High Tumor Vascularity Research Articles

Isoform-specific promotion of breast cancer tumorigenicity by TBX3 involves induction of angiogenesis

TBX3 is a member of the highly conserved family of T-box transcription factors involved in embryogenesis, organogenesis and tumor progression. While the functional role of TBX3 in tumorigenesis has been widely studied, less is known about the specific functions of the different isoforms (TBX3iso1 and TBX3iso2) which differ in their DNA-binding domain. We therefore sought to investigate the functional consequence of this highly conserved splice event as it relates to TBX3-induced tumorigenesis. By utilizing a nude mouse xenograft model, we have identified differential tumorigenic potential between TBX3 isoforms, with TBX3iso1 overexpression more commonly associated with invasive carcinoma and high tumor vascularity. Transcriptional analysis of signaling pathways altered by TBX3iso1 and TBX3iso2 overexpression revealed significant differences in angiogenesis-related genes. Importantly, osteopontin (OPN), a cancer-associated secreted phosphoprotein, was significantly up-regulated with TBX3iso1 (but not TBX3iso2) overexpression. This pattern was observed across three non/weakly-tumorigenic breast cancer cell lines (21PT, 21NT, and MCF7). Up-regulation of OPN in TBX3iso1 overexpressing cells was associated with induction of hyaluronan synthase 2 (HAS2) expression and increased retention of hyaluronan in pericellular matrices. These transcriptional changes were accompanied by the ability to induce endothelial cell vascular channel formation by conditioned media in vitro, which could be inhibited through addition of an OPN neutralizing antibody. Within the TCGA breast cancer cohort, we identified an 8.1-fold higher TBX3iso1 to TBX3iso2 transcript ratio in tumors relative to control, and this ratio was positively associated with high-tumor grade and an aggressive molecular subtype. Collectively, the described changes involving TBX3iso1-dependent promotion of angiogenesis may thus serve as an adaptive mechanism within breast cancer cells, potentially explaining differences in tumor formation rates between TBX3 isoforms in vivo. This study is the first of its kind to report significant functional differences between the two TBX3 isoforms, both in vitro and in vivo.

Quantitative MRI for Assessment of Treatment Outcomes in a Rabbit VX2 Hepatic Tumor Model.

Globally, primary and secondary liver cancer is one of the most common cancer types, accounting 8.2% of deaths worldwide in 2018. One of the key strategies to improve the patient's prognosis is the early diagnosis, when liver function is still preserved. In hepatocellular carcinoma (HCC), the typical wash-in/wash-out pattern in conventional magnetic resonance imaging (MRI) reaches a sensitivity of 60% and specificity of 96-100%. However, in recent years functional MRI sequences such as hepatocellular-specific gadolinium-based dynamic-contrast enhanced MRI, diffusion-weighted imaging (DWI), and magnetic resonance spectroscopy (MRS) have been demonstrated to improve the evaluation of treatment success and thus the therapeutic decision-making and the patient's outcome. In the preclinical research setting, the VX2 liver rabbit tumor, which once originated from a virus-induced anaplastic squamous cell carcinoma, has played a longstanding role in experimental interventional oncology. Especially the high tumor vascularity allows assessing the treatment response of locoregional interventions such as radiofrequency ablation (RFA) and transcatheter arterial embolization (TACE). Functional MRI has been used to monitor the tumor growth and viability following interventional treatment. Besides promising results, a comprehensive overview of functional MRI sequences used so far in different treatment setting is lacking, thus lowering the comparability of study results. This review offers a comprehensive overview of study protocols, results, and limitations of quantitative MRI sequences applied to evaluate the treatment outcome of VX2 hepatic tumor models, thus generating a unique basis for future MRI studies and potential translation into the clinical setting. Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2019. J. Magn. Reson. Imaging 2020;52:668-685.

Increased insulin mRNA binding protein-3 expression correlates with vascular enhancement of renal cell carcinoma by intravenous contrast-CT and is associated with bone metastasis

PurposeTo: 1) assess the correlation between CT vascularity and a candidate molecular marker of RCC metastasis (insulin-like mRNA binding protein-3 (IMP3)); and 2) demonstrate the differential expression of IMP3 in high vs. low vascular tumors. Experimental designRetrospectively obtained contrast CT from 72 patients with primary RCC were used to establish threshold values for Low, Intermediate and High tumor vascularity. Paired histopathology specimens from 33 of these patients were used for immunohistochemistry (IHC) to correlate CT with IMP-3 expression. IMP-3 gene expression studies were performed on RCC and poorly vascular prostate cancer (PC) human bone metastases samples to confirm presence of IMP3 in metastatic samples from RCC. Gene expression studies were performed on RCC 786-O and PC3 cell lines to confirm the presence of high expression of IMP3 in the RCC cell line. ResultsIMP-3 expression positively correlated with CT vascular enhancement (p<0.01). IMP3 expression by IHC was strongly positive in all RCC, but weak in PC bone metastases. Real time RT-PCR demonstrated a significant 4-fold increase in imp-3 expression in RCC 786-O vs. PC3 cells in vitro (p<0.001). ConclusionQuantitation of pre-operative CT is a feasible method to phenotype primary RCC vascularity, which correlates with IMP-3 expression. In situ and cell line studies demonstrate an association between high IMP-3 expression and RCC bone metastasis. Studies aimed at defining the diagnostic potential of biomarkers for RCC bone metastasis, and functional significance of IMP-3 in RCC vascularity and tumor progression are warranted.

Abstract 4165: The gain-of-function truncated GLI1 (TGLI1) promotes glioblastoma angiogenesis by direct upregulation of VEGF-C and TEM7 expression

Abstract Glioblastoma (GBM) is the most frequent and deadliest brain malignancy in adults. GBM is associated with poor patient outcomes with less than five percent of patients surviving five years after diagnosis. High tumor vascularity is a hallmark of GBM and is associated with poor patient prognosis. Glioma-associated oncogene homolog 1 (GLI1) is a transcription factor that is the terminal effector of the Sonic Hedgehog (Shh) signaling pathway. Our laboratory discovered an alternatively spliced variant of GLI1, termed truncated GLI1 (TGLI1), which has an in-frame deletion of 123 nucleotides corresponding to 41 amino acids. We have demonstrated that: 1) TGLI1 is highly expressed in GBM cell lines, patient tumors, and primary culture from the Wake Forest University Brain Tumor Center of Excellence, but not in normal brain tissues; 2) TGLI1 is a gain-of-function GLI1 with a higher propensity than GLI1 to induce tumor cell migration and invasiveness; 3) TGLI1-expressing GBM xenografts have greater vascularity compared to those expressing GLI1. However, to date, the mechanisms underlying TGLI1-mediated angiogenesis in GBM are still not well understood. To address this knowledge gap, we compared TGLI1- with GLI1-expressing GBM xenografts for the expression profile using an angiogenesis PCR array consisting of 84 angiogenesis-associated genes. Our results showed that seven genes, including vascular endothelial growth factor-C (VEGF-C) and tumor endothelial marker 7 (TEM7), were expressed at higher levels in TGLI1-expressing tumors compared to those with GLI1. VEGF-C is a member of the VEGF family and binds VEGFR2/3 to promote angiogenesis and lymphangiogenesis. TEM7 is a transmembrane protein identified in the tumor endothelium with a currently unidentified function, but it may play a role in capillary morphogenesis. Results of the chromatin immunoprecipitation assay revealed that TGLI1, but not GLI1, directly bound the promoters of both VEGF-C and TEM7 genes. Conditioned medium from TGLI1-expressing GBM cells strongly induced tubule formation of brain microvascular endothelial cells and the induction was prevented when VEGF-C or TEM7 expression in the GBM cells were knocked down. Consistent with these results, we found that TGLI1 expression was positively correlated with VEGF-C, TEM7, and microvessel density in122 patient gliomas across all grades. The levels of VEGF-C and TEM7 in patient specimens were also correlated with microvessel density. Taken together, these findings further support an important role for TGLI1 in promoting GBM angiogenesis, identify VEGF-C and TEM7 as novel TGLI1 target genes and their involvement in TGLI1-mediated vascularity, and provide a new insight into the molecular underpinning of the excessive angiogenesis that is characteristic of GBM (T32CA079448 to RC; 7R01NS087169-02 to HWL). Citation Format: Richard L. Carpenter, Ivy Paw, Sherona Sirkisoon, Fei Xing, Denise Gibo, Kounosuke Watabe, Waldemar Debinski, Hui-Wen Lo. The gain-of-function truncated GLI1 (TGLI1) promotes glioblastoma angiogenesis by direct upregulation of VEGF-C and TEM7 expression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4165. doi:10.1158/1538-7445.AM2015-4165

Primary Tumor Vascularity, HIF-1α and VEGF expression in vulvar squamous cell carcinomas: their relationships with clinicopathological characteristics and prognostic impact

BackgroundIncreased vascularity is a crucial event in the tumor progression and has prognostic significance in various cancers. However, the ultimate role of angiogenesis in the pathogenesis and clinical outcome of vulvar carcinoma patients is still not settled.MethodsTumor vascularity using CD34 stained slides measured by Chalkley counting method as well as hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) immunoexpression was examined in 158 vulvar squamous cell carcinomas. Associations between vascular Chalkley count, HIF-1α and VEGF expression and clinicopathological factors and clinical outcome were evaluated.ResultsHigh CD34 Chalkley count was found to correlate with larger tumor diameter (P = 0.002), deep invasion (P < 0.001) and HIF-1α (P = 0.04), whereas high VEGF expression correlate significantly with poor tumor differentiation (P = 0.007). No significant association between CD34 Chalkley counts and VEGF expression and disease-specific survival was observed. High HIF-1α expression showed better disease specific survival in both univariate and multivariate analyses (P = 0.001).ConclusionsA significant association between high tumor vascularity and larger tumor size as well as deeper tumor invasion suggests an important role of angiogenesis in the growth and progression of vulvar carcinomas. HIF-1α expression in vulvar carcinomas was a statistically independent prognostic factor.

Use of the LigaSure™ vessel sealing system in neurofibroma excision to control postoperative bleeding

The resection of neurofibromas in Von Recklinghausen's disease (NF-1) is frequently complicated by potentially life-threatening intraoperative and postoperative hemorrhage, due to the high tumor vascularity and tissue friability. This report describes a novel technique for the resection of neurofibromas using the LigaSure™ (Valleylab, Tyco International Healthcare, Boulder, CO) vessel sealing system. We compared five cases of NF-1 tumor removal which used this vessel sealing system, with six cases that did not, and recorded the intraoperative and postoperative blood loss, length of hospitalization, and postoperative complications. In all cases employing the LigaSure™, the perioperative blood loss was less than 600ml (30∼570ml), and no patient developed a postoperative hematoma or other bleeding complications. In contrast, the cases not using the LigaSure™ had greater blood loss as well as a higher rate of postoperative hematomas. The LigaSure™ provides excellent hemostasis with few complications when used for neurofibroma removal.

Transarterial chemoembolization in the treatment of patients with unresectable cholangiocarcinoma: Results and prognostic factors governing treatment success

The aim of the study was to evaluate the effectiveness of transarterial chemoembolization (TACE) with four chemotherapeutic protocols in terms of local tumor control and survival of patients with unresectable cholangiocarcinoma (CCC) and to identify the prognostic factors governing treatment success. In the single-centre study, 115 patients (mean ages = 60.4 years) with unresectable CCC were repeatedly treated with TACE. In total, 819 chemoembolization sessions were performed in 4 week intervals with a mean of 7.1 (range, 3-30) sessions per patient. The chemotherapeutic used was Mitomycin C only in 20.9% of patients, Gemcitabine only in 7%, Mitomycin C with Gemcitabine in 47% and combination of Gemcitabine, Mitomycin C and Cisplatin in 25.1%. Local tumor response was evaluated by MRI according to RECIST. Survival data were calculated according to the Kaplan-Meier method. Prognostic factors for patient's survival were evaluated using log-rank-test. The local tumor controls were: partial response 8.7%, stable disease 57.4% and progressive disease 33.9% of patients. The median and mean survival times from the start of TACE were 13 and 20.8 months. Survival rate from the start of TACE was 52% after 1-year, 29% after 2-years and 10% after 3-years. Initial tumor response, high tumor vascularity and Child-Pugh class A were statistically significant factors for patient's survival. No statistically significant difference between patients treated with different chemotherapy protocols was noted. In conclusion, TACE is a palliative and safe treatment option for patients with unresectable CCC. Child Pugh class B, tumor hypovascularity and initially progressive disease were poor prognostic factors for patient survival.

Vessel destruction by tumor-targeting Salmonella typhimurium A1-R is enhanced by high tumor vascularity

Our laboratory has previously developed a tumor-targeting double-auxotrophic mutant of Salmonella typhimurium termed A1-R. The present report demonstrates that S. typhimurium A1-R destroys tumor blood vessels and this is enhanced in tumors with high vascularity. Red fluorescent protein (RFP)-expressing Lewis lung cancer cells (LLC-RFP) were transplanted subcutaneously in the ear, back skin, and footpad of nestin-driven green fluorescent protein (ND-GFP) transgenic nude mice, which selectively express GFP in nascent blood vessels. Color-coded in vivo imaging demonstrated that the LLC-RFP ear tumor had the highest cell density and the footpad tumor had the least with the ear tumor having more abundant blood vessels than that on the back or footpad. The tumor-bearing mice were treated with A1-R bacteria via tail-vein injection. Tumors in the ear were the earliest responders to bacterial therapy and hemorrhaged severely the day after A1-R administration. Tumors growing in the back were the second fastest responders to bacterial treatment and appeared necrotic 3 days after A1-R administration. Tumors growing in the footpad had the least vascularity and were the last responders to A1-R. Therefore, tumor vascularity correlated positively with tumor efficacy of A1-R. The present study suggests that bacteria efficacy on tumors involved vessel destruction which depends on the extent of vascularity of the tumor.

MR quantification of abnormal stromal enhancement in the periphery of invasive breast tumors

636 Background: In dynamic contrast-enhanced MRI (DCEMRI), properties of tissue microvasculature and overall vascularity can be quantified using kinetics of contrast enhancement. It has been shown that areas with high signal enhancement ratio (SER) were significantly correlated with high tumor vascularity, and that mean SER in nearby non-cancerous breast stroma was significantly associated with disease free survival. No universally accepted methods exist to determine the optimal extent of histologically normal breast tissue to treat. Although a relationship between normal tissue SER and recurrence has been observed, the spatial relationship of enhancement within the non-cancerous stroma with respect to proximity of the tumor has not been shown. We hypothesized that abnormalities in vasculature exist within the histologically normal breast stroma that can be detected by measuring changes in enhancement intensity. Methods: We performed a secondary analysis of pre-treatment DCEMRI data from 27 invasive breast cancer patients. An automated, user-independent program was used to segment breast tissue from all other structures. A SER threshold was set to identify invasive tumor regions, and a tumor proximity map was generated giving the 3D distance of each normal breast tissue voxel to the nearest tumor voxel. A percent enhancement (PE) map was calculated for the normal stroma using the signal intensity change between the pre-contrast and post-contrast images. The proximity and PE maps were then combined to measure breast tissue enhancement at various distances from the tumor. Results: PE levels in normal breast tissue situated within 2 cm of the tumor region were significantly higher than at all more distant regions. Pairwise comparisons with Turkey's adjusted p-values indicated that the mean PE at 0 cm-1 cm is significantly higher than all other distant levels (p = &lt; 0.0001) and the mean PE at 1 cm-2 cm is significantly higher than 5 cm-6 cm (p = 0.006). Conclusions: Here, we show that the normal-appearing breast stroma within 0 cm to 2 cm of a primary tumor exhibits higher enhancement levels than stroma located far from the tumor. These results suggest that tissue surrounding the tumor region may contain tumor-related angiogenesis. These findings could help personalize surgery and radiation techniques. No significant financial relationships to disclose.

Microvessel Density ≥60 Does Not Predict for Outcome After Radiation Treatment for Locally Advanced Head and Neck Squamous Cell Carcinoma

To assess whether microvessel density (MVD), an immunohistochemical marker for tumor vascularity, predicts for radiotherapy (RT) outcome in locally advanced HNSCC patients. A total of 459 patients, enrolled on the RTOG 90-03 trial, had biopsy specimens submitted, and a value for MVD determined, prior to definitive RT. 450 patients were analyzable for this study. Tumor microvessels were stained for factor VIII-related antigen using a standard immunoperoxidase method. The mean number of stained microvessel profiles, from three x200 fields containing the highest MVD (hot spot), was recorded as the MVD. A prospective value of >or=60 was chosen as the threshold for high MVD, tumor vascularity. The median follow-up for the analyzable patients with MVD assessment was 22.0 months and 79.1 months for all living patients. There were no differences concerning the pretreatment characteristics between those RTOG 90-03 patients with a value for MVD and those without a value for MVD. Thus, the present study cohort possessed comparable characteristics with the entire RTOG 90-03 population. MVD values ranged from 5 to 80, with a median value of 30. Only 37 of 450 (8.2%) patients possessed an MVD >or=60. There were no outcome differences for patients with MVD <60 versus >or=60 on multivariate analysis for time to local-regional failure (P = 0.89), time to distant metastasis (P = 0.80), disease-free survival (P = 0.46), and overall survival (P = 0.39). In this large, correlative study, a MVD >or=60, ie, high tumor vascularity, did not predict for outcome in locally advanced head and neck squamous cell carcinoma patients treated with radiotherapy.

Association of MYCN Amplification and 1p Deletion in Neuroblastomas with High Tumor Vascularity

The biologic behavior of neuroblastoma (NB) is extremely variable; therefore, the clinical behavior may be reliably predicted based on the analysis of a panel of prognostic parameters. High vascular density has been correlated with aggressive tumor progression in many types of cancers. The goal of this study was to correlate the tumor vascularity in NB with status of MYCN and the short arm of chromosome 1 (1p) to address the association between angiogenesis and genetic markers of prognostic significance. The study population consisted of 33 patients with histologically proven diagnosis of primary NB and no history of previous chemotherapy. Histologic quantitation of tumor angiogenesis was performed using 3 different methods: microvessel density, vascular grading, and Chalkley counting. MYCN amplification and 1p deletion were determined by using fluorescence in situ hybridization technique. The differentiation and mitosis-karyorrhexis index of tumor cells were also assessed using the Shimada System. MYCN amplification was present in 12 cases (36.3%), and 1p deletion in 16 (48.5%). Both genetic changes significantly correlated with increased tumor vascularity. In addition, tumor vascularity was significantly increased in tumors with high mitosis-karyorrhexis index or of undifferentiated histology. We conclude that angiogenesis shows close association with histologic and genetic prognosticators in NB. Our data support the validity of recent applications of antiangiogenic agents which interfere or block NB progression.

Angiogenesis in Neuroblastoma

Angiogenesis is a biological process by which new capillaries are formed from preexisting vessels. It occurs in physiological and pathological conditions, such as tumors, where a specific turning point is the transition from the avascular to the vascular phase. Tumor angiogenesis depends mainly on the release by neoplastic cells of growth factors specific for endothelial cells able to stimulate the growth of the host's blood vessels. In neuroblastoma, the most common extracranial solid tumor of infancy and childhood, angiogenesis also appears to play an important role in determining tumor phenotype. The nature of the angiogenic balance in neuroblastoma is complex, and a spectrum of angiogenesis stimulators, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2), and inhibitors, such as tissue inhibitors of matrix metalloproteinases (MMPs), have been detected in neuroblastoma tumors. Moreover, an increased production of MMP-2 and -9 has been also observed in advanced stages of tumor, favoring degradation of extracellular matrix and enhancing tumor dissemination. High tumor vascularity is correlated with widely disseminated disease, MYCN amplification, unfavorable histology, and poor outcome. In contrast, low tumor vascularity is associated with prognostically favorable features, such as a localized disease and favorable histology. It is becoming increasingly evident that agents that interfere with blood vessel formation also block tumor progression. Preclinical studies suggest that antiangiogenic strategies may be effective in the treatment of neuroblastoma. A major goal is the determination of whether inhibition of angiogenesis is a realistic way of inhibiting tumor cell dissemination and formation of metastasis in neuroblastoma.

Antiangiogenic therapy inhibits human neuroblastoma growth.

Angiogenesis plays a crucial role in the progression and metastasis of malignant solid tumors. In many types of cancer, including neuroblastoma, high tumor vascularity correlates with poor outcome. Recently, a number of angiogenic inhibitors have been identified that had antitumor activity in preclinical studies. To investigate the effect of the antiangiogenic agent TNP-470 on neuroblastoma tumor growth, we treated nude mice with TNP-470 after they were inoculated subcutaneously with 5 x 10(6) cells from the MYCN-amplified, human neuroblastoma cell line NBL-W-N. TNP-470 did not significantly affect tumor growth when it was administered to mice with large tumors (>600 mm3). However, when TNP-470 was administered in the setting of microscopic disease 12 hr following tumor cell inoculation, treated mice had a significantly improved tumor-free survival at 12 weeks (P < 0.001), and overall survival at 45 weeks (P < 0.001), compared to control animals. Our studies suggest that TNP-470 treatment may be most effective if it is administered in the setting of microscopic disease. We speculate that TNP-470 may inhibit neuroblastoma growth in children if treatment is initiated following intensive multimodality therapy, when residual disease is minimal.

Prognostic assessment of sonography and tumor volumetry in advanced cancer of the head and neck by use of Doppler ultrasonography

Objective: The objective of this trial was to examine the degree of tumor vascularity in lymph node metastases as depicted by computer-assisted color Doppler sonography and the tumor volumes associated with prognosis in carcinomas of the oropharynx and hypopharynx after primary radiochemotherapy. Patients And Methods: In a prospective trial, 25 patients with advanced squamous cell carcinomas of the oropharynx and hypopharynx (stage IV UICC 1997) were treated with radiochemotherapy. The color Doppler findings were quantified with a computer-assisted protocol that quantitatively describes color Doppler images by the relative color pixel density (CPD). As important prognostic cofactor, total tumor volume (TTV) was calculated from CT sections and related to the degree of vascularity. Results: Low CPD in neck metastases showed a correlation with better overall survival. A high-CPD group and a high-TTV group (median survival 10.1 months) were determined and were compared with all other CPD/TTV combinations (median survival 28.4 months); the difference in survival was significant ( P = 0.002). Conclusion: The results indicate that high tumor vascularity in combination with high TTV indicates a particularly bad prognosis in patients treated with primary radiochemotherapy for head and neck cancer. (Otolaryngol Head Neck Surg 2000;122:596-601.)

Prognostic assessment of sonography and tumor volumetry in advanced cancer of the head and neck by use of doppler ultrasonography.

The objective of this trial was to examine the degree of tumor vascularity in lymph node metastases as depicted by computer-assisted color Doppler sonography and the tumor volumes associated with prognosis in carcinomas of the oropharynx and hypopharynx after primary radiochemotherapy. In a prospective trial, 25 patients with advanced squamous cell carcinomas of the oropharynx and hypopharynx (stage IV UICC 1997) were treated with radiochemotherapy. The color Doppler findings were quantified with a computer-assisted protocol that quantitatively describes color Doppler images by the relative color pixel density (CPD). As important prognostic cofactor, total tumor volume (TTV) was calculated from CT sections and related to the degree of vascularity. Low CPD in neck metastases showed a correlation with better overall survival. A high-CPD group and a high-TTV group (median survival 10.1 months) were determined and were compared with all other CPD/TTV combinations (median survival 28.4 months); the difference in survival was significant (P = 0.002). The results indicate that high tumor vascularity in combination with high TTV indicates a particularly bad prognosis in patients treated with primary radiochemotherapy for head and neck cancer.

Contrast-Enhanced Magnetic Resonance Imaging to Assess Tumor Histopathology and Angiogenesis in Breast Carcinoma.

Contrast-enhanced magnetic resonance imaging (cMRI) is a potentially powerful new tool in the early diagnosis and staging of patients with breast carcinoma. Rapid contrast enhancement is suggestive of carcinoma and likely related to high tumor vascularity. We have developed a new cMRI technique that combines anatomic and kinetic information to help characterize breast carcinomas. Signal enhancement ratio (SER) patterns (which quantitate the kinetics of contrast enhancement using a three time point high-resolution method) were correlated in tumors from 32 patients with histopathology and tumor angiogenesis as measured by intratumoral microvessel density (iMVD). Early signal enhancement with rapid washout of intravenous contrast (i.e., corresponding to high SER values) correlated with high tumor vascularity. We found that TARGET MRI with SER analysis has potential as a tool for characterizing breast carcinoma in vivo. It enables anatomic visualization of tumor and appears to add biologic information as well, such as level of tumor angiogenesis.

Thallium Chloride 201Tl Combined with Single Photon Emission Computed Tomography (SPECT) in the Evaluation of Vestibular Schwannoma Growth

Thallium chloride 201Tl combined with SPECT was performed in a series of 29 patients with neuroradiological evidence of vestibular schwannoma (VS). The relative tumor uptake (U) and relative tumor concentration (C) of the radiotracer 201 Tl was determined, and the cerebellum served as a reference. The relative tracer concentration and uptake were correlated to tumor volume determined by gadolinium DTPA enhanced MR, to prediagnostic duration of symptoms, to tumor vascularity expressed by the average number of intratumoral vessels using the endothelial marker CD31, and to the proliferative activity in the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67. A positive 201Tl enhancement was detected in 17 tumors (n = 17). Tumors U and C were statistically unrelated to tumor volume (p = 0.236 and p =0.439). SPECT demonstrated all tumors >0.8 cm3 but it had its limitation as a diagnostic modality of small intracanalicular tumors, when compared with gadolinium DTPA enhanced MR. Relating U and C in all tumors (n = 29) and the prospectively registered data on the prediagnostic duration of symptoms, a statistical significance was found (p =0.012 and p =0.015). No statistically significant correlation was observed between U and C and the proliferative activity of the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67 (p = 0.063 and p = 0.086). A statistically significant correlation was noted between C and U in the operated group (n = 12) and tumor vascularity expressed by the average number of the intratumoral vessels (p = 0.003 and p = 0.014). SPECT was found to be superior to MR in determining VS growth potentials as it expresses tumor vascularity, which is essential for tumor growth. It seems that we now have an in vivo functional radiological modality capable of providing data on VS vascularity and determination of growth potential in the individual tumor. A high radioactive tracer uptake in the tumor corresponded to high tumor vascularity, indicating a high growth rate and vice versa.