How Does Imaging Perform in Diagnosing MPNs?

A recent review examined if there are other ways to diagnose certain myeloproliferative neoplasms (MPNs) other than through the use of bone marrow (BM) biopsy results.

Although they are standard diagnosing tools, BM biopsies may run the risk of sampling errors, show limited information on functional processes, and offer no clues about the liver and spleen.

While imaging may offer additional insight, these techniques not used in clinical practice, the authors of the review said. The results showed that while some techniques may hold promise in certain areas, a new diagnostic test will need to take into account reproducibility, safety, availability, and cost.

Writing in Cancer Imaging, their review focused on the value of BM, liver, and spleen imaging for diagnosis, prognostication, and response monitoring of essential thrombocythemia (ET), polycythemia vera (PV), and myelofibrosis (MF). All 3 are relatively rare diseases and are classified as MPNs; there is no cure other than allogeneic stem cell transplantation.

It isn’t known if a complete response is achieved without undergoing BM biopsies, which are invasive, the authors noted, and an alternative assessment represents an unmet need for these conditions.

The authors conducted a systematic literature search via PubMed, Embase, and the Cochrane Library, from inception through March 26, 2020.

Out of 5505 identified records, 55 publications were eligible for inclusion. They were written in English, published in a peer-reviewed journal, and contained original data on the imaging appearance of BM, spleen, or liver in adult patients. The main outcome measures were diagnostic accuracy, reliability, and prognosis.

The review found about 9 different techniques were used:

• Ultrasonography (4 studies, n = 176 MF)
• Quantitative computed tomography (qCT) (3 studies, n = 24 MF/31 PV/14 ET)
• Dual-energy X-ray absorptiometry (DXA) (4 studies, n = 33MF/31 PV/14 ET)
• Radiography (7 studies, n = 223 MF/41 PV)
• Magnetic resonance imaging (MRI) (15 studies, n = 115 MF/33 PV/27 ET)
• Scintigraphy (17 studies, n = 273MF/158PV)
• Single photon emission CT (SPECT) (1 study, n = 6 MF)
• Positron-emission tomography (PET) (6 studies, n = 60MF/6PV)
• Thermography (1 study, n = 6 MF)

The studies were mostly explorative and a few were able to describe imaging results that were in line with histopathological features; 7 studies were able to indicate diagnostic accuracy. These included splenic transient elastography to predict BM fibrosis grade in MF; dynamic contrast-enhanced MRI to differentiate patients with MF from patients with ET and healthy controls; and 18-fluorodeoxyglucose PET to detect residual disease after stem cell transplantation in MF.

The diagnostic accuracies of radiography and ^99mTc-colloid scintigraphy were derived from several other articles, and the reviewers wrote they had “substantial concerns regarding risk of bias and applicability across these studies, using the QUADAS-2 tool.”

Three studies noted a link between imaging results and prognosis; 1 of the 3 quantified the effect.

Two tests were narrowed down as the most promising:

• MRI (T1-weighted/STIR, Dixon) for the evaluation of BM fat content in MF, and possibly for estimating BM cellularity in ET/PV
• 18-fluorodeoxyglucose and 18-fluorothymidine PET/CT for evaluating BM fibrosis, with the former having good reported accuracy for the diagnosis of residual disease

Future research should aim to improve the methodology and evaluate diagnostic accuracy and prognostic implications, the authors said.

Reference

Slot S, van de Donk, NWCJ, Otten RHJ, et al. The value of bone marrow, liver, and spleen imaging in diagnosis, prognostication, and follow-up monitoring of myeloproliferative neoplasms: A systematic review. Cancer Imaging. Published online April 20, 2021. doi: 10.1186/s40644-021-00405-7