CT measurement of perfusion and permeability within lymphoma masses and its ability to assess grade, activity, and chemotherapeutic response

Emerging role of quantitative imaging (radiomics) and artificial intelligence in precision oncology

Cancer is a fatal disease and the second most cause of death worldwide. Treatment of cancer is a complex process and requires a multi-modality-based approach. Cancer detection and treatment starts with screening/diagnosis and continues till the patient is alive. Screening/diagnosis of the disease is the beginning of cancer management and continued with the staging of the disease, planning and delivery of treatment, treatment monitoring, and ongoing monitoring and follow-up. Imaging plays an important role in all stages of cancer management. Conventional oncology practice considers that all patients are similar in a disease type, whereas biomarkers subgroup the patients in a disease type which leads to the development of precision oncology. The utilization of the radiomic process has facilitated the advancement of diverse imaging biomarkers that find application in precision oncology. The role of imaging biomarkers and artificial intelligence (AI) in oncology has been investigated by many researchers in the past. The existing literature is suggestive of the increasing role of imaging biomarkers and AI in oncology. However, the stability of radiomic features has also been questioned. The radiomic community has recognized that the instability of radiomic features poses a danger to the global generalization of radiomic-based prediction models. In order to establish radiomic-based imaging biomarkers in oncology, the robustness of radiomic features needs to be established on a priority basis. This is because radiomic models developed in one institution frequently perform poorly in other institutions, most likely due to radiomic feature instability. To generalize radiomic-based prediction models in oncology, a number of initiatives, including Quantitative Imaging Network (QIN), Quantitative Imaging Biomarkers Alliance (QIBA), and Image Biomarker Standardisation Initiative (IBSI), have been launched to stabilize the radiomic features.

Using Flow Characteristics in Three-Dimensional Power Doppler Ultrasound Imaging to Predict Complete Responses in Patients Undergoing Neoadjuvant Chemotherapy

OBJECTIVES

Strategies are needed for the identification of a poor response to treatment and determination of appropriate chemotherapy strategies for patients in the early stages of neoadjuvant chemotherapy for breast cancer. We hypothesize that power Doppler ultrasound imaging can provide useful information on predicting response to neoadjuvant chemotherapy.

METHODS

The solid directional flow of vessels in breast tumors was used as a marker of pathologic complete responses (pCR) in patients undergoing neoadjuvant chemotherapy. Thirty-one breast cancer patients who received neoadjuvant chemotherapy and had tumors of 2 to 5 cm were recruited. Three-dimensional power Doppler ultrasound with high-definition flow imaging technology was used to acquire the indices of tumor blood flow/volume, and the chemotherapy response prediction was established, followed by support vector machine classification.

RESULTS

The accuracy of pCR prediction before the first chemotherapy treatment was 83.87% (area under the ROC curve [AUC] = 0.6957). After the second chemotherapy treatment, the accuracy of was 87.9% (AUC = 0.756). Trend analysis showed that good and poor responders exhibited different trends in vascular flow during chemotherapy.

CONCLUSIONS

This preliminary study demonstrates the feasibility of using the vascular flow in breast tumors to predict chemotherapeutic efficacy.

Imaging for Oncologic Response Assessment in Lymphoma

OBJECTIVE

The purpose of this article is to examine the role of different imaging biomarkers, focusing in particular on the use of updated CT and PET response criteria for the assessment of oncologic treatment effectiveness in patients with lymphoma but also discussing other potential functional imaging methods and their limitations.

CONCLUSION

Lymph nodes are commonly involved by metastatic solid tumors as well as by lymphoma. Evolving changes in cancer therapy for lymphoma and metastases have led to improved clinical outcomes. Imaging is a recognized surrogate endpoint that uses established criteria based on changes in tumor bulk to monitor the effects of treatment. With the introduction of targeted therapies and novel antiangiogenic drugs, the oncologic expectations from imaging assessment are changing to move beyond simple morphologic methods. Molecular and functional imaging methods (e.g., PET, perfusion, DWI, and dual-energy CT) are therefore being investigated as imaging biomarkers of response and prognosis. The role of these advanced imaging biomarkers extends beyond measuring tumor burden and therefore might offer insight into early predictors of therapeutic response. Despite the potential benefits of these exciting imaging biomarkers, several challenges currently exist.

In Vitro and In Vivo Assessment of Nonionic Iodinated Radiographic Molecules as Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Tumor Perfusion Agents

OBJECTIVES

The aim of this study was to evaluate 4 nonionic x-ray iodinated contrast agents (CAs), commonly used in radiographic procedures, as novel chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) agents by assessing their in vitro exchange properties and preliminary in vivo use as tumor enhancing agents.

MATERIALS AND METHODS

The CEST properties, as function of pH (range, 5.5-7.9) and of radio frequency conditions (irradiation field strength range of 1-9 μT and time of 1-9 seconds), have been determined at 7 T and 310 K for 4 x-ray CAs commonly used in clinical settings, namely, iomeprol, iohexol, ioversol, and iodixanol. Their in vivo properties have been investigated upon intravenous injection in a murine HER2+ breast tumor model (n = 4 mice for each CA) using both computed tomography (CT) and MRI modalities.

RESULTS

The prototropic exchange rates measured for the 4 investigated iodinated molecules showed strong pH dependence with base catalyzed exchange rate that was faster for monomeric compounds (20-4000 Hz in the pH range of 5.5-7.9). Computed tomography quantification showed marked (up to 2 mg I/mL concentration) and prolonged accumulation (up to 30 minutes postinjection) inside tumor regions. Among the 4 agents we tested, iohexol and ioversol display good CEST contrast properties at 7 T, and in vivo results confirmed strong and prolonged contrast enhancement of the tumors, with elevated extravasation fractions (74%-91%). A strong and significant correlation was found between CT and CEST-MRI tumor-enhanced images (R = 0.70, P < 0.01).

CONCLUSIONS

The obtained results demonstrate that iohexol and ioversol, 2 commonly used radiographic compounds, can be used as MRI perfusion agents, particularly useful when serial images acquisitions are needed to complement CT information.

Lymphoma: imaging in the evaluation of residual masses

In the management of patients with lymphoma, imaging is essential not only for diagnosis but also to define prognosis and treatment by staging. Imaging is also used to assess the response to treatment that may affect the treatment strategy: new chemotherapeutic drug combinations and autologous stem cell transplantation. These different therapies have increased the need for higher accuracy to assess the response to treatment. Standardised imaging response criteria must be well known by radiologists involved in the management of patients with lymphoma. Criteria are mainly volumetric, and are obtained from CT scans. Functional imaging techniques have been shown to provide better information on the viability of residual masses than does CT assessment of size changes.

CT remains the main imaging technique to assess response to treatment based on volumetric international criteria. New functional imaging tools evaluating perfusion (CT and MRI), and particularly glucose uptake (PET), will probably play an important role in bringing additional information on the metabolism of lymphomatous masses.

Radiochemotherapy-induced changes of tumour vascularity and blood supply estimated by dynamic contrast-enhanced CT and fractal analysis in malignant head and neck tumours

OBJECTIVE

To investigate radiochemotherapy (RChT)-induced changes of transfer coefficient (K(trans)) and relative tumour blood volume (rTBV) estimated by dynamic contrast-enhanced CT (DCE-CT) and fractal analysis in head and neck tumours (HNTs).

METHODS

DCE-CT was performed in 15 patients with inoperable HNTs before RChT, and after 2 and 5 weeks. The dynamics of K(trans) and rTBV as well as lacunarity, slope of log(lacunarity) vs log(box size), and fractal dimension were compared with tumour behaviour during RChT and in the 24-month follow-up.

RESULTS

In 11 patients, an increase of K(trans) and/or rTBV after 20 Gy followed by a decrease of both parameters after 50 Gy was noted. Except for one local recurrence, no tumour residue was found during the follow-up. In three patients with partial tumour reduction during RChT, a decrease of K(trans) accompanied by an increase in rTBV between 20 and 50 Gy was detected. In one patient with continuous elevation of both parameters, tumour progressed after RChT. Pre-treatment difference in intratumoral heterogeneity with its decline under RChT for the responders vs non-responders was observed.

CONCLUSION

Initial growth of K(trans) and/or rTBV followed by further reduction of both parameters along with the decline of the slope of log(lacunarity) vs log(box size) was associated with positive radiochemotherapeutic response. Increase of K(trans) and/or rTBV under RChT indicated a poor outcome.

ADVANCES IN KNOWLEDGE

The modification of K(trans) and rTBV as measured by DCE-CT may be applied for the assessment of tumour sensitivity to chose RChT regimen and, consequently, to reveal clinical impact allowing individualization of RChT strategy in patients with HNT.

Assessment of tumor grade and angiogenesis in colorectal cancer: whole-volume perfusion CT

RATIONALE AND OBJECTIVES

The preoperative evaluation of tumor grading and angiogenesis has important clinical implications in the treatment and prognosis of patients with colorectal cancers (CRCs). The aim of the present study was to assess tumor perfusion with 256-slice computed tomography (CT) using whole-volume perfusion technology before surgery, and to investigate the differences in the perfusion parameters among tumor grades and the correlation between perfusion parameters and pathologic results in CRC.

MATERIALS AND METHODS

Thirty-seven patients with CRC confirmed by endoscopic pathology underwent whole-volume perfusion CT assessments with a 256-slice CT and surgery. Quantitative values for blood flow, blood volume, and time to peak were determined using commercial software. After surgery, resected specimens were analyzed immunohistochemically with CD105 antibodies for the quantification of microvessel density (MVD). The difference in CT perfusion parameters and MVD among different tumor differentiation grades was evaluated by the Student-Newman-Keuls test. The correlations between CT perfusion parameters and MVD were evaluated using the Pearson correlation analysis.

RESULTS

The mean blood flow was significantly different among well, moderately, and poorly differentiated groups (61.17 ± 17.97, 34.80 ± 13.06, and 22.24 ± 9.31 mL/minute/100 g, respectively; P < .05). The blood volume in the well-differentiated group was significantly higher than that in the moderately differentiated group (33.96 ± 24.81 vs. 16.93 ± 5.73 mL/100 g; P = .002) and that in the poorly differentiated group (33.96 ± 24.81 vs. 18.05 ± 6.01 mL/100 g; P = .009). The time to peak in the poorly differentiated group was significantly longer than that in the well-differentiated group (27.81 ± 11.95 vs. 17.60 ± 8.53 seconds; P = .016) and that in the moderately differentiated group (27.81 ± 11.95 vs. 18.94 ± 7.47 seconds; P = .028). There was no significant difference in the MVD among well, moderately, and poorly differentiated groups (33.47 ± 14.69, 28.89 ± 11.82, and 29.89 ± 11.02, respectively; P > .05). There was no significant correlation between CT perfusion parameters and MVD (r = 0.201, 0.295, and -0.178, respectively; P = .233, .076, and .292, respectively).

CONCLUSIONS

CT whole-volume perfusion technology has the potential to evaluate pathologic differentiation grade of CRC before surgery. However, preoperative perfusion CT parameters do not reflect the MVD of CRC.

Midtreatment evaluation of lymphoma response to chemotherapy by volume perfusion computed tomography

OBJECTIVE

The aim of this study was to search for chemotherapy-induced perfusion changes of diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma at midtreatment versus baseline volume perfusion computed tomography (VPCT).

METHODS

Forty-five consecutive patients with untreated diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma received VPCT examinations of the tumor bulk at baseline and during chemotherapy (midtreatment). Blood flow (BF), blood volume (BV), and transit constant (K-trans) were determined. Treatment response was categorized according to the Cheson criteria into complete or partial remission and stable or relapsed/progressive disease.

RESULTS

Midtreatment follow-up showed a reduction in BF, BV, and K-trans in all lymphoma subtypes compared with baseline. The reduction in BV was less pronounced in larger tumors. Notably, BF, BV, and K-trans decreased in the responders (complete remission/partial remission) when compared with the nonresponders (stable or relapsed/progressive disease). Less than 10% reduction in BF was shown to be the best VPCT criterion for the identification of nonresponse.

CONCLUSIONS

Chemotherapy-induced perfusion changes in responders are recognizable at midtreatment VPCT.

Perfusion CT of head and neck cancer

We aim to review the technique and clinical applications of perfusion CT (PCT) of head and neck cancer. The clinical value of PCT in the head and neck includes detection of head and neck squamous cell carcinoma (HNSCC) as it allows differentiation of HNSCC from normal muscles, demarcation of tumor boundaries and tumor local extension, evaluation of metastatic cervical lymph nodes as well as determination of the viable tumor portions as target for imaging-guided biopsy. PCT has been used for prediction of treatment outcome, differentiation between post-therapeutic changes and tumor recurrence as well as monitoring patient after radiotherapy and/or chemotherapy. PCT has a role in cervical lymphoma as it may help in detection of response to chemotherapy and early diagnosis of relapsing tumors.

Neoangiogenesis in prostate cancer

Prostate cancer has the second highest incidence among malignant tumors in men in Poland, and the first in the USA. Currently, medical reports state that incidentally non-diagnosed prostate cancer is present in about 30–46% of men over the age of fifty.

Tumor angiogenesis has significant implications in the diagnosis and treatment of various solid tumors. With fast, multi-slice CT scanners and their ability of qualitative and quantitative analysis of tumor angiogenesis, CT perfusion has been the subject of extensive investigation in the past twenty years.

Tumor angiogenesis is characterized morphologically by an increase in the number of blood vessels including new capillaries, capillary sprouts, non-endothelialized capillaries and arterio-venous shunts.

It is stated in the literature that pathological vessel density within prostate cancer is one of the factors determining the extent of the tumor – whether the tumor is confined to the prostate gland or extends beyond the prostate capsule. It was proved that the density of pathological vessels is higher in patients with tumors beyond the prostate capsule.

Initial publications show validity of functional imaging, such as perfusion CT in prostate cancer staging before a surgical procedure. This examination can also show excessive density of pathological vessels within the prostate gland according to increased blood volume (BV) and blood flow (BF) and pathologically increased permeability of the vessels (PS). Vessel abnormalities in the examined area are also indicated by shorter mean transit time (MTT).

Perfusion CT to assess angiogenesis in colon cancer: technical limitations and practical challenges

OBJECTIVE

Perfusion CT may have the potential to quantify the degree of angiogenesis of solid tumours in vivo. This study aims to identify the practical and technical challenges inherent to the technique, and evaluate its feasibility in colorectal tumours.

METHODS

51 patients from 2 institutions prospectively underwent a single perfusion CT on 2 different multidetector scanners. The patients were advised to breath-hold as long as possible, followed by shallow breathing, and were given intravenous buscopan to reduce movement. Numerous steps were explored to identify the challenges.

RESULTS

43 patients successfully completed the perfusion CT as per protocol. Inability to detect the tumour (n=3), misplacement of dynamic sequence co-ordinates (n=2), failure of contrast injection (n=2) and displacement of tumour (n=1) were the reasons for failure. In 14 cases excessive respiratory motion displaced the tumour out of the scanning field along the temporal sequence, leading to erroneous data capture. In nine patients, minor displacements of the tumour were corrected by repositioning the region of interest (ROI) to its original position after reviewing each dynamic sequence slice. In 20 patients the tumour was stable, and data captured from the ROI were representative, and could have been analysed by commercially available Body Tumor Perfusion 3.0® software (GE Healthcare, Waukesha, WI). Hence all data were manually analysed by MATLAB® processing software (MathWorks, Cambridge, UK).

CONCLUSION

Perfusion CT in tumours susceptible to motion during acquisition makes accurate data capture challenging and requires meticulous attention to detail. Motion correction software is essential if perfusion CT is to be used routinely in colorectal cancer.

Perfusion and flow extraction product as potential discriminators in untreated follicular and diffuse large B cell lymphomas using volume perfusion CT with attempt at histopathologic explanation

OBJECTIVE

The purpose of this article is to measure perfusion parameters, including transit constant (K(trans)), in untreated follicular and diffuse large B cell lymphoma using volume perfusion CT, to establish their discriminating role and to search for a possible histopathologic background.

SUBJECTS AND METHODS

Between January 2010 and June 2011, 46 consecutive patients with untreated histologically confirmed follicular lymphoma (n = 16) or diffuse large B cell lymphoma (n = 30) were enrolled. A 40-second volume perfusion CT of the tumor bulk using 6.9-cm z-axis coverage and a total of 26 volume measurements was performed. Blood flow (BF), blood volume (BV), and K(trans) were determined. Tumor size was recorded as the product of long- and short-axis diameters. In 13 of 46 patients, pathologic specimens of an appropriate size were available for assessment of microvessel density (MVD) and microvascular luminal diameter for comparison with volume perfusion CT measurements.

RESULTS

Mean BF, BV, and K(trans) values were significantly higher in follicular lymphoma than in diffuse large B cell lymphoma, even after controlling for patient age and tumor size (p < 0.05, respectively). Although MVD was slightly, but not significantly, higher in follicular lymphoma versus diffuse large B cell lymphoma (p > 0.05), microvascular luminal diameter was significantly larger in follicular lymphoma than in diffuse large B cell lymphoma (p < 0.05). We defined cutoff values for BF, BV, and K(trans). If the cutoff points are met for all three parameters, the overall accuracy for correctly identifying diffuse large B cell lymphoma and follicular lymphoma was 90.5% and 87.5%, respectively.

CONCLUSION

Volume perfusion CT allows assessment of differences in vascularity of follicular and diffuse large B cell lymphomas, reflecting vascular luminal variability and histopathologic anatomy.

Perfusion CT in colorectal cancer: comparison of perfusion parameters with tumor grade and microvessel density

Objective

The purpose of this study was to prospectively compare pre-operative computed tomography (CT) perfusion parameters with tumor grade from colorectal adenocarcinoma (CRC) and to correlate pre-operative CT perfusion parameters with microvessel density (MVD) to evaluate angiogenesis in CRC.

Materials and Methods

Pre-operative perfusion CTs were performed with a 64-channel multidetector row CT in 27 patients (17 women and 10 men; age range 32-82 years) who were diagnosed with CRC involving the sigmoid and rectum between August 2006 and November 2007. All patients underwent surgery without pre-operative chemotherapy or radiation therapy. Dynamic perfusion CTs were performed for 65 seconds after intravenous injection of contrast medium (100 mL, 300 mg of iodine per mL, 5 mL/sec). Before surgery, blood flow (BF), blood volume, mean transit time (MTT), and permeability-surface area product were measured in the tumor. After surgery, one gastrointestinal pathologist evaluated tumor grade and performed immunohistochemical staining using CD 34 to determine MVD in each tumor. The Kruskal-Wallis test was used to compare CT perfusion parameters with tumor grade, and Pearson's correlation analysis was used to correlate CT perfusion parameters with MVD.

Results

In 27 patients with CRC, tumor grading was as follows: well differentiated (n = 8); moderately differentiated (n = 15); and poorly differentiated (n = 4). BF was higher in moderately differentiated CRC than well differentiated and poorly differentiated CRCs (p = 0.14). MTT was shorter in moderately differentiated than well differentiated and poorly differentiated CRCs (p = 0.039). The MVD was greater in poorly differentiated than well differentiated and moderately differentiated CRCs (p = 0.034). There was no significant correlation between other perfusion parameters and tumor grade. There was no significant correlation between CT perfusion parameters and MVD.

Conclusion

BF and MTT measurement by perfusion CT is effective in predicting moderately differentiated CRCs. However, perfusion CT is limited in distinguishing well differentiated and poorly differentiated CRCs. Pre-operative perfusion CT does not reflect the MVD of CRCs.

Usefulness of perfusion CT to assess response to neoadjuvant combined chemoradiotherapy in patients with locally advanced rectal cancer

RATIONALE AND OBJECTIVES

To prospectively evaluate perfusion computed tomography (CT) for assessment of changes in tumor vascularity after chemoradiation therapy (CRT) in locally advanced rectal cancer and to analyze the correlation between baseline perfusion parameters and tumor response.

MATERIALS AND METHODS

Twenty patients with rectal cancer underwent baseline perfusion CT before CRT, and in 11 an examination after CRT was also performed. For each tumor, blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability-surface area product (PS) were quantified. The Mann-Whitney U test compared baseline perfusion parameters of responders and nonresponders and pre- and post-CRT measurements were compared by the Wilcoxon signed-rank test (P < .05 statistically significant for both tests).

RESULTS

Baseline BF was significantly lower (P = .013) and MTT was significantly higher (P = .006) in responders. Both were able to discriminate responders from nonresponders with a sensitivity of 80% and 100% and a specificity of 73.3% and 86.7%, respectively, for BF and MTT. Baseline BV and PS were not significantly different in responders and nonresponders. Perfusion parameters changed significantly in post-CRT scans compared to baseline: BF (P = .003), BV (P = .003), and PS (P = .008) decreased, whereas MTT increased (P = .006).

CONCLUSION

Baseline BF and MTT can discriminate patients with a favorable response from those that fail to respond to CRT, potentially selecting high-risk patients with resistant tumors that may benefit from an aggressive preoperative treatment approach.

Enhancement characteristics of lymphomatous lymph nodes of the mediastinum

BACKGROUND

Previous studies of CT enhancement of lymphomatous lymph nodes (LLN) of the neck showed that the LLN had lower enhancement values than normal lymph nodes.

PURPOSE

To elucidate the contrast medium enhancement curves of LLN in the mediastinum by comparing the curves of LLN with those of normal lymph nodes, and to compare the present enhancement curves of LLN of the mediastinum with the curves of LLN of the neck from a previous similar investigation.

MATERIAL AND METHODS

Twenty-four consecutive patients with LLN in the mediastinum (9 with Hodgkin's lymphoma [HL]) and 23 control patients with sarcomas and thus presumably normal mediastinal nodes underwent dynamic CT examinations. The previous, similar investigation of lymph nodes of the neck comprised 28 patients with LLN and 20 control patients.

RESULTS

The enhancement curves of the mediastinal LLN had significantly lower values than those of the mediastinal control nodes. The LLN of the mediastinum had lower mean peak contrast values than the corresponding nodes of the neck from a previous investigation.

CONCLUSION

The comparison of enhancement curves of mediastinal LLN with mediastinal control nodes showed a marked similarity with and substantiates our previous findings in lymph nodes of the neck.

Volume and attenuation computed tomography measurements for interim evaluation of Hodgkin and follicular lymphoma as an additional surrogate parameter for more confident response monitoring: a pilot study

Purpose: To retrospectively determine the potential role of additional computed tomography (CT) attenuation measurements for interim response evaluation in residual masses of patients with Hodgkin disease (HD) and follicular non-Hodgkin lymphoma (NHL). Materials and methods: In this retrospective study, 39 patients with HD and 35 patients with NHL presented with residual masses at mid-treatment CT (after 2–4 cycles of chemotherapy) and were assessed via contrast-enhanced CT at baseline, mid-treatment and post-treatment. Volume was recorded as whole-tumour volume. A tumour attenuation ratio (TAR) was calculated as the quotient of attenuation between tumour and muscle at the respective point in time versus baseline. The standard deviation of attenuation values within the tumour volume was recorded to estimate tumour heterogeneity. Results were correlated with relapse-free survival determined at a minimum of 12 months after end-treatment CT. Results: Tumour volume and TAR at interim versus baseline control were significantly reduced in responders compared with non-responders, even after controlling for age, stage, treatment regimen, and baseline tumour volume. No significant differences with respect to the standard deviation of attenuation values within the tumour volumes (tumour heterogeneity) were observed. The volume and attenuation CT (VACT) criteria yielded the highest sensitivities and specificities for the identification of non-response at a threshold of a >20% increase in volume and an increase in TAR at interim control, i.e. 88% (NHL 80%, HD 100%) and 98% (NHL 97%, HD 100%), respectively. The negative predictive values reached by VACT analysis were ≥97%, according to both parameters. Conclusion: Mid-treatment response assessment of residual masses in patients with HD and NHL using VACT may aid in the risk stratification as an additional surrogate parameter.

Neurological imaging: statistics behind the pictures

Neurological imaging represents a powerful paradigm for investigation of brain structure, physiology and function across different scales. The diverse phenotypes and significant normal and pathological brain variability demand reliable and efficient statistical methodologies to model, analyze and interpret raw neurological images and derived geometric information from these images. The validity, reproducibility and power of any statistical brain map require appropriate inference on large cohorts, significant community validation, and multidisciplinary collaborations between physicians, engineers and statisticians.

Demonstrating Intertumoural Differences in Vascular-Metabolic Phenotype with Dynamic Contrast-Enhanced CT-PET

Purpose. To assess whether the differences in vascular-metabolic relationships between lymphoma masses and colorectal liver metastases predicted from previous histopathological studies can be demonstrated by dynamic contrast-enhanced CT (DCE-CT) combined with fluorodeoxyglucose positron emission tomography (FDG-PET). Methods. DCE-CT and FDG-PET studies were drawn from an imaging archive for patients with either lymphoma masses (n = 11) or hepatic metastases from colorectal cancer (CRM: n = 12). Tumour vascularity was assessed using DCE-CT measurements of perfusion. Tumour glucose metabolism was expressed as the mean FDG Standardised Uptake Value (SUV_FDG). The relationship between metabolism and vascularity in each group was assessed from SUV_FDG /perfusion ratios and Pearson correlation coefficients. Results. An SUV_FDG threshold of 3.0 was used to designate lymphoma masses as active (AL, n = 6) or inactive lymphoma (IL, n = 5). Tumour perfusion was significantly higher in AL (0.65 mL/min/mL) than CRM (0.37 mL/min/mL: P = .031) despite similar SUV_FDG (5.05 and 5.33, resp.). AL demonstrated higher perfusion values than IL (0.24 mL/min/mL: P = .006). SUV_FDG/perfusion was significantly higher in CRM (15.3 min) than IL (4.2 min, P < .01). There was no correlation between SUV_FDG and perfusion for any patient group.

Protocol modifications for CT perfusion (CTp) examinations of abdomen-pelvic tumors: impact on radiation dose and data processing time

PURPOSE

To evaluate the effect of CT perfusion (CTp) protocol modifications on quantitative perfusion parameters, radiation dose and data processing time.

MATERIALS & METHODS

CTp datasets of 30 patients (21M:9F) with rectal (n = 24) or retroperitoneal (n = 6) tumours were studied. Standard CTp protocol included 50 sec cine-phase (0.5 sec/rotation) and delayed-phase after 70 ml contrast bolus at 5-7 ml/sec. CTp-data was sub-sampled to generate modified datasets (n = 105) with cine-phase(n = 15) alone, varying cine-phase duration (20-40 sec, n = 45) and varying temporal sampling-interval (1-3 sec, n = 45). The estimated CTp parameters (BF,BV,MTT&PS) and radiation dose of standard CTp served as reference for comparison.

RESULTS

CTp with 50 sec cine-phase showed moderate to high correlation with standard CTp for BF&MTT (r = 0.96&0.85) and low correlation for BV (0.75, p = 0.04). Limiting cine-phase duration to 30 sec demonstrated comparable results for BF&MTT, while considerable variation in CTp values existed at 20 sec. There was moderate-to-high correlation of CTp parameters with sampling interval of 1&2 sec (r = 0.83-0.97, p > 0.05), while at 3 sec only BF showed high correlation (r = 0.96, p = 0.05). Increasing sampling interval (47-60%) and reducing cine-phase duration substantially reduced dose(30.8-65%) which paralleled reduced data processing time (3-10 min).

CONCLUSION

Limiting CTp cine-phase to 30 sec results in comparable BF&MTT values and increasing cine-phase sampling interval to 2 sec provides good correlation for all CTp parameters with substantial dose reduction and improved computational efficiency.

Identification of Local Recurrence and Radiofibrosis by Computed Tomography Perfusion on Nasopharyngeal Carcinoma after Radiotherapy

Purpose

The aim of this study was to investigate the role of perfusion computed tomography (CT) for identification of local recurrence (LR) and radiofibrosis (RF) in patients with nasopharyngeal carcinoma after radiotherapy.

Methods

Forty-eight prospective patients were recruited for this study. NPC diagnosis was confirmed by pathologic biopsy examination. Immunohistochemistry staining was used on biopsy specimens, and microvessel density was calculated by microscopy. Perfusion CT was performed on both the LR group ( n = 31) and the RF group ( n = 17) after intravenous injection of contrast medium. Time-density curve, blood flow, blood volume, and mean transit time, as well as permeability surface area product, were analyzed as perfusion CT parameters. The microvessel density was compared between both the LR and RF groups.

Results

There is a significant difference between the LR and RF groups in microvessel density, the time density curve, blood flow blood volume, mean transit time, and the permeability surface area product ( P < .01).

Conclusions

The results demonstrate that perfusion CT is a reliable and accurate method to identify LR and RF after radiotherapy in patients with nasopharyngeal carcinoma.

Molecular imaging with dynamic contrast-enhanced computed tomography

Dynamic contrast-enhanced computed tomography (DCE-CT) is a quantitative technique that employs rapid sequences of CT images after bolus administration of intravenous contrast material to measure a range of physiological processes related to the microvasculature of tissues. By combining knowledge of the molecular processes underlying changes in vascular physiology with an understanding of the relationship between vascular physiology and CT contrast enhancement, DCE-CT can be redefined as a molecular imaging technique. Some DCE-CT derived parameters reflect tissue hypoxia and can, therefore, provide information about the cellular microenvironment. DCE-CT can also depict physiological processes, such as vasodilatation, that represent the physiological consequences of molecular responses to tissue hypoxia. To date the main applications have been in stroke and oncology. Unlike some other molecular imaging approaches, DCE-CT benefits from wide availability and ease of application along with the use of contrast materials and software packages that have achieved full regulatory approval. Hence, DCE-CT represents a molecular imaging technique that is applicable in clinical practice today.

Molecular and clinical aspects of targeting the VEGF pathway in tumors

Tumor angiogenesis is a complex process resulting from many signals from the tumor microenvironment. From preclinical animal models to clinical trials and practice, targeting tumors with antiangiogenic therapy remains an exciting area of study. Although many scientific advances have been achieved, leading to the development and clinical use of antiangiogenic drugs such as bevacizumab, sorafenib, and sunitinib, these therapies fall short of their anticipated benefits and leave many questions unanswered. Continued research into the complex signaling cascades that promote tumor angiogenesis may yield new targets or improve upon current therapies. In addition, the development of reliable tools to track tumor responses to antiangiogenic therapy will enable a better understanding of current therapeutic efficacy and may elucidate mechanisms to predict patient response to therapy.

Usefulness of dynamic contrast enhanced computed tomography in patients with non-small-cell lung cancer scheduled for radiation therapy

OBJECTIVE

The goal of this study was to investigate the local tumor blood supply parameters relative tumor blood volume (rTBV) and transfer coefficient (K(trans)) measurable with dynamic contrast enhanced computed tomography (DCE-CT) in patients with non-small-cell lung cancer (NSCLC) scheduled for radiation therapy (RT).

MATERIALS AND METHODS

rTBV and K(trans) were measured before RT in 31 patients with clinically inoperable NSCLC (Stages I-III), which received (n=19) or did not receive (n=12) induction chemotherapy (IChT). Possible links between rTBV and K(trans) and time-to-progression (TTP), overall survival (OS) and maximum standardized uptake value (SUV(max)) from fluorodeoxyglucose positron emission tomography as well as histology were analyzed.

RESULTS

NSCLC showed a wide range of rTBV and K(trans) values as estimated by DCE-CT (6.4±0.6ml/100ml and 18.2±1.5ml/100ml/min correspondingly). A significant difference in rTBV values in patients with IChT (4.6±0.6ml/100ml) and without IChT (7.5±0.9ml/100ml; p=0.023), depending on the number of cycles of the IChT and the clinical stage was found. A negative correlation between rTBV and TTP was revealed only in RT patients up-staged by FDG-PET/CT from stage III to stage IV (n=7, r=-0.96, p=0.0006). An inverse correlation between K(trans) and TTP (n=24, r=-0.53, p=0.008) was observed in all RT patients. No relevant correlation was detected between rTBV, K(trans) and SUV(max) or histologic subtypes and grading.

CONCLUSIONS

Tumor blood supply parameters derived from DCE-CT are useful to characterize tumor vascularization before radiotherapy in patients with NSCLC and data on outcome prediction are supplemented.

Imaging characteristics of primary laryngeal lymphoma

BACKGROUND AND PURPOSE

The larynx is a rare site for primary NHL. Fewer than 100 cases have been reported in the literature, with the largest imaging review involving only 4 patients. We describe the findings of laryngeal lymphoma on CT, PET, and MR imaging and identify features that may distinguish laryngeal lymphoma from the far more common laryngeal squamous cell carcinoma.

MATERIALS AND METHODS

Multi-institutional retrospective chart review revealed 20 patients with histopathologically proved laryngeal lymphoma. Pretreatment CT, PET, and MR images were reviewed by a head and neck radiologist, focusing on extent of tumor, cervical lymph node involvement, and enhancement patterns.

RESULTS

Patients ranged from 30 to 90 years of age with a mean of 63 years at the time of initial diagnosis and a 2:1 female predominance. The average tumor size was 37 +/- 19 mm. In all patients, laryngeal lymphoma involved the supraglottis but also extended into the glottis (65%) and hypopharynx (60%). The subglottis was less frequently involved (35%). Laryngeal cartilage invasion and cervical lymphadenopathy were each seen in 20% of patients. Lymphoma was consistently FDG-avid (100%) and usually enhanced uniformly with iodinated contrast (73%). Necrosis and calcification were not seen in any cases.

CONCLUSIONS

Although laryngeal lymphoma is rare, particular imaging features suggest this diagnosis. A large uniformly enhancing supraglottic tumor without central necrosis and without cervical lymphadenopathy is a characteristic finding of lymphoma. Similar to squamous cell carcinoma, lymphoma may extend into the subglottis, pharynx, and laryngeal cartilages.

CT perfusion in oncology: how to do it

Robust technique and accurate data analysis are required for reliable computed tomography perfusion (CTp) imaging. Multislice CT is required for high temporal resolution scanning; 16-slice (or 64-slice) scanners are preferred for adequate volume coverage. After tumour localization, the volume of CTp imaging has to be positioned to include the maximum visible area of the tumour and an adequate arterial vessel. Dynamic scans at high temporal resolution (at least 1-s gantry rotation time) are performed to visualize the first pass of contrast agent within the tumour; repeated scans with low temporal resolution can be planned for late enhancement assessment. A short bolus of conventional iodinated contrast agent, preferably with high iodine concentration, is power injected at a high flow rate (>4 ml/s) in the antecubital vein. The breath-hold technique is required for CTp imaging of the chest and upper abdomen to avoid respiratory motion; free breathing is adequate for CTp imaging of the head, neck and pelvis. Using dedicated software, a region of interest (ROI) has to be placed in an adequate artery (as arterial input) to obtain density–time curves; according to different kinetic models, colour maps of different CTp parameters are generated and generally overlaid on CT images. Additional ROIs can be positioned in the tumour, and in all other parts of the CTp volume, to obtain the values of the CTp parameters within the ROI.

Renal perfusion and hemodynamics: accurate in vivo determination at CT with a 10-fold decrease in radiation dose and HYPR noise reduction

PURPOSE

To prospectively evaluate the accuracy of computed tomographic (CT) perfusion measurements of renal hemodynamics and function obtained by using images acquired with one-tenth the typical radiation dose and postprocessed with a highly constrained back-projection (HYPR)-local reconstruction (LR) noise-reduction technique.

MATERIALS AND METHODS

This study was approved by the institutional Animal Care and Use Committee. Two consecutive CT perfusion acquisitions were performed in 10 anesthetized pigs over 180 seconds by using routine (80 kV, 160 mAs) and one-tenth (80 kV, 16 mAs) dose levels. Images obtained with each acquisition were reconstructed with identical parameters, and the one-tenth dose images were also processed with a HYPR-LR algorithm. Attenuation changes in kidneys were determined as a function of time to form time-attenuation curves (TACs). Extended gamma-variate curve-fitting was performed, and regional perfusion, glomerular filtration rate, and renal blood flow were calculated. Image quality was evaluated (in 10 pigs), and the agreement for renal perfusion and function between the routine dose and the one-tenth dose HYPR-LR images was determined (for 20 kidneys) by using statistical methods. Statistical analysis was performed by using the paired t test, linear regression, and Bland-Altman analysis.

RESULTS

TACs obtained with the one-tenth dose were similar to those obtained with the routine dose. Statistical analysis showed that there were no significant differences between the routine dose and the one-tenth dose acquisitions in renal perfusion and hemodynamic values and that there were slight but statistically significant differences in some values with the one-tenth dose HYPR-LR-processed acquisition. The image quality of the one-tenth dose acquisition was improved by using the HYPR-LR algorithm. Linear regression and Bland-Altman plots showed agreement between the images acquired by using the routine dose and those acquired by using the one-tenth dose with HYPR-LR processing.

CONCLUSION

A 10-fold dose reduction at renal perfusion CT imaging can be achieved in vivo, without loss of accuracy. The image quality of the one-tenth dose images could be improved to be near that of the routine dose images by using the HYPR-LR noise-reduction algorithm.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2531081677/-/DC1.

Perfusion-CT monitoring of cryo-ablated renal cells tumors

Background

No single and thoroughly validated imaging method in monitoring of cryoablated renal cell carcinoma (RCC) is available. The purpose of our study was to determine the feasibility of dynamic contrast-enhanced perfusion CT (pCT) in evaluating the hemodynamic response of RCC.

Methods

15 patients (14 male, 1 female; age range, 43-81 years; mean age, 62 years) with cryoablated RCC via a transperitoneal approach, underwent to pCT 6-8 months after cryo-therapy. pCT was performed for 65 seconds after intravenous injection of contrast medium (80 mL, 370 mg iodine per millilitre, 4 mL/sec). Perfusion parameters (Time/Density curve; Blood flow, BF; Blood Volume, BV; Mean Transit Time, MTT; Permeability-Surface Area Product, PS) were sampled in the cryoablated tumor area and in ipsilateral renal cortex using deconvolution-based method. A tumor was considered to be not responsive to treatment by CT evidence of pathological contrast enhancement in the cryoablated area or renal mass persistence compared with the preoperative CT control. Written informed consent was obtained from all participants before the study.

Results

After cryotherapy, successfully ablated tumor (n = 13) showed decrease in BV (5,39 +/- 1,28 mL/100 g), BF (69,92 +/- 20,12 mL/100 g/min) and PS (16,66 +/- 5,67 mL/100 g/min) value and increased value of MTT (25,35 +/- 4,3 sec) compared with those of normal renal cortex (BV: 117,86 +/- 31,87 mL/100 g/min; BF: 392,39 +/- 117,32 mL/100 g/min; MTT: 18,02 +/- 3,6 sec; PS: 81,68 +/- 22,75 mL/100 g/min). In one patient, assessment of perfusion parameters was not feasible for breathing artifacts. One tumor showed poor response to treatment by the evidence of nodular contrast enhancement in the region encompassing the original lesion. Two typical enhancement patterns were obtained comparing the Time-Density curves of responsive and not responsive ablated tumors.

Conclusion

Perfusion CT seems to be a feasible and promising technique in monitoring the effects of cryoablation therapy.

Radiation dose reduction in computed tomography: techniques and future perspective

Despite universal consensus that computed tomography (CT) overwhelmingly benefits patients when used for appropriate indications, concerns have been raised regarding the potential risk of cancer induction from CT due to the exponentially increased use of CT in medicine. Keeping radiation dose as low as reasonably achievable, consistent with the diagnostic task, remains the most important strategy for decreasing this potential risk. This article summarizes the general technical strategies that are commonly used for radiation dose management in CT. Dose-management strategies for pediatric CT, cardiac CT, dual-energy CT, CT perfusion and interventional CT are specifically discussed, and future perspectives on CT dose reduction are presented.

Body perfusion CT: technique, clinical applications, and advances

Perfusion CT has made tremendous progress since its inception and is gradually broadening its applications from the research realm into routine clinical care. This has been particularly noteworthy in the oncological setting, where perfusion CT is emerging as a valuable tool in tissue characterization, risk stratification and monitoring treatment effects especially assessing early response to novel targeted therapies. Recent technological advancements in CT have paved ways to overcome the initial limitations of restricted tissue coverage and radiation dose concerns. In this article, the authors review the basic principles and technique of perfusion CT and discuss its various oncologic and non-oncological clinical applications in body imaging.

Imaging angiogenesis

There is a need for direct imaging of effects on tumor vasculature in assessment of response to antiangiogenic drugs and vascular disrupting agents. Imaging tumor vasculature depends on differences in permeability of vasculature of tumor and normal tissue, which cause changes in penetration of contrast agents. Angiogenesis imaging may be defined in terms of measurement of tumor perfusion and direct imaging of the molecules involved in angiogenesis. In addition, assessment of tumor hypoxia will give an indication of tumor vasculature. The range of imaging techniques available for these processes includes positron emission tomography (PET), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), perfusion computed tomography (CT), and ultrasound (US).

Pancreatic endocrine tumors: tumor blood flow assessed with perfusion CT reflects angiogenesis and correlates with prognostic factors

PURPOSE

To prospectively correlate multidetector computed tomographic (CT) perfusion measurement of pancreatic endocrine tumors with tumor microvascular density (MVD) assessed by using histologic techniques and to determine whether perfusion CT parameters differ between tumor grades.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Thirty-six patients (15 men, 21 women; mean age, 53 years; range, 18-78 years) with resectable pancreatic endocrine tumors underwent presurgical dynamic perfusion CT. Twenty-eight (78%) of 36 patients were included in the study group; eight were excluded because of artifacts that were not compatible with perfusion postprocessing. Multidetector CT perfusion data were analyzed to calculate tumor and normal pancreatic blood flow, blood volume, mean transit time, and permeability-surface area product. Multidetector CT perfusion parameters were compared with intratumoral MVD by using the Spearman correlation coefficient and with World Health Organization (WHO) classification, tumor size, tumor proliferation index, hormonal profile, and presence of metastases by using Mann-Whitney tests.

RESULTS

High correlation (r = 0.620, P < .001) was observed between tumor blood flow and intratumoral MVD. Blood flow was significantly higher (P = .02) in the group of benign tumors (WHO 1) than in the groups of tumors of indeterminate prognosis (WHO 2) or well-differentiated carcinomas (WHO 3). Blood flow was significantly higher in tumors with a proliferation index of 2% or less (P = .005) and in those without histologic signs of microscopic vascular involvement (P = .008). Mean transit time was longer in tumors with lymph node (P = .02) or liver (P = .05) metastasis.

CONCLUSION

Perfusion CT is feasible in patients with pancreatic endocrine tumors and reflects MVD. Perfusion CT measurements are correlated with histoprognostic factors, such as proliferation index and WHO classification.

Imaging hemodynamics

Microvascular permeability is a pharmacologic indicator of tumor response to therapy, and it is expected that this biomarker will evolve into a clinical surrogate endpoint and be integrated into protocols for determining patient response to antiangiogenic or antivascular therapies. This review discusses the physiological context of vessel permeability in an imaging setting, how it is affected by active and passive transport mechanisms, and how it is described mathematically for both theoretical and complex dynamic microvessel membranes. Many research groups have established dynamic-enhanced imaging protocols for estimating this important parameter. This review discusses those imaging modalities, the advantages and disadvantages of each, and how they compare in terms of their ability to deliver information about therapy-associated changes in microvessel permeability in humans. Finally, this review discusses future directions and improvements needed in these areas.

Perfusion CT: noninvasive surrogate marker for stratification of pancreatic cancer response to concurrent chemo- and radiation therapy

PURPOSE

To prospectively determine whether perfusion computed tomography (CT) parameters, such as volume transfer constant (K(trans)) between blood plasma and extracellular extravascular space (EES) and blood volume calculated from dynamic CT data, can be used to predict response of pancreatic cancer to concurrent chemotherapy and radiation therapy (CCRT).

MATERIALS AND METHODS

This prospective study was institutional review board approved, and written informed consent was obtained. Thirty patients with pancreatic cancer underwent perfusion CT with 64-detector row CT before gemcitabine-based CCRT. Two perfusion parameters (K(trans) and blood volume) measured before treatment were compared between patients who responded to treatment and those who did not, as determined with World Health Organization criteria from first and second posttherapeutic follow-up CT examinations, which were performed at 3- and 6-month follow-up. Statistical analysis was performed with the two-sample t test. A receiver operating characteristic curve was used to determine the best cutoff value of perfusion parameters for differentiation of responders from nonresponders.

RESULTS

Twenty of 30 patients examined at 3-month follow-up responded to therapy. Their pretreatment K(trans) value was significantly higher than that of nonresponders (50.8 mL/100 mL/min +/- 30.5 [standard deviation] vs 19.0 mL/100 mL/min +/- 10.8, P = .001). The best cutoff value for differentiating between responders and nonresponders was 31.8 mL/100 mL/min, which yielded 75.0% sensitivity and 90.0% specificity. Ten of 18 patients examined at 6-month follow-up responded to therapy. Their pretreatment K(trans) value was significantly higher than that of nonresponders (58.6 mL/100 mL/min +/- 43.2 vs 19.8 mL/100 mL/min +/- 10.9, P = .002). Responders also had higher blood volume values, but this difference was not significant.

CONCLUSION

Tumors with a high pretreatment K(trans) value tended to respond better to CCRT than did tumors with a low pretreatment K(trans) value. Perfusion CT may be used to predict tumor response to CCRT in patients with pancreatic cancer. This might aid in development of a tailored approach to therapy in these patients.

Imaging techniques to evaluate the response to treatment in oncology: current standards and perspectives

Response evaluation in solid tumours currently uses radiological imaging techniques to measure changes under treatment. Imaging requires a well-defined anatomical lesion to be viewed and relies on the measurement of a reduction in tumour size during treatment as the basis for presumed clinical benefit. However, with the development of anti-angiogenesis agents, anatomical imaging has became inappropriate as certain tumours would not reduce in size. Functional studies are therefore necessary and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), DCE-computed tomography (CT) and DCE-ultrasonography (US) are currently being evaluated for monitoring treatments. Diffusion-weighted MR imaging (DW-MRI) and magnetic resonance spectroscopy (MRS) are also capable of detecting changes in cell density and metabolite content within tumours. In this article, we review anatomical and functional criteria currently used for monitoring therapy. We review the published data on DCE-MRI, DCE-CT, DCE-US, DW-MRI and MRS. This literature review covers the following area: basic principles of the technique, clinical studies, reproducibility and repeatability, limits and perspectives in monitoring therapy. Anatomical criteria such as response evaluation criteria in solid tumours (RECIST) will require adaptation to employ not only new tools but also different complementary techniques such as functional imaging in order to monitor therapeutic effects of conventional and new anti-cancer agents.

Imaging and cancer: a review

Multiple biomedical imaging techniques are used in all phases of cancer management. Imaging forms an essential part of cancer clinical protocols and is able to furnish morphological, structural, metabolic and functional information. Integration with other diagnostic tools such as in vitro tissue and fluids analysis assists in clinical decision-making. Hybrid imaging techniques are able to supply complementary information for improved staging and therapy planning. Image guided and targeted minimally invasive therapy has the promise to improve outcome and reduce collateral effects. Early detection of cancer through screening based on imaging is probably the major contributor to a reduction in mortality for certain cancers. Targeted imaging of receptors, gene therapy expression and cancer stem cells are research activities that will translate into clinical use in the next decade. Technological developments will increase imaging speed to match that of physiological processes. Targeted imaging and therapeutic agents will be developed in tandem through close collaboration between academia and biotechnology, information technology and pharmaceutical industries.

Hepatocellular carcinoma in cirrhotic liver disease: functional computed tomography with perfusion imaging in the assessment of tumor vascularization

RATIONALE AND OBJECTIVES

Our goal was to prospectively determine the value of perfusion computed tomography (CT) in the quantitative assessment of tumor-related angiogenesis in cirrhotic patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Forty-seven patients met all the following inclusion criteria: 1) Child-Pugh class A or B liver cirrhosis; 2) presence of a single lesion suspected as HCC at screening ultrasound examination; and 3) lesion diameter between 1 and 3 cm. All patients underwent contrast-enhanced ultrasound, pre- and post-contrast triple-phase CT, and perfusion computed tomographic study using multidetector 16-slice CT. Six parameters related to the blood microcirculation and tissue perfusion were measured for the focal liver lesion and cirrhotic parenchyma: perfusion (P), tissue blood volume (BV), hepatic perfusion index (HPI), arterial perfusion (AP), portal perfusion (PP), and time to peak (TTP). Perfusion parameters were described with quartile values of their distribution; univariate paired and unpaired Wilcoxon signed rank tests were used for statistical analysis.

RESULTS

HCC was diagnosed in 21 of the 47 patients; in the remaining 26, HCC was not found at contrast-enhanced ultrasound and multidetector 16-slice computed tomographic study. The values of perfusion parameters measured within tumor tissue were: P (ml/s/100 g): median = 47.0 (first quartile = 36.0, third quartile = 61.4); BV (ml/100 mg): median = 24.0 (first quartile = 18.7, third quartile = 29.3); HPI (%): median = 78.4 (first quartile = 62.9, third quartile = 100); AP (ml/min): median = 45.9 (first quartile = 39.0, third quartile = 60.1); PP (ml/min): median = 9.0 (first quartile = 0.0, third quartile = 24.5); and TTP (seconds): median = 18.7 (first quartile = 16.3, third quartile = 26.5). The corresponding values calculated in cirrhotic surrounding parenchyma were P (ml/s/100 g): median = 11.5 (first quartile = 9.4, third quartile = 13.9); BV (ml/100 mg): median = 10.7 (first quartile = 7.1, third quartile = 14.2); HPI (%): median = 10.6 (first quartile = 8.7, third quartile = 11.9); AP (ml/min): median = 13.2 (first quartile = 10.1, third quartile = 15.5); PP (ml/min) median = 55.2 (first quartile = 40.1, third quartile = 79.5); and TTP (seconds): median = 41.7 (first quartile = 38.9, third quartile = 44.6). P, BV, HPI, and AP values were higher (P < .001), whereas PP and TTP were lower (P < .001) in HCC relative to the surrounding liver. Values of perfusion parameters in the cirrhotic liver of patients with and without HCC were not significantly different (P > .001).

CONCLUSION

In cirrhotic patients with HCC, perfusion computed tomographic technique can provide quantitative information about tumor-related angiogenesis.

Correlation of histological findings from a large ciliochoroidal melanoma with CT perfusion and 3T MRI dynamic enhancement studies

BACKGROUND

The initial use of a 64-slice computed tomography (CT) scanner for obtaining quantitative perfusion data from a large ciliochoroidal melanoma, and correlation with 3T magnetic resonance imaging (MRI) dynamic enhancement and tumor histology.

METHODS

The CT perfusion scan was performed using 80 kVp, 250 mA and 1-sec rotation time for 40 sec. The analysis was performed using commercial perfusion analysis software with a prototype 3-dimensional motion correction tool. Dynamic contrast-enhanced 3-Tesla MRI measured the kinetics of enhancement to estimate the vascular permeability. The time-dependent enhancement patterns were obtained using the average signal intensity using Functool analysis software. The involved globe was enucleated and microscopic evaluation of the tumor was performed.

RESULTS

The perfusion parameters blood flow, blood volume and permeability surface area product in the affected eye determined by CT perfusion analysis were 118 ml/100 ml/min, 11.3 ml/100 ml and 48 ml/100 ml/min. Dynamic MRI enhancement showed maximal intensity increase of 111%. The neoplasm was a ciliochoroidal spindle cell melanoma which was mitotically active (13 mitoses/40 hpf). Vascular loops and arcades were present throughout the tumor. The patient developed metastases within 9 months of presentation.

CONCLUSION

Quantitative CT perfusion analysis of ocular tumors is feasible with motion correction software.

Accuracy of computed tomography perfusion in assessing metastatic involvement of enlarged axillary lymph nodes in patients with breast cancer

INTRODUCTION

The purpose of this study was to evaluate the diagnostic accuracy of computed tomography (CT) perfusion in differentiating metastatic from inflammatory enlarged axillary lymph nodes in patients with breast cancer.

METHODS

Twenty-five patients with 26 locally advanced breast tumors and clinically palpable axillary lymph nodes underwent dynamic multi-detector CT (LightSpeed 16; General Electric Company) at one scan per second for 150 seconds at the same table position after 40 ml intravenous contrast injection at 4.0 ml/second. Semi-automatic calculation of values of perfusion parameters - blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS) - was performed. Results were compared with pathology and with Her-2/neu and Ki-67 levels in a surgical specimen of the primary tumor.

RESULTS

Examined lymph nodes were inflammatory in 8 cases and metastatic in 18. Mean values of perfusion parameters in inflammatory and metastatic nodes, respectively, were BF of 76.18 (confidence interval [CI], 31.53) and 161.60 (CI, 40.94) ml/100 mg per minute (p < 0.05), BV of 5.81 (CI, 2.50) and 9.15 (CI, 3.02) ml/100 mg (not significant [n.s.]), MTT of 6.80 (CI, 1.55) and 5.50 (CI, 1.84) seconds (p = 0.07), and PS of 25.82 (CI, 4.62) and 25.96 (CI, 7.47) ml/100 mg per minute (n.s.). Size of nodes, stage of breast cancer, Ki-67 and Her-2/neu levels in breast cancer, and expression of primary tumor activity were not correlated to any perfusion parameter in metastatic nodes.

CONCLUSION

CT perfusion might be an effective tool for studying enlarged axillary lymph nodes in patients with breast cancer. It gives information on vascularization of lymph nodes, helping to understand the changes occurring when neoplastic cells implant in lymph nodes.

CT perfusion for the monitoring of neoadjuvant chemotherapy and radiation therapy in rectal carcinoma: initial experience

PURPOSE

To prospectively monitor changes in rectal cancer perfusion after combined neoadjuvant chemotherapy and radiation therapy with perfusion computed tomography (CT) and to evaluate whether perfusion CT findings correlate with response to therapy.

MATERIALS AND METHODS

The study was approved by the institutional ethics committee of the European Institute of Oncology; written informed consent was obtained from all participants before the study. Twenty-five patients with rectal adenocarcinoma (18 men, seven women; age range, 42-72 years; mean age, 61.3 years) underwent perfusion CT; all of them underwent neoadjuvant chemotherapy and radiation therapy, followed by surgery. In 19 patients, perfusion CT was repeated after chemotherapy and radiation therapy. Dynamic perfusion CT was performed for 50 seconds after intravenous injection of contrast medium (40 mL, 370 mg iodine per milliliter, 4 mL/sec). Blood flow (BF), blood volume (BV), mean transit time, and permeability-surface area product (PS) were computed in the tumor and in normal rectal wall by two independent blinded radiologists. Microvessel density was evaluated in pretreatment biopsy specimens in nine patients and in surgical specimens in seven patients. Wilcoxon signed-rank and rank sum tests were used for paired and independent comparisons, respectively.

RESULTS

BF, BV, and PS were significantly higher in rectal cancer than in normal rectal wall (P < .001). BF, BV, and PS significantly decreased after combined chemotherapy and radiation therapy (P < .009). No correlation was found between perfusion parameters and microvessel density, neither in baseline values nor in posttherapy changes. Baseline BF and BV in the seven patients who failed to respond to treatment were significantly lower than in the 17 responders (P = .02 for BF and < .001 for BV).

CONCLUSION

Perfusion CT has potential for monitoring the effects of combined neoadjuvant chemotherapy and radiation therapy and predicting the response of rectal cancer to such therapy.

Advanced Hepatocellular Carcinoma: CT Perfusion of Liver and Tumor Tissue—Initial Experience1

PURPOSE

To prospectively assess computed tomographic (CT) perfusion for evaluation of tumor vascularity of advanced hepatocellular carcinoma (HCC) and to correlate CT perfusion parameters with tumor grade and serum markers.

MATERIALS AND METHODS

The study was HIPAA compliant and was approved by the institutional review board. Patients provided informed consent. Thirty patients (22 men, eight women; mean age, 60 years; range, 28-79 years) with unresectable or metastatic HCC were studied. Dynamic first-pass CT perfusion was performed in primary (n=25) and metastatic (n=5) HCCs after intravenous injection of contrast medium. Data were analyzed to calculate tissue blood flow, blood volume, mean transit time, and permeability-surface area product. Repeat examination was performed in four patients within 30 hours to test reproducibility of CT perfusion. CT perfusion parameters were compared among tumors of different grades, with presence or absence of portal vein invasion, with presence or absence of cirrhosis, and of various extrahepatic metastases. Parameters were correlated with HCC serum markers. One-way analysis of variance was used to calculate variations in CT perfusion parameters.

RESULTS

Good correlation (r=0.9, P<.01) was observed between repeat examination results and first CT examination results. There was a significant difference (P <or= .05) in CT perfusion parameters between primary HCC and background liver parenchyma. Well-differentiated HCC showed significantly higher perfusion values (P <or= .05) than other grades. There was no significant difference in tumor perfusion between presence or absence of portal vein invasion or cirrhosis. Lymph node metastasis demonstrated lower values compared with metastases from other extrahepatic sites. There was no significant correlation between CT perfusion parameters and serum markers.

CONCLUSION

Results suggest that CT perfusion is a feasible and, from the limited data, reproducible technique for quantifying tumor vascularity and angiogenesis in advanced HCC.

Quantitative measurements of perfusion and permeability of oropharyngeal and oral cavity cancer, recurrent disease, and associated lymph nodes using first-pass contrast-enhanced computed tomography studies

OBJECTIVES

We sought to evaluate the routine clinical use of perfusion computed tomography in the detection and differentiation of primary and recurrent oropharynx and oral cavity tumors as well as of nodal disease.

MATERIALS AND METHODS

A total of 77 patients with primary cancer as well as suspected recurrent disease and lymph nodes were evaluated. A dynamic acquisition (4 x 6-mm slices) of the largest axial tumor surface was performed and the tumor blood flow (BF), blood volume (BV), and mean transit time (MTT) were calculated by using a modified deconvolution-based analysis taking into account the extravasation of the contrast agent for permeability surface area product imaging (PS). Tumor volume was calculated and region of interest analysis was performed on the pathologic and normal tissue.

RESULTS

The mean BF, BV, and PS values in the primary tumors (77.48 mL/min/100 g tissue; 5.29 mL/min; 13.33 mL/min/100 g tissue, respectively) were highly significantly different (P < 0.01) than those obtained in the normal structures. Mean MTT values (9.01 seconds) also were significantly lowered in the tumors compared with normal tissue (P < 0.05). There was no statistical difference in the perfusion values between the primary and the recurrent tumors. Recurrent disease could be differentiated on the basis of BF (P < 0.05) from tissue changes after chemo-radiation-treatment (mean BF: 69.71 versus 45.31 mL/min/100 g tissue, respectively). Differentiation of the lymph nodes was not possible by means of perfusion values. Tumor volume did not significantly correlate with any perfusion parameter.

CONCLUSIONS

Perfusion CT of oropharyngeal and oral cavity cancer in clinical routine is feasible and helps outlining the malignant tissue as well as differentiating recurrent disease from nonspecific post-therapeutic changes.