Preoperative planar lymphoscintigraphy allows for sentinel lymph node detection in 51 dogs improving staging accuracy: Feasibility and pitfalls

Sentinel lymph node (SLN) mapping is the current gold standard for the oncological staging of solid malignancies in humans. This prospective observational study describes the feasibility and the limits of preoperative lymphoscintigraphy for SLN detection in dogs with spontaneous malignancies and the improvements in staging accuracy. Client‐owned dogs with confirmed malignant neoplasia and absence of distant metastasis were prospectively enrolled. Lymphoscintigraphy was performed after the peritumoral injection of Technetium‐99m labeled nanocolloids. Regional dynamic and static images were acquired, with and without masking of the injection site with a lead shield. The dogs were then subjected to surgery for tumor excision and SLN extirpation. Intraoperative SLN detection was performed by combining methylene blue dye and a dedicated gamma probe. Overall, 51 dogs with a total of 60 solid malignant tumors were enrolled. Lymphoscintigraphy identified at least one SLN in 57 of 60 cases (95%). The SLN did not always correspond to the regional lymph node (35/57, 61.4%). The use of a lead shield, masking the injection site, markedly improved the SLN visibility. The median time of SLN appearance was 11.4 ± 9.3 min. No side effects were observed. Preoperative lymphoscintigraphy allows for SLN detection in dogs and can improve staging accuracy by either identifying the SLN in a different lymphosome than clinically expected or discriminating the draining node in uncertain cases. The combined use of preoperative and intraoperative techniques is recommended to increase the SLN detection rate.

Radiomics of cholangiocarcinoma on pretreatment CT can identify patients who would best respond to radioembolisation

OBJECTIVES

Results after trans-arterial radioembolisation (TARE) for intrahepatic cholangiocarcinoma (iCC) depend on the architecture of the tumour. This latter can be quantified through computed tomography (CT) texture analysis. The aims of the present study were to analyse relationships between CT textural features prior to TARE and objective response (OR), progression-free survival (PFS), and overall survival (OS).

METHODS

Texture analysis was retrospectively applied to 55 pre-TARE CT scans of iCCs, focusing attention on the histogram-based features and the grey-level co-occurrence matrix (GLCM). Texture features were harmonised using the ComBat procedure. Objective response was assessed using the Response Evaluation Criteria In Solid Tumours 1.1. The least absolute shrinkage and selection operator (LASSO) method was applied to select the most useful textural features related to OR.

RESULTS

Of the 55 patients, 53 had post-TARE imaging available, showing OR in 56.6% of cases. Texture analysis showed that iCCs showing OR after TARE had a higher uptake of iodine contrast in the arterial phase (higher mean histogram values, p < 0.001) and more homogeneous distribution (lower kurtosis, p = 0.043; GLCM contrast, p = 0.004; GLCM dissimilarity, p = 0.005, and higher GLCM homogeneity, p = 0.005; and GLCM correlation p = 0.030) at the pre-TARE CT scan. A favourable radiomic signature was calculated and observed in 15 of the 55 patients. The median PFS of these 15 patients was 12.1 months and that of the remaining 40 patients was 5.1 months (p = 0.008).

CONCLUSIONS

Texture analysis of pre-TARE CT scans can quantify vascularisation and homogeneity of iCC architecture, providing clinical information useful in identifying ideal TARE candidates.

KEY POINTS

• Hypervascular tumours with a more homogeneous uptake of iodine contrast in the arterial phase were those most likely to be effectively treated by TARE. • The arterial phase was observed to be the best acquisition phase for providing information regarding the "sensitivity" of the tumour to TARE. • Patients with favourable radiomic signature showed a median progression-free survival of 12.1 months versus 5.1 months of patients with an unfavourable signature (p = 0.008).

Androgen deprivation therapy influences the uptake of 11C-choline in patients with recurrent prostate cancer: the preliminary results of a sequential PET/CT study

PURPOSE

The influence of androgen deprivation therapy (ADT) on (11)C-choline uptake in patients with prostate cancer (PC) has not yet been clarified. The aim of our study was to investigate this issue by means of sequential (11)C-choline positron emission tomography (PET)/CT in patients with recurrent PC.

METHODS

We retrospectively studied 14 recurrent PC patients (mean age 67 years, range 55-82) during follow-up after radical prostatectomy (RP) with rising serum prostate-specific antigen (PSA) levels. All patients had undergone at least two consecutive (11)C-choline PET/CT scans: the first (11)C-choline PET/CT before commencing ADT and the second (11)C-choline PET/CT after 6 months of ADT administration.

RESULTS

The mean serum PSA level before ADT was 17.0 ± 44.1 ng/ml. After 6 months of ADT administration the PSA value significantly decreased in comparison to baseline (PSA = 2.4 ± 3.1 ng/ml, p < .025). Moreover, before starting ADT, 13 of 14 patients had positive (11)C-choline PET/CT for metastatic spread, while after 6 months of ADT administration in 9 of 14 patients (11)C-choline PET/CT became negative.

CONCLUSION

These preliminary results suggest that ADT significantly reduces (11)C-choline uptake in androgen-sensitive PC patients.

Incidence of increased 68Ga-DOTANOC uptake in the pancreatic head in a large series of extrapancreatic NET patients studied with sequential PET/CT

The aim of our retrospective study was to assess the incidence of increased uptake of (68)Ga-DOTANOC in the head of the pancreas among a large population of patients with extrapancreatic neuroendocrine tumors studied with serial (68)Ga-DOTANOC PET/CT.

METHODS

Patients who had undergone at least two (68)Ga-DOTANOC PET/CT studies over time were included. Uptake in the head of the pancreas was measured and compared with uptake in normal liver parenchyma (target-to-liver ratio). Patients were followed up for 6-24 mo.

RESULTS

We reviewed 245 studies performed on 100 patients and classified the pancreatic uptake as either diffuse or focal. Twenty-three patients (66 scans) showed diffuse uptake; 8 patients (16 scans) showed focal uptake. None of these 31 patients had negative findings on their subsequent scans, and vice versa. During follow-up, localization of neuroendocrine tumors in the pancreas was not suspected in any patient.

CONCLUSION

Focal and diffuse uptake of (68)Ga-DOTANOC in the head of the pancreas occurred, respectively, in 23% and 8% of the patients. The main finding of our study was that increased pancreatic uptake was stable over time.