18F-2-deoxy-2-fluoro-D-glucose positron emission tomography, computed tomography, and magnetic resonance imaging for the detection of experimental colorectal liver metastases

During the treatment of colorectal liver metastases, evaluation of treatment efficacy is of the utmost importance for decision making. The aim of the present study was to explore the ability of preclinical imaging modalities to detect experimental liver metastases. Nine male Wag/Rij rats underwent a laparotomy with intraportal injection of CC531 tumor cells. On days 7, 10, and 14 after tumor induction, sequential positron emission tomography (PET), computed tomography (CT), and magnetic resonance imaging (MRI) scans were acquired of each rat. At each time point, three rats were euthanized and the metastases in the liver were documented histologically. Topographically, the liver was divided into eight segments and the image findings were compared on a segment-by-segment basis with the histopathologic findings. Sixty-four liver segments were analyzed, 20 of which contained tumor deposits. The overall sensitivity of PET, CT, and MRI was 30%, 25%, and 20%, respectively. For the detection of tumors with a histologic diameter exceeding 1 mm (n = 8), the sensitivity of PET, CT, and MRI was 63%, 38%, and 38%, respectively. The overall specificity of PET, CT, and MRI was 98%, 100%, and 93%, respectively. This study showed encouraging detectability and sensitivity for preclinical imaging of small liver tumors and provides valuable information on the imaging techniques for designing future protocols.     

A realistic utilization of nanotechnology in molecular imaging and targeted radiotherapy of solid tumors

Precise dose delivery to malignant tissue in radiotherapy is of paramount importance for treatment efficacy while minimizing morbidity of surrounding normal tissues. Current conventional imaging techniques, such as magnetic resonance imaging (MRI) and computerized tomography (CT), are used to define the three-dimensional shape and volume of the tumor for radiation therapy. In many cases, these radiographic imaging (RI) techniques are ambiguous or provide limited information with regard to tumor margins and histopathology. Molecular imaging (MI) modalities, such as positron emission tomography (PET) and single photon-emission computed-tomography (SPECT) that can characterize tumor tissue, are rapidly becoming routine in radiation therapy. However, their inherent low spatial resolution impedes tumor delineation for the purposes of radiation treatment planning. This review will focus on applications of nanotechnology to synergize imaging modalities in order to accurately highlight, as well as subsequently target, tumor cells. Furthermore, using such nano-agents for imaging, simultaneous coupling of novel therapeutics including radiosensitizers can be delivered specifically to the tumor to maximize tumor cell killing while sparing normal tissue.     

Renal cell -like carcinoma of the nasal cavity: a case report and review of the literature

Background

Sinonasal renal cell-like carcinoma (SRCLC) is an extremely rare low malignant tumor arising in the sinonasal tract, with histological mimicry of renal cell carcinoma.

Case presentation

We present a case of sinonasal renal cell-like carcinoma in a 63-year-old male patient. Computer tomography(CT) scanning revealed a soft tissue mass at the left nasal cavity and choana. Histologically, the predominant tumor architecture was follicular to glandular with intervening fibrous septa. The tumor cells were uniform cuboidal to polyhedral with abundant clear or eosinophilic cytoplasm. Immunohistochemically, the tumor cells were strongly positive for CK7, EMA, vimentin, SOX10, S-100, and focally positive for CA9. During 6 months of follow-up, there was no clinical or radiological evidence of recurrence or metastasis.

Conclusion

SRCLC has microscopic features which overlap with tumors that contain clear cells. Thus, several other tumors must be considered in the differential diagnosis of a tumor of the sinonasal region with clear cells, especially metastatic renal clear cell carcinoma. SRCLC is an indolent tumor and none of the reported SRCLC patients had metastatic disease.

     

An open environment CT-US fusion for tissue segmentation during interventional guidance

Therapeutic ultrasound (US) can be noninvasively focused to activate drugs, ablate tumors and deliver drugs beyond the blood brain barrier. However, well-controlled guidance of US therapy requires fusion with a navigational modality, such as magnetic resonance imaging (MRI) or X-ray computed tomography (CT). Here, we developed and validated tissue characterization using a fusion between US and CT. The performance of the CT/US fusion was quantified by the calibration error, target registration error and fiducial registration error. Met-1 tumors in the fat pads of 12 female FVB mice provided a model of developing breast cancer with which to evaluate CT-based tissue segmentation. Hounsfield units (HU) within the tumor and surrounding fat pad were quantified, validated with histology and segmented for parametric analysis (fat: −300 to 0 HU, protein-rich: 1 to 300 HU, and bone: HU>300). Our open source CT/US fusion system differentiated soft tissue, bone and fat with a spatial accuracy of ∼1 mm. Region of interest (ROI) analysis of the tumor and surrounding fat pad using a 1 mm² ROI resulted in mean HU of 68±44 within the tumor and −97±52 within the fat pad adjacent to the tumor (p<0.005). The tumor area measured by CT and histology was correlated (r² = 0.92), while the area designated as fat decreased with increasing tumor size (r² = 0.51). Analysis of CT and histology images of the tumor and surrounding fat pad revealed an average percentage of fat of 65.3% vs. 75.2%, 36.5% vs. 48.4%, and 31.6% vs. 38.5% for tumors <75 mm³, 75–150 mm³ and >150 mm³, respectively. Further, CT mapped bone-soft tissue interfaces near the acoustic beam during real-time imaging. Combined CT/US is a feasible method for guiding interventions by tracking the acoustic focus within a pre-acquired CT image volume and characterizing tissues proximal to and surrounding the acoustic focus.     

Computed tomography in the diagnosis of soft tissue neoplasms of the trunk and extremities]

Analysis of CT data on 213 patients with soft tissue and trunk tumors has shown that a majority of malignant and benign tumors have a similar picture (except lipoma). Features of the contours of a tumor and its inner structure do not permit the assessment of its nature. The only significant differential-diagnostic sign of malignant soft tissue tumors is destruction of an adjacent bone, noted in 17.6%. The majority of malignant and benign soft tissue tumors (70.9%) on CT scans look like a single node; recurrent tumors look multinodular (78.2%). Verification of soft tissue tumors, revealed by CT, should be done using morphological methods.     

PET for diagnosis and therapy of brain tumors

Main contribution of PET in the management of brain tumors is at the therapeutic level. Specific reasons explain this role of molecular imaging in the therapeutic management of brain tumors, especially gliomas. Gliomas are by nature infiltrating neoplasms and the interface between tumor and normal brain tissue may not be accurately defined on CT and MRI. Also, gliomas are often histologically heterogeneous with anaplastic areas evolving within a low-grade tumor, and the contrast-enhancement on CT or MRI does not represent a good marker for anaplastic tissue detection. Finally, assessment of tumor residue, recurrence or progression may be altered by different signals related to inflammation or adjuvant therapies, even on contrast-enhanced CT and MRI. These limitations of the conventional neuroimaging in delineating tumor and detecting anaplastic tissue lead to potential inaccuracy in lesion targeting at different steps of the management (diagnostic, surgical, and post-therapeutic stages). Molecular information provided by PET has proved helpful to supplement morphological imaging data in this context. ¹⁸F-FDG (FDG) and amino-acid tracers such as ¹¹C-methionine (MET), provides complementary metabolic data that are independent from the anatomical MR information. These tracers help in the definition of glioma extension, in the detection of anaplastic areas and in the postoperative follow-up. Additionally, PET data have an independent prognostic value. To take advantage of PET data in glioma treatment, PET might be integrated in the planning of image-guided biopsies, radiosurgery and resection.     

Current complex noninvasive diagnosis of parathyroid tumors

The diagnosis of bulky formations of the parathyroid glands (PTG) has become possible since current high-resolution techniques of visualization, such as ultrasound study (USS), computed tomography (CT), magnetic resonance imaging (MRI), were introduced into practice. The presence of clinical and/or laboratory signs of hyperparathyroidism (HPT) is a signal to initiate a goal-oriented search for abnormal PTG formations. The complex diagnosis of HPT involves the methods of detecting osteoporosis ranging from routine X-ray study of the hand and foot to more in-depth techniques: dichromatic X-ray absorptiometry (DXA) and quantitative CT (QCT). USS is an excellent method for screening if abnormal PTC changes are suspected; however, negative USS results in the presence of clinical and/or laboratory signs of HPT should not stop a diagnostic search. CT with intravenous contrast bolus specifies the site and structure of an formation, has some advantage in detecting retrosternal tumors. Due to its high tissue contrast, three-dimensional images, none ionizing radiation and osseous structural artefacts, MRI becomes a preferable tool for studying PTG when they are typically or atypically located. Needle biopsy is required when noninvasive methods cannot characterize the pattern of an abnormal PTG formation properly or their results are contradictory.     

Comparative characteristics of radiation imaging methods in the diagnosis of sacroiliitis

Patients with sacroiliac joint, injuries, ankylosing spondyloarthritis, or spondyloarthropathy of various genesis were examined. Pelvis x-ray, spiral computed tomography (CT), and magnetic resonance imaging (MRI) were performed. MRI was found to have advantages in the detection and evaluation of the pattern of detectable bone changes. It is inexpedient to use traditional x-ray study and CT for the detection of edematous-infiltrative changes in both osseous and fibrous and soft tissue elements of the joint since the sensitivity of these techniques is insufficient to detect. To analyze detectable changes, it is expedient to use a unified MRI protocol that involves the characteristics of osseous, fibrous, and soft tissue structures of the joint.     

Whole body diffusion for metastatic disease assessment in neuroendocrine carcinomas: comparison with OctreoScan(R) in two cases

ABSTRACT: Neuroendocrine tumor (NET) patients must be adequately staged in order to improve a multidisciplinary approach and optimal management for metastatic disease. Currently available imaging studies include somatostatin receptor scintigraphy, like OctreoScan(R), computed tomography (CT), scans and magnetic resonance imaging (MRI), which analyze vascular concentration and intravenous contrast enhancement for anatomic tumor localization. However, these techniques require high degree of expertise for interpretation and are limited by their availability, cost, reproducibility, and follow-up imaging comparisons. NETs significantly reduce water diffusion as compared to normal tissue. Diffusion-weighted imaging (DWI) in MRI has an advantageous contrast difference: the tumor is represented with high signal over a black normal surrounding background. The whole-body diffusion (WBD) technique has been suggested to be a useful test for detecting metastasis from various anatomic sites. In this article we report the use of DWI in MRI and WBD in two cases of metastatic pulmonary NET staging in comparison with OctreoScan(R) in order to illustrate the potential advantage of DWI and WBD in staging NETs.     

Current views on imaging of adrenal tumors.

Anatomical imaging modalities (such as computed tomography [CT] or magnetic resonance imaging [MRI]) and functional imaging modalities (that is, nuclear medicine) are used in the evaluation of adrenal glands. The use of CT (unenhanced, followed by contrast-enhanced) evaluation is the cornerstone of imaging of adrenal tumors. Attenuation values of less than 10 Hounsfield units at unenhanced CT are practically diagnostic for adenomas, while attenuation values of greater than 10 HU are not diagnostic of metastatic disease since non-metastatic disease is also a possibility. When lesions cannot be characterized adequately with CT, MRI evaluation (with T1 and T2-weighted sequences and chemical shift and fat-suppression refinements) is sought. Functional nuclear medicine imaging can be of utility in the evaluation of adrenal masses, more particularly for lesions not adequately characterized with CT and MRI. Nuclear medicine techniques are based on physiological and pathophysiological processes (cellular metabolism, tissue perfusion and local synthesis, uptake, storage of hormones and their receptors). Functional imaging aids initial preoperative staging, diagnostic evaluation of suspicious lesions, identification of metastatic or recurrent tumors, refining prognosis, and deciding on and predicting responses to therapy. [ (131)I]-6-iodomethyl norcholesterol scintigraphy can differentiate adenomas from carcinomas. Pheochromocytomas appear as areas of abnormal/increased [ (131)I]- and [ (123)I]-meta-iodobenzylguanidine uptake. Our experience has shown that [ (18)F]-fluorodopamine is an excellent agent for localizing adrenal and extra-adrenal pheochromocytomas.     

[18F]-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography of LAPC4-CR Castration-Resistant Prostate Cancer Xenograft Model in Soft Tissue Compartments

Preclinical xenograft models have contributed to advancing our understanding of the molecular basis of prostate cancer and to the development of targeted therapy. However, traditional preclinical in vivo techniques using caliper measurements and survival analysis evaluate the macroscopic tumor behavior, whereas tissue sampling disrupts the microenvironment and cannot be used for longitudinal studies in the same animal. Herein, we present an in vivo study of [¹⁸F]-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) designed to evaluate the metabolism within the microenvironment of LAPC4-CR, a unique murine model of castration-resistant prostate cancer. Mice bearing LAPC4-CR subcutaneous tumors were administered [¹⁸F]-FDG via intravenous injection. After a 60-minute distribution phase, the mice were imaged on a PET/CT scanner with submillimeter resolution; and the fused PET/CT images were analyzed to evaluate tumor size, location, and metabolism across the cohort of mice. The xenograft tumors showed [¹⁸F]-FDG uptake that was independent of tumor size and was significantly greater than uptake in skeletal muscle and liver in mice (Wilcoxon signed-rank P values of .0002 and .0002, respectively). [¹⁸F]-FDG metabolism of the LAPC4-CR tumors was 2.1 ± 0.8 ID/cm³*wt, with tumor to muscle ratio of 7.4 ± 4.7 and tumor to liver background ratio of 6.7 ± 2.3. Noninvasive molecular imaging techniques such as PET/CT can be used to probe the microenvironment of tumors in vivo. This study showed that [¹⁸F]-FDG-PET/CT could be used to image and assess glucose metabolism of LAPC4-CR xenografts in vivo. Further work can investigate the use of PET/CT to quantify the metabolic response of LAPC4-CR to novel agents and combination therapies using soft tissue and possibly bone compartment xenograft models.     

Practical vessel imaging by computed tomography in live transgenic mouse models for human tumors

Contrast-enhanced small-animal computed tomography is an economical and highly quantitative tool for serially examining tumor development in situ, for analyzing the network of blood vessels that nourish them, and for following the response of tumors to preclinical therapeutic intervention(s). We present practical considerations for visualizing the vascular network of transgenic mouse tumors. Using a long-acting iodinated triglyceride blood-pool contrast agent, we present optimized scanner acquisition parameters and volume-rendering techniques for examining the intermediate and large vessels of complex spontaneous tumors (e.g., alveolar rhabdomyosarcomas) in transgenic mice. Our findings indicate that multiple-frame, 360-720 view acquisitions were mandatory for clarifying bone and soft tissue from vessel contrast. This finding was consistent in visualizations using a one-dimensional transfer function where voxel color and opacity was assigned in proportion to CT value and a two-dimensional transfer function where voxel color and opacity was assigned in proportion to CT value and gradient magnitude. This study lays a groundwork for the qualitative and quantitative assessment of anti-angiogenesis preclinical studies using transgenic mice.     

Potentialities of new radiation technologies (ultrasonography, computed tomography, magnetic resonance imaging) in the diagnosis of endocrine diseases

In the paper providing the data available in the literature and many years' experience gained by the Department of the Moscow Regional Clinical Research Institute, the authors describe the potentialities of the currently available radiation techniques in the diagnosis of surgical endocrine diseases. The incidence of various organ dysfunctions is presented. The authors also consider the introscopic symptoms of various endocrinopathies and outline the common specific features of the ultrasound, computed tomographic, and magnetic resonance imaging pattern of individual masses (including adipose tissue cysts and tumors). Emphasis is laid on the leading role of ultrasonography (USG) in the diagnosis of thyroid and parathyroid diseases and on the priorities of computed tomography (CT) and magnetic resonance imaging (MRI) in visualIzing the abnormal thymus, mediastinally ectopic glands, and pituitary tumors. The capacities of each technique in the diagnosis of endocrine space lesions of the pancreas and adrenals are defined. The increase in the frequency of endocrine abnormalities accidentally identified at USG, CT, and MRI, which is noted in the paper, fosters the development of new trends in endocrinology and points to the need for screening surveys (particularly patients who live in poor environmental areas).     

Accuracy of CT scans in identifying tumor tissue

The authors present their experience with stereotactic biopsy of brain tumors. Biopsies were obtained sequentially at different depths from the center of the tumor according to coordinates derived from computerized tomography (CT). Biopsies were obtained from 23 brain tumors: 17 gliomas, 5 metastases, and 1 lymphoma. In all a total of 137 biopsies were studied from both enhancing and nonenhancing areas. The tumor yield from these biopsies was 68 and 73%, respectively. It appears that tumor tissue may be obtained from both the enhancing periphery as well as the nonenhancing center of tumors.     

Multimodality imaging of somatostatin receptor-positive tumors with nuclear and bioluminescence imaging

Multimodal bioluminescence (BLI) and single-photon emission computed tomography/computed tomography (SPECT/CT) imaging were investigated as means to monitor somatostatin receptor subtype 2 (SST2)-positive neuroendocrine tumors as both a subcutaneously implanted and a liver metastasis animal model in mice and rats. Ultimately, such a model will be of use for studying SST2-targeted peptide receptor radionuclide therapy (PRRT). CA20948 cells were transfected with a green fluorescent protein/luciferase plasmid construct. Cells were inoculated subcutaneously in the shoulder of nude mice: nontransfected cells in the left shoulder and transfected cells in the right shoulder. BLI, SPECT/CT imaging, biodistribution analysis, and ex vivo autoradiography of the tumors were performed. BLI and SPECT/CT imaging were also performed on an intrahepatic tumor model in the rat. Caliper volume measurement of transfected tumors could be correlated with BLI measurements (R2 = .76). SPECT/CT imaging showed high levels of accumulation of 111In-DTPA-octreotide in control and transfected tumors, which was confirmed by biodistribution analysis and autoradiography. Subcapsular inoculation of transfected cells in rat liver resulted in an intrahepatic tumor, which could be visualized by both SPECT/CT and BLI. Transfection of CA20948 tumor cells did not alter the growth properties of the cell line or the expression of SST2. Transfected tumors could be clearly visualized by BLI and SPECT/CT imaging. The transfected SST2-positive tumor cell line could represent a novel preclinical model for tumor monitoring in studies that aim at further optimizing PRRT for neuroendocrine tumors.     

Magnetic resonance tomography in the diagnosis of lung metastases in the mediastinum and thorax

The results of MRI in 81 patients with morphologically verified lung cancer, mainly Stages IIIA and IIIB, were analyzed. They were compared with CT data in 37 cases and surgical findings in 28. MRI was performed by using Magnaview 0.04 T and Vectra 0.5 T apparatus in the T1- and T2-weighted SE and PC sequences as well in the fat-suppression mode. Thoracic metastases were evaluated from the direct signs tumor spread into the adjacent tissue and vessels. The criteria for the involvement of lymph nodes were their over 1-cm enlargement and characteristic changes in the intensity of signals from them. CT was found to yield less information on pleural, pericardial, and vascular invasion (66-75% sensitivity). MRI detected this type of cancer spread (88-94% sensitivity). Both techniques have nearly equal sensitivities in revealing intrathoracic lymphadenopathy. The interpretation of MRI data did not depend on the voltage of a magnetic field. It is recommended that MRI should be made after CT when there is a need for assessing large vessels or for making clear the data that remain open to question following CT.     

Transposition of target information from the magnetic resonance and computed tomography scan images to conventional X-ray stereotactic space

A technique to apply reconstructed X-ray computed tomography (CT) and magnetic resonance imaging (MRI) for target determination in stereotactic Bragg peak proton beam therapy of intracranial lesions was developed. Twenty-one benign intracranial tumors and vascular abnormalities were managed using this technique. Clinical features of these lesions, as well as targeting problems associated with the MRI and CT image interpretation, are presented.     

Noncontrast computed tomography in the diagnosis of tumors of the major salivary glands

Non-contrast computed tomography (CT) of the major salivary glands was made in 127 patients, which revealed 95 space-occupying lesions (88 intraglandular and 7 extraglandular ones). Pleomorphic tumors of the parotid glands are solitary, round, high-density (29.6 +/- 4.2 HU) masses with well-defined, smooth margins. Salivary cysts were characterized by the presence of a dense capsule; the density of cyst contents was 8.0 +/- 2.0 HU. Salivary lipomas had a characteristic tomographic pattern due to the presence of adipose tissue; the lipoma density was -108.3 +/- 7.8 HU. Malignant parotid tumors were characterized by the presence of higher-density masses with irregular shapes and ill-defined, indistinct margins. Benign submandibular gland tumors had no well-defined margins that separated the tumor from the gland; the density of a tumor matched that of the parenchyma; the mean tumor size was 3.6 +/- 1.3 cm; there was an increase in the sizes of the gland as compared to those of the contralateral gland, as well as a displacement of the adjacent soft tissues. Malignant submandibular gland neoplasms tumors were characterized by the presence of inhomogenous lower-density masses with irregular shapes. Enlarged paraglandular lymph nodes were observed. The sensitivity, specificity, and accuracy of native CT in diagnosing space-occupying lesions of the salivary glands were 97.6, 96.4, and 97.6%, respectively.     

Comparison of the diagnostic capacities of imaging methods for childhood hemangiomas

The diagnostic capacities of three imaging methods: B-mode ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) in orbital hemangiomas in babies were compared. Orbital ultrasound, computed tomography, and MRI scans were examined in 358, 384, and 48 babies, respectively. Their mean age was 6.7 months. Out of three techniques, ultrasound scanning proved to be of less informative value. MRI and CT were much more informative although each of them had advantages and limitations. The authors give some preference to CT despite its ionization.