Targeting Peritumoral Lesions Identified by Computed Tomography and Magnetic Resonance Imaging in Feline Injection-Site Sarcomas for Microscopic Examination

Peritumoral lesions identified during in vivo imaging of feline injection-site sarcoma (FISS) are frequently interpreted as neoplastic. We recently showed that most peritumoral imaging-identified lesions (PTIILs) in FISS are non-neoplastic. In this article, we describe a protocol to target PTIIL for microscopic examination and report on the protocol's performance. Ten client-owned cats with FISS were prospectively enrolled. A fiducial marker sutured onto the skin, centered on the palpable mass, served as reference point throughout the study. Each FISS and surrounding tissue was imaged in vivo by dual phase computed tomography angiography and multiple magnetic resonance imaging pulse sequences and each PTIIL documented. Subgross measurements obtained during trimming aided localization and identification of PTIIL during microscopy. Histologic findings were categorized by descending clinical relevance: neoplastic, equivocal, non-neoplastic, within normal limits (WNL). Based on in vivo imaging resolution limits, histologic findings were ≥3 mm in at least one dimension and ≥3 mm apart. Surgical margins served as control tissue for PTIILs. Eighty-one of 87 PTIIL were examined histologically; 13 were neoplastic, 16 equivocal, and 28 non-neoplastic; 24 had no identified histologic correlate. Two neoplastic and 10 equivocal findings were located outside of PTIILs but none of them were located in sections of surgical margins. Computation of a simple confusion matrix yielded fair sensitivity (70.4%) and low specificity (59.7%) for prediction of PTIIL by histologic findings. After combining instances of normal microanatomy with non-neoplastic histologic findings, specificity increased (85.1%) and sensitivity decreased (35.8%). The protocol is a blueprint for targeting PTIIL for microscopic examination but may benefit from further refinement.

Relationships between hypoxia induced factor-1α and 18F-FDG PET/CT parameters in colorectal cancer

AIM

The hypoxia-inducible factor 1 (HIF-1) has a critical role in oxygen homeostasis and it is a transcriptional activator of angiogenesis, erythropoiesis, iron and glucose metabolism. Glucose metabolism rate is increased in some tumours via HIF-1α. Our aim is to evaluate the relationship between hypoxia in colorectal cancer, PET parameters, necrotic tissue size and pathologic prognostic factors via using HIF-1α.

MATERIALS/METHODS

70 patients (28 female/42 male; median age: 63 years) who were diagnosed with colorectal cancer via biopsy were staged with preoperative PET/CT and operated subsequently. Immunohistochemical evaluation scoring was done according to nuclear HIF-1α expression, staining density and intensity. Metabolic tumour volume (MTV), total lesion glycolysis (TLG) and tumour volume (TV) were calculated by using volume of an ellipsoid formula via CT images, and percentage of tumour necrosis (%TmNcr) that was calculated by the difference between TV and recorded MTV.

RESULTS

There was a moderately meaningful positive correlation between tumour SUVmax and TV and %TmNcr (r=0.403, p=0.001 and r=0.500, p=0.0001, respectively). There were no statistically significant relationships between HIF-1α expression levels and tumour SUVmax, TLG, MTV, TV, %TmNcr, tumour stage, lymphovascular invasion, perineural invasion and extracapsular/capsular lymph node involvement. On the other hand, strong nuclear immunohistochemical staining was seen in tumour cells adjacent to invasive border, inflammatory cells. Although not statistically significant, moderate or strong nuclear staining were seen in 64.9% of metastatic patients.

CONCLUSION

Although the presence of a positive correlation between tumour SUVmax and %TmNcr shows that there are hypoxic cells in cancer tissue with high FDG uptake, the relationship between the presence of HIF-1α and enhanced glucose metabolism and pathological prognostic factors of tumour was not shown. Strong nuclear immunohistochemical staining in tumour cells adjacent to invasive border and inflammatory cells leads us to believe that HIF-1α plays a role in the invasion area of tumour microenvironment.

Dynamic tomographic studies of interscapular feline injection-site sarcoma: essential or useless practice?

Objectives Feline injection-site sarcomas (FISSs) are soft tissue tumours typically characterised by an interscapular location and highly infiltrative behaviour. CT is considered the modality of choice for FISS staging and double positioning (dynamic approach) was reported to successfully detect the exact extent of infiltration into the muscles. The aim of the present study was to investigate the utility of the dynamic approach in feline patients referred for preoperative staging of interscapular FISS. Methods Tumour volume estimates were compared between the ellipsoid and the semi-automated segmentation methods. Two radiologists blinded to the patient coding used images from each position to assess the extent of muscular infiltration. The distance between the neoplasm and the adjacent skeletal structures (scapulae, spinous processes) was recorded in both positions by a single radiologist. Results Fifty-nine of 84 neoplasms invaded the adjacent muscular structures, with up to 15 muscles infiltrated. Between the extended and flexed position the average estimated numbers of muscles infiltrated were 1.9 (extended) and 1.84 (flexed) for observer A and 1.89 (extended) and 1.85 (flexed) for observer B. Good agreement between observers was established, with higher tumour volumes detected via the ellipsoid method. Moreover, tumours with smaller volumes showed slightly decreased muscular infiltration. Marked difference in the recorded distance between the skeletal structures and the neoplasm in the two different positions was established (mean ± SD difference spinous processes: 9.74 ± 9.57 mm; mean ± SD difference scapulae: 15.15 ± 11.76 mm). Conclusions and relevance A dynamic approach should be used for a complete evaluation of the invasiveness of FISS along with appropriate methodology for tumour volume measurement, which could potentially alter the tomographic estimation of the real dimension of the neoplasms.