hydration with water is encouraged. Empty your bladder immediately before the scan acquisition [4].

Q07 Why do I sometimes need an FDG PET-CT as well?

For higher-grade NETs (Ki-67 >20%) or aggressive disease, FDG PET-CT provides complementary information about glucose metabolism. The combination — DOTATATE PET-CT visualising SSTR expression plus FDG PET-CT visualising metabolic activity — gives a more complete picture of tumour heterogeneity. SSTR-positive/FDG-negative typically favours PRRT; SSTR-negative/FDG-positive favours chemotherapy; mixed patterns require nuanced multidisciplinary discussion [9][10].

Q08 Can I have a DOTATATE PET-CT if I am pregnant?

Pregnancy is generally a contraindication for elective DOTATATE PET-CT because of the radiation dose to the fetus. If imaging is essential during pregnancy, alternative non-ionising imaging (MRI) is preferred. Breastfeeding patients may need to interrupt breastfeeding for 24-48 hours after tracer injection. Always inform the imaging team if you are or might be pregnant or are breastfeeding [4].

Q09 What happens after I receive the tracer? Am I radioactive?

After the tracer injection, you will emit a small amount of radiation for several hours as the tracer decays (Ga-68 has a physical half-life of 68 minutes). Standard post-scan advice: drink plenty of water for 24 hours to encourage tracer clearance through urine; flush the toilet twice after voiding for the first 12 hours. No special restrictions on close contact with family, including children and pregnant women, are typically required for most adult patients. Your centre will provide specific written guidance [5].

Q10 How soon will I get the report?

Most centres provide a preliminary report within 24-48 hours and a final report within 2-5 working days. Time-sensitive cases (acute hospitalised patients, urgent treatment decisions) typically receive same-day or next-day reporting. Discuss timing with your imaging centre at the time of scheduling.

Q11 Can DOTATATE PET-CT distinguish between cancer and benign tissue?

DOTATATE PET-CT visualises SSTR2 expression, which is present on most well-differentiated NETs but also on some benign tissues (pituitary, spleen, adrenals are normal physiological uptake sites; inflammatory and reactive lymph nodes can show variable uptake). The radiologist interprets the pattern of uptake in context with anatomical findings on the CT component, prior imaging, and clinical information. The scan is highly specific for NET in most contexts but is not a substitute for biopsy when diagnosis is unclear [8].

Q12 Where can I have a DOTATATE PET-CT in India?

Ga-68 DOTATATE PET-CT is available at most tertiary nuclear medicine centres in India, including FMRI Gurugram, AIIMS New Delhi, Tata Memorial Hospital, Apollo Hospitals, and many others. Centre selection should consider: in-house Ga-68 generator availability (versus reliance on weekly tracer supply), experience with NET imaging, integrated multidisciplinary review, and turnaround time for the report. For NET imaging at FMRI, WhatsApp +91 8800 988936 to schedule.

Citations & references

All clinical numbers above are sourced from the primary literature listed below. Every reference links to the open journal page or the FDA archive — open in a new tab to verify.

[1] Bozkurt MF, Virgolini I, Balogova S, et al. Guideline for PET/CT imaging of neuroendocrine neoplasms with ⁶⁸Ga-DOTA-conjugated somatostatin receptor targeting peptides. Eur J Nucl Med Mol Imaging. 2017;44(9):1588-1601. View source ↗

[2] Sadowski SM, Neychev V, Millo C, et al. Prospective study of ⁶⁸Ga-DOTATATE positron emission tomography/computed tomography for detecting GEP-NETs and unknown primary sites. J Clin Oncol. 2016;34(6):588-596. View source ↗

[3] Hope TA, Bergsland EK, Bozkurt MF, et al. Appropriate Use Criteria for Somatostatin Receptor PET Imaging in Neuroendocrine Tumors. J Nucl Med. 2018;59(1):66-74. View source ↗

[4] Bozkurt MF, Virgolini I, Balogova S, et al. EANM procedure guidelines for somatostatin receptor imaging with ⁶⁸Ga-DOTA-conjugated peptides. Eur J Nucl Med Mol Imaging. 2017;44(9):1588-1601. View source ↗

[5] Sundin A, Arnold R, Baudin E, et al. ENETS Consensus Guidelines for the Standards of Care in NEN: Radiological, Nuclear Medicine and Hybrid Imaging. Neuroendocrinology. 2017;105(3):212-244. View source ↗

[6] Krenning EP, Valkema R, Kooij PP, et al. Scintigraphy and radionuclide therapy with [indium-111-labelled-diethyl triamine penta-acetic acid-D-Phe1]-octreotide. Ital J Gastroenterol Hepatol. 1999;31 Suppl 2:S219-S223. View source ↗

[7] Hicks RJ, Kwekkeboom DJ, Krenning E, et al. ENETS Consensus Guidelines for the Standards of Care in Neuroendocrine Neoplasms: PRRT. Neuroendocrinology. 2017;105(3):295-309. View source ↗

[8] Hofman MS, Lau WF, Hicks RJ. Somatostatin receptor imaging with ⁶⁸Ga DOTATATE PET/CT: clinical utility, normal patterns, pearls, and pitfalls in interpretation. RadioGraphics. 2015;35(2):500-516. View source ↗

[9] Chan DL, Pavlakis N, Schembri GP, et al. Dual Somatostatin Receptor/FDG PET/CT Imaging in Metastatic Neuroendocrine Tumours. Theranostics. 2017;7(5):1149-1158. View source ↗

[10] Binderup T, Knigge U, Loft A, et al. ¹⁸F-fluorodeoxyglucose positron emission tomography predicts survival of patients with neuroendocrine tumors. Clin Cancer Res. 2010;16(3):978-985. View source ↗

[11] Strosberg J, El-Haddad G, Wolin E, et al. Phase 3 Trial of ¹⁷⁷Lu-Dotatate for Midgut NETs (NETTER-1). N Engl J Med. 2017;376(2):125-135. View source ↗

[12] Singh S, Halperin D, Myrehaug S, et al. [¹⁷⁷Lu]Lu-DOTA-TATE plus long-acting octreotide versus high-dose long-acting octreotide for newly diagnosed, advanced grade 2-3 GEP-NETs (NETTER-2). Lancet. 2024;403(10446):2807-2817. View source ↗

[13] Falconi M, Eriksson B, Kaltsas G, et al. ENETS Consensus Guidelines for Pancreatic NETs. Neuroendocrinology. 2016;103(2):153-171. View source ↗

[14] Caplin ME, Baudin E, Ferolla P, et al. Pulmonary neuroendocrine (carcinoid) tumors: ENETS expert consensus. Ann Oncol. 2015;26(8):1604-1620. View source ↗

[15] Pavel M, Öberg K, Falconi M, et al. ESMO Clinical Practice Guidelines for GEP-NEN. Ann Oncol. 2020;31(7):844-860. View source ↗

[16] Brabander T, van der Zwan WA, Teunissen JJM, et al. Long-Term Efficacy, Survival, and Safety of [¹⁷⁷Lu-DOTA⁰,Tyr³]octreotate. Clin Cancer Res. 2017;23(16):4617-4624. View source ↗

[17] Vyakaranam AR, Crona J, Norlén O, et al. Favorable outcome in PPGL treated with ¹⁷⁷Lu-DOTATATE. Cancers (Basel). 2019;11(7):909. View source ↗

[18] Brunner P, Jörg AC, Glatz K, et al. The prognostic and predictive value of SSTR2 immunohistochemistry in patients with metastatic neuroendocrine neoplasms. Eur J Nucl Med Mol Imaging. 2017;44(3):468-475. View source ↗

[19] Werner RA, Bluemel C, Allen-Auerbach MS, et al. ⁶⁸Gallium- and ⁹⁰Yttrium-/¹⁷⁷Lutetium: "theranostic twins" for diagnosis and treatment of NETs. Ann Nucl Med. 2015;29(1):1-7. View source ↗

[20] Carlsen EA, Fazio N, Granberg D, et al. PRRT in metastatic neuroendocrine carcinoma. Endocr Relat Cancer. 2019;26(2):227-239. View source ↗

[21] Geijer H, Breimer LH. Somatostatin receptor PET/CT in neuroendocrine tumours: update on systematic review and meta-analysis. Eur J Nucl Med Mol Imaging. 2013;40(11):1770-1780. View source ↗

[22] Yang J, Kan Y, Ge BH, et al. Diagnostic role of Gallium-68 DOTATOC and Gallium-68 DOTATATE PET in patients with neuroendocrine tumors: meta-analysis. Acta Radiol. 2014;55(4):389-398. View source ↗

[23] Treglia G, Castaldi P, Rindi G, et al. Diagnostic performance of Gallium-68 somatostatin receptor PET and PET/CT in patients with thoracic and gastroenteropancreatic neuroendocrine tumours: meta-analysis. Endocrine. 2012;42(1):80-87. View source ↗

[24] Hofman MS, Hicks RJ. How We Read Oncologic FDG PET/CT. Cancer Imaging. 2016;16(1):35. View source ↗

[25] Wild D, Bomanji JB, Benkert P, et al. Comparison of ⁶⁸Ga-DOTANOC and ⁶⁸Ga-DOTATATE PET/CT within patients with gastroenteropancreatic neuroendocrine tumors. J Nucl Med. 2013;54(3):364-372. View source ↗

[26] Mittal BR, Kashyap R, Bhattacharya A, et al. ¹⁷⁷Lu-DOTATATE Therapy in Indian Patients with Metastatic NETs. Indian J Nucl Med. 2017;32(4):309-315. View source ↗

[27] Strosberg JR, Halfdanarson TR, Bellizzi AM, et al. NANETS Consensus Guidelines for Surveillance and Medical Management of Midgut NETs. Pancreas. 2017;46(6):707-714. View source ↗

[28] Halfdanarson TR, Strosberg JR, Tang L, et al. NANETS 2020 Consensus on Pancreatic NETs. Pancreas. 2020;49(7):863-881. View source ↗

[29] Hennrich U, Kopka K. Lutathera®: The First FDA- and EMA-Approved Radiopharmaceutical for PRRT. Pharmaceuticals (Basel). 2019;12(3):114. View source ↗

[30] Sansovini M, Severi S, Ianniello A, et al. Long-term follow-up and role of FDG PET in advanced pancreatic neuroendocrine patients treated with ¹⁷⁷Lu-DOTATATE. Eur J Nucl Med Mol Imaging. 2017;44(3):490-499. View source ↗

[31] Reubi JC, Schar JC, Waser B, et al. Affinity profiles for human somatostatin receptor subtypes SST1-SST5 of somatostatin radiotracers selected for scintigraphic and radiotherapeutic use. Eur J Nucl Med. 2000;27(3):273-282. View source ↗

About the Author

Dr. Ishita B. Sen

MBBS · MD (Nuclear Medicine) · DNB · Post-doctoral Fellowship, Memorial Sloan Kettering Cancer Center, New York

Director and Chief of Nuclear Medicine at Fortis Memorial Research Institute. Co-founder of Theranostic Physicians Private Limited (TPPL). Two decades of clinical practice in PSMA imaging and PSMA-directed radioligand therapy, with one of the largest Indian institutional experiences in Lu-PSMA.

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