Research Article: Is there a reliable size cut-off for splenic involvement in lymphoma? A [18F]FDG-PET controlled study

Date Published: March 8, 2019

Publisher: Public Library of Science

Author(s): Dominik Berzaczy, Alexander R. Haug, Markus Raderer, Barbara Kiesewetter, Gundula Berzaczy, Michael Weber, Marius E. Mayerhoefer, Giorgio Treglia.


Aim of present study was to determine whether the currently recommended 13-cm cranio-caudal diameter cut-off on CT for assessment of splenic involvement in lymphoma offers adequate sensitivity and specificity.

Patients with histologically proven lymphoma who had undergone [18F]FDG-PET/CT before therapy were included. Cranio-caudal diameters of the spleen were measured on the CT component of PET/CT, and ROC analyses with calculation of respective areas under the curve (AUC) were used to determine cut-off values of cranio-caudal measurements with their respective sensitivities and specificities, using [18F]FDG-PET as the reference standard.

In 93 patients, we found a sensitivity of 74.1% and a specificity of 47% for the 13-cm splenic diameter cut-off.

Our results show reasonable, though far from perfect sensitivities and specificities for the currently recommend 13-cm splenic diameter cut-off.

Partial Text

In lymphoma patients, diagnostic imaging using the modified Ann Arbor classification still represents the backbone of disease burden assessment. Cross-sectional imaging techniques—in particular, computed tomography (CT) and positron emission tomography (PET)–play a central role within the Ann Arbor system [1]. The majority of histological lymphoma subtypes show a high glucose metabolism, and hence, 2-F-18-fluoro-2-deoxy-D-glucose ([18F]FDG)-PET, nowadays in the form of [18F]FDG-PET/CT or, less frequently, [18F]FDG-PET/MRI, is regarded as the imaging technique of choice for staging and response assessment [2]. However, access to PET/CT, and even more so, PET/MRI, is limited in comparison to CT and MRI, as hybrid scanners are typically installed at (mostly metropolitan) tertiary care centres, often with long waiting lists for these examinations. The latter factors limit access to these hybrid (i.e. metabolic and morphologic) imaging techniques, and as a consequence, CT, due to its country-wide availability and low cost, is still a very frequently used imaging test for staging and restaging of patients with lymphoma, even in those with FDG-avid subtypes that should, according to the Lugano classification [3], undergo [18F]FDG-PET/CT.

Our systematic search strategy yielded a total of 253 patients. Of those, 159 were excluded because PET tracers other than [F18]FDG were used; an imaging modality other than PET/CT was used; or pathohistology did not meet our inclusion criteria; totalling 89 patients. In addition, 16 patients were excluded for positive HIV serostatus, portal hypertension or hepatic cirrhosis and 26 patients presented with focal splenic lesions on CT. Twenty-nine double hits, using our search criteria, were removed.

Splenic involvement is frequently encountered in lymphomas, in the majority of cases together with lymph node involvement. However, isolated splenic involvement in the absence of nodal or extranodal involvement visible on CT can occur, particularly in selected histological NHL subtypes such as mantle cell lymphoma (MCL); splenic marginal zone lymphoma (SMZL) and small-cell lymphocytic lymphoma / chronic lymphocytic leukemia (SLL/CLL); hairy cell leukemia (HCL); hepatosplenic T-cell lymphoma (HSTL); lymphoplasmacytic lymphoma (LPL); T-cell large granular lymphocytic leukemia (T-LGL); and B-cell prolymphocytic leukemia (B-PLL) [7]. Notably, some of the latter subtypes, such as MZLs, SLL/CLL, and LPL, are known to show a variable FDG avidity, and as a consequence, the Lugano guidelines generally do not recommended the use of [18F]FDG-PET/CT or -PET/MRI in those subtypes, but instead, recommend CE-CT [8]. In view of the above, and because CT is often the first cross-sectional imaging test used in lymphoma patients due to the country-wide access to this technique, a reliable CT criterion for assessment of splenic involvement in lymphoma patients is desirable [9,10].




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