Diagnostic imaging of gastrointestinal neuroendocrine neoplasms with a focus on ultrasound

No exposure to ionising radiation

Repeatability

Transabdominal ultrasound – wide availability

EUS – primary method for pancreatic tumour assessment (EUS + CEUS, elastography)

EUS-FNA – possibility of cytological verification

EUS-RFA – possibility to treat focal lesions of the pancreas

CEUS, elastography – improved sensitivity for focal lesion assessment, evaluation of unclear lesions on CT/MRI

IOUS – possibility of intraoperative lesion assessment

IDUS – thorough assessment of intraductal lesions

Assessment dependent on the skills and experience of the examiner and the class of the device

Poorer sensitivity of the classic method

EUS, IOUS, IDUS, CEUS – access only at specialised centres, invasive procedures

High spatial resolution (min. 2–4 mm)

Thorough anatomical assessment of abdominal organs

Multiplanar imaging, 3D reconstruction

Disease staging

Assessment of intestinal focal lesions (enteroclysis, enterography, CT colonoscopy)

Aid in surgery planning

Availability, quick results, repeatability

Exposure to ionising radiation

Exposure to iodine contrast agent and the associated complications (renal failure, allergic reactions, hyperthyroidism)

Vasculature assessment dependent on the phase and dose of contrast

Difficult reassessment of both small and too large lesions in terms of volume

Difficult assessment of response to treatment if necrosis, haemorrhage or fibrosis are present with no reduction in lesion size

Difficult assessment in slowly growing lesions

High spatial resolution (min. 2–4 mm)

Best differentiation between soft tissues

Multiplanar imaging, 3D reconstruction

Disease staging

The best method for the assessment of hepatic and pancreatic focal lesions

Assessment of bile duct and pancreatic duct – MRI cholangiopancreatography

No exposure to ionising radiation

Gadolinium contrast – fewer allergic reactions, no kidney damage

Repeatability

High costs

Limited availability

Long duration of procedure

Patient cooperation required

Contraindication: metal parts in the body

Difficult reassessment of both small and too large lesions in terms of volume

Difficult assessment of response to treatment if necrosis, haemorrhage or fibrosis are present with no reduction in lesion size

Difficult assessment in slowly growing lesions

Functional examination

Full-body scan

CT imaging possible

Assessment of primary lesion location, stage of the disease

Evaluation for appropriate forms of treatment, assessment of treatment response, evaluation for PRRT

Monitoring, reassessment

1-day procedure, SPECT 4 hours after tracer administration

Exposure to ionising radiation

Low resolution, poor assessment of lesions <1 cm

High background hinders midgut NEN assessment on gastrointestinal examination

Low sensitivity in insulinoma detection

Possible interference with cold somatostatin analogues

Functional examination

Full-body scan

Multiplanar imaging, high resolution 4–6 mm, imaging together with CT

Possibility to calculate the level of uptake – standardised uptake value (SUV)

Good anatomical assessment

Assessment of primary lesion location, stage of disease, evaluation for appropriate forms of treatment, assessment of treatment response, monitoring, reassessment

Assessment for PRRT

1-day procedure, images obtained quickly, after 2 hours

Uptake in normal tissues (pituitary gland, spleen, kidneys, adrenal glands) or in inflammatory foci may be mistaken for a tumour

Possible interference with cold somatostatin analogues

Lack of complete validation

Functional examination

Full-body scan

Multiplanar imaging, high resolution 4–6 mm, imaging together with CT

Good anatomical assessment

Disease staging, assessment of treatment response, prognostic factor, monitoring

For the assessment of poorly differentiated NEN

Prognostic value in highly and medium differentiated NEN

Exposure to radiation

Poor uptake in NEN G1 and G2

Procedure available in specialised centres

Functional examination

Full-body scan

High specificity for phaeochromocytoma, paraganglioma, neuroblastomas

Assessment for treatment with ¹³¹I-MIBG

High background

Poor anatomical assessment

Interference from many pharmaceuticals

Need for preparation with organic iodine in order to block the thyroid gland before the procedure

Procedure 24–72 hours after tracer administration

Gastroscopy with histopathological examination (determination of histopathological diagnosis)

EUS (assessment of intramural invasion depth the presence of metastasis in regional lymph nodes) – lesions of 1–2 cm or multiple lesions

Abdominal CT scan – after filling the stomach with water to the full (stomach assessment) or 2-stage water drinking (assessment of the duodenum) and i.v. contrast administration / contrast-enhanced MRI – disease staging, distant metastasis detection

SRS – disease staging, distant metastasis detection

EUS – in every case with clinical diagnosis of a secreting tumour and when indications for biopsy are present

Hormonally active NEN of the pancreas – SRS (detection of lesions not revealed using anatomical imaging, search for the primary lesion and determination of the actual stage of the neoplasm; first-line method for the diagnosis of early recurrence, disease monitoring and selecting the right therapy), subsequently EUS and CT/MRI (assessment of anatomical location and the possibility to remove the primary lesion, cancer staging and treatment response monitoring)

Hormonally inactive NEN of the pancreas: CT/MRI (as above), subsequently SRS (as above)

Rapidly growing NEC and NEN of the pancreas – ¹⁸FDG PET/CT

SRS – method preferred for lesions smaller than 1 cm, search for the primary lesion

CT, MRI – search for the primary lesion, disease staging and assessment of treatment response

CT or MRI enterography/enteroclysis – determination of location

Colonoscopy with distal ileum assessment – search for the primary lesion and exclusion of concomitant cancer (colon cancer)

Video capsule endoscopy (VCE) and balloon enteroscopy or spiral enteroscopy – direct assessment of the mucous membrane; poorly available procedure

EUS – no utility for small intestinal lesion diagnosis

Colonoscopy – procedure of choice in the diagnosis of colon tumours

EUS – in rectal NEN of ≥5 mm; ultrasound miniprobes during colonoscopy – in colon tumours diagnosed as polyps/submucosal lesions

Abdominal and pelvic CT/MRI with the gastrointestinal tract filled with negative contrast – disease staging and assessment of metastases

CT colonography – it is not possible to perform complete colonoscopy in the case of lesions which fully obstruct the intestinal lumen

SRS – staging of the neoplastic process, assessment for SSA and PRRT

PET-CT following ¹⁸F-DOPA assessment – in the case of a negative SRS result assessment for antiproliferative treatment using SSA and PRRT

¹⁸FDG-PET/CT – in patients with NEC, patients with a rapidly growing NET with a negative SRI result and in patients assessed for radioisotope treatment