Fig 1.
Positioning for indirect computed tomography lymphangiography (ICTL) procedure.
A dog with an oral tumor positioned in sternal recumbency with the rostral maxilla positioned on a 3-D printed bite block in preparation for computed tomography (CT) scan. All dogs were positioned similarly to limit compression on the ventral neck for improve cervical drainage. CT images were subsequently acquired with pre- and post-contrast images followed by additional CT image acquisition 3, 6 +/-12 minutes (min) following peritumoral contrast injection.
Table 1.
Cervical LN classification for dogs with oral tumors on post-contrast CT.
Table 2.
Criteria used to classify cervical LNs from dogs with oral tumors from ICTL images.
Table 3.
Histopathologic diagnosis of tumor types and presence or absence of LN metastasis in dogs with oral tumors.
Table 4.
Tumor size distribution in dogs with oral tumors.
Table 5.
Primary tumor location in 39 dogs with oral tumors and identified sentinel lymph nodes (SLNs) with ICTL for prediction of metastasis to the right and/or left mandibular lymph nodes (MLNs), and/or medial retropharyngeal lymph node (MLN).
Table 6.
Kappa agreement between reviewers for computed tomography (CT) and indirect computed tomography lymphangiography (ICTL) image feature scores.
Table 7.
Significance of logistic regression model and receiver operator characteristic (ROC) curve analysis for post-contrast computed tomography feature prediction of lymph node (LN) metastasis.
Fig 2.
Receiver operator characteristic (ROC) curves illustrate the diagnostic ability of CT composite scores for the prediction of cervical lymph node metastasis in dogs with oral tumors.
CT score A, consisting of lymph node (LN) size, shape and contrast pattern scores, was inferior to CT score B, which included CT Score A features with a subjective metastasis score. CT score B was significantly superior for the prediction of metastasis when all LN were categorized together (A; P = 0.0005)) and when MLN (B; P = 0.05) or MRLN (C; P = 0.03) were evaluated separately.
Fig 3.
Post-contrast computed tomography (CT) evaluation of cervical lymph nodes (LNs) in dogs with oral tumors.
Box and whisker plots demonstrate the median (center line) with the end of the boxes indicating the 25th and 75th percentiles and the whiskers indicating the adjacent values of values for post-contrast CT features for metastatic and non-metastatic LNs. Circles indicate outlier values, while pie charts are used for scores that only have two values. Features assessed for differentiation of metastatic from non-metastatic LNs include (A) LN long axis; (B) LN short axis; (C) LN shape score; (D) LN contrast pattern score; (E) Composite Score A; (F) Composite Score B.
Fig 4.
Short and long axis measurements for cervical lymph nodes (LNs) in dogs with oral tumors.
Box and whisker plots demonstrating the median (center line) with the end of the boxes indicating the 25th and 75th percentiles and the whiskers indicating the adjacent values of post-contrast CT values for short and long axis measurements for metastatic and non-metastatic mandibular lymph nodes (A,B) and medial retropharyngeal lymph nodes (C,D). The circles represent outlier values.
Fig 5.
Sentinel lymph node (SLN) detection on indirect computed tomography lymphangiography (ICTL).
Representative axial CT images (Soft tissue algorithm: W: 400 HU, L: 40 HU) demonstrating A: Concordance between all reviewers in identification of the left medial mandibular lymph node (MLN) as the SLN (arrow) and B: Discordance between reviewers, in which the medial MLN was the SLN (N = 2) or both the medial and lateral MLN (arrows) were identified as the SLNs (N = 1).
Fig 6.
Differences identified between composite indirect computed tomography lymphangiography (ICTL) scores between metastatic and non-metastatic cervical lymph nodes (LNs) in dogs with oral tumors.
Box and whisker plots demonstrating the median (center line) with the end of the boxes indicating the 25th and 75th percentiles and the whiskers indicating the adjacent values of differences in the composite ICTL score in non-metastatic LNs and metastatic LNs for all LNs combined (A) mandibular LNs (MLNs) alone (C), and medial retropharyngeal LNs (MRLNs) alone (E). The associated receiver operating characteristic curves demonstrate the predictive ability of the logistic regression model of the composite score for the detection of histopathologic metastasis for all LNs (B), MLNs alone (D), and the MRLNs alone (E).
Table 8.
Significance of logistic regression model and receiver operator characteristic curve analysis for imaging features of the ICTL to predict lymph node (LN) metastasis in 69 identified sentinel lymph nodes in 38 dogsa.