Assessing Splenomegaly

Abstract

Rationale and Objectives To define systematic volumetric thresholds to identify and grade splenomegaly, and retrospectively evaluate the performance of radiologists to assess splenomegaly in computed tomography image data. Materials and Methods A clinical tool was developed to segment spleens from 172 contrast-enhanced clinical CT studies. There were 45 normal and 127 splenomegaly cases confirmed by radiological reports. Spleen volumes were compared to manual measurements using overlap/error. Volumetric thresholds for mild/massive splenomegaly were defined at 1/2.5 standard deviations above the average splenic volume of the healthy population. The thresholds were validated against consensus reports. The performance of radiologists in assessing splenomegaly was retrospectively evaluated. Results The automated segmentation of spleens was robust with volume overlap/error of 95.2/3.3%. There were no significant differences (p>0.2) between manual and automated segmentations for either normal/splenomegaly subgroups. Comparable correlations between interobserver and manual-automated measurements were found (R=0.99 for all). The average volume of normal spleens was 236.89±77.58 ml. For splenomegaly, average volume was 1004.75±644.27 ml. Volumetric thresholds of 314.47/430.84 ml were used to define mild/massive splenomegaly (+/−18.86 ml 95% CI). Radiologists disagreed in 23.25% (n=40) of the diagnosed cases. The area under the ROC curve of the volumetric criterion for splenomegaly detection was 0.96. Using the volumetric thresholds as the reference standard, the sensitivity of radiologists in detecting all/mild/massive splenomegaly was 95.0/66.6/99.0% at 78.0% specificity, respectively. Conclusion Thresholds for the identification and grading of splenomegaly from automatic volumetric spleen assessment were introduced. The volumetric thresholds match well with clinical interpretations for splenomegaly and may improve splenomegaly detection compared with splenic cephalocaudal height measurements or visual inspection commonly used in current clinical practice.

Assessing splenic enlargement on CT by unidimensional measurement changes in patients with colorectal liver metastases

“…First, an upper limit of 314.5 mL for splenic volume was defined as normal [7, 8, 11]. Second, an increase of >39% from baseline measure was determined to be associated with major complications and, therefore, clinically relevant [13].…”

“…Although the radiological studies cited above have emphasized accuracy of splenic volumetry to evaluate for splenomegaly, the existing methods are cumbersome in clinical practice [7, 8, 11, 12]. Our hypothesis is that a unidimensional change can accurately reflect a splenic volumetric change following chemotherapy.…”

“…Radiological assessment is often used to confirm splenomegaly, as 16% of clinically palpable spleens were found to be normal after radiological evaluation [6]. Computed tomography (CT) enables accurate, non-invasive estimation of splenic volume, but consensus about the definition of splenomegaly is lacking [7, 8]. One can estimate spleen size simply using craniocaudal length or maximum longitudinal dimension from cross-sectional imaging methods, however, due to normal anatomic variation of the organ's shape, a common definition of splenomegaly based on these measures is problematic [7, 9].…”

“…Computed tomography (CT) enables accurate, non-invasive estimation of splenic volume, but consensus about the definition of splenomegaly is lacking [7, 8]. One can estimate spleen size simply using craniocaudal length or maximum longitudinal dimension from cross-sectional imaging methods, however, due to normal anatomic variation of the organ's shape, a common definition of splenomegaly based on these measures is problematic [7, 9]. Splenic index, calculated by the product of anteroposterior width ( W ), transverse thickness ( T ), and craniocaudal height ( H ), may offer a better measure of splenic volume than unidimensional measurements.…”

“…More accurate but time-consuming methods, such as the summation of the cross-sectional areas taking into account the slice thickness, or use of the prolate ellipsoid formula, W × T × H × 0.52, also provide estimates of splenic volumes [1, 3, 8, 10, 11]. Both of these methods assume an upper limit of 314.5 mL for normal splenic volume [7, 8, 11, 12]. …”