Significant Contrast Enhancement Research Articles

Citrate stabilized maghemite hydrosol with controllable MRI contrast: Key role of nanoparticle size

In this study, we have synthetized a series of citric acid stabilized superparamagnetic iron oxide nanoparticles (CA-SPIONs) with different core sizes in an automated chemical reactor with high repeatability of the nanoparticle size and chemical composition. The prepared CA-SPIONs are highly crystalline spherical-shaped particles with the diameters of 3.5 ± 0.7, 6 ± 1, 9 ± 1, and 12 ± 2 nm. The valent state of iron oxide was determined by a combination of X-ray photoelectron spectroscopy, UV–Vis spectroscopy, and Mössbauer studies, which confirmed predominantly maghemite formation. Under normal conditions, these nanoparticles exhibit no coercive force and no hysteresis, while saturation magnetization increases from 2 to 61 emu/g along with the increasing core size. Both longitudinal (r1) and transverse (r2) relaxivities of maghemite hydrosols with different nanoparticle sizes were measured and compared with the same data for the commercial Gd-complex (Gadovist). Magnetic circular dichroism spectroscopy indicated that aggregation occurs in magnetic field, but 9 nm samples slightly aggregate in the fields above 1.0 T, whereas 3.5 nm colloids are stable and do not exhibit aggregation behavior even at 1.5 T. The obtained series were examined in phantom test in clinical 1.5 T MRI scanner, which showed that increasing the particle core size resulted in an enhanced T2 contrast, while T1 contrast declined. Finally, the smallest CA-SPION colloid nanoparticles with the size of 3.5 nm exhibited significant T1 contrast enhancement, comparable with the commercial Gd-complex in water and human plasma as well. The maghemite hydrosol formed by nanoparticles with 3.5 nm size thus has a promising future as a T1 MRI contrast agent.

A Facile Approach to Producing Liposomal J-Aggregates of Indocyanine Green with Diagnostic and Therapeutic Potential.

Liposomal J-Aggregates of Indocyanine Green (L-JA) can serve as a biocompatible and biodegradable nanoparticle for photoacoustic imaging and photothermal therapy. When compared to monomeric IcG, L-JA are characterized by longer circulation, improved photostability, elevated absorption at longer wavelengths, and increased photoacoustic signal generation. However, the documented methods for production of L-JA vary widely. We developed an approach to efficiently form IcG J-aggregates (IcG-JA) directly in liposomes at elevated temperatures. Aggregating within fully formed liposomes ensures particle uniformity and allows for control of J-aggregate size. L-JA have unique properties compared to IcG. L-JA provide significant contrast enhancement in photoacoustic images for up to 24 hours after injection, while IcG and unencapsulated IcG-JA are cleared within an hour. L-JA allow for more accurate photoacoustic-based sO2 estimation and particle tracking compared to IcG. Furthermore, photothermal heating of L-JA with an 852nm laser is demonstrated to be more effective at lower laser powers than conventional 808nm lasers for the first time. The presented technique offers an avenue for formulating a multi-faceted contrast agent for photoacoustic imaging and photothermal therapy that offers significant advantages over other conventional agents.

Noninvasive Photothermal Therapy of Nasopharyngeal Cancer Guided by High Efficiency Optical-Absorption Nanomaterial Enhanced by NIR-II Photoacoustic Imaging.

Photothermal therapy (PTT) guided by photoacoustic imaging (PAI) using nanoplatforms has emerged as a promising strategy for cancer treatment due to its efficiency and accuracy. This study aimed to develop and synthesize novel second near-infrared region (NIR-II) absorption-conjugated polymer acceptor acrylate-substituted thiadiazoloquinoxaline-diketopyrrolopyrrole polymers (PATQ-DPP) designed specifically as photothermal and imaging contrast agents for nasopharyngeal carcinoma (NPC). The PATQ-DPP nanoparticles were synthesized and characterized for their optical properties, including low optical band gaps. Their potential as PTT agents and imaging contrast agents for NPC was evaluated both in vitro and in vivo. The accumulation of nanoparticles at tumor sites was assessed post-injection, and the efficacy of PTT under near-infrared laser irradiation was investigated in a mouse model of NPC. Experimental results indicated that the PATQ-DPP nanoparticles exhibited significant photoacoustic contrast enhancement and favorable PTT performance. Safety and non-toxicity evaluations confirmed the biocompatibility of these nanoparticles. In vivo studies showed that PATQ-DPP nanoparticles effectively accumulated at NPC tumor sites and demonstrated excellent tumor growth inhibition upon exposure to near-infrared laser irradiation. Notably, complete elimination of nasopharyngeal tumors was observed within 18 days following PTT. The findings suggest that PATQ-DPP nanoparticles are a promising theranostic agent for NIR-II PAI and PTT of tumors. This innovative approach utilizing PATQ-DPP nanoparticles provides a powerful tool for the early diagnosis and precise treatment of NPC, offering a new avenue in the management of this challenging malignancy.

Identification of exfoliated monolayer hexagonal boron nitride films with a digital color camera under white light illumination

Optical microscopy with white light illumination has been employed when obtaining exfoliated monolayer hexagonal boron nitride (1L hBN) films from a large number of randomly placed films on a substrate. However, real-time observation of 1L hBN using a color camera under white light illumination remains challenging since hBN is transparent in the visible wavelength range. The poor optical constant of 1L hBN films in microphotographs is significantly improved using a Si substrate coated with a SiN x thin-film (SiN x /Si). When observing hBN thin films on SiN x /Si using a color digital camera in an optical microscope under white light illumination, the clarity of the captured color images depends on the thickness of the SiN x film (d). For real-time direct observation, the d was optimized based on quantitative chromatic studies tailored to Bayer filters of a color image sensor. Through image simulation, it was determined that the color difference between 1L hBN and the bare substrate is maximized at d = 59 or 70 nm, which was experimentally verified. The SiN x /Si with optimized d values visualized 1L hBN films without requiring significant contrast enhancement via image processing under white light illumination in real-time. Furthermore, the captured color photographs facilitate the reliable determination of the number of layers in few-layer hBN films using the contrast of the green channel of the images.

Superparamagnetic Iron Oxide-Erastin-Polyethylene Glycol Nanotherapeutic Platform: A Ferroptosis-Based Approach for the Integrated Diagnosis and Treatment of Nasopharyngeal Cancer.

Erastin can induce ferroptosis in tumor cells as an effective small molecule inhibitor. However, its application is hampered by a lack of water solubility. This study investigated the effects of superparamagnetic iron oxide (SPIO)-erastin-polyethylene glycol (PEG) nanoparticles prepared by loading SPIO-PEG nanoparticles with erastin on ferroptosis. SPIO-erastin-PEG nanoparticles exhibited square and spherical shapes with good dispersibility. The zeta potential and hydrodynamic size of SPIO-erastin-PEG were measured as (-37.68 ± 2.706) mV and (45.75 ± 18.88) nm, respectively. On T2-weighted imaging, the nanosystem showed significant contrast enhancement compared to no-enhancement magnetic resonance imaging (MRI). SPIO-erastin-PEG induced ferroptosis by increasing reactive oxygen species and iron content and promoting the accumulation of lipid peroxides and the degradation of glutathione peroxidase 4. Pharmacokinetic experiments revealed a half-life of 1.25 ± 0.05 h for the SPIO-erastin-PEG solution in circulation. Moreover, significant antitumorigenic effects of SPIO-erastin-PEG have been demonstrated in 5-8F cells and mouse-bearing tumors. These results indicated that the synthesized SPIO-erastin-PEG nanoplatform could induce ferroptosis effects in vitro and in vivo while exhibiting favorable physical characteristics. This approach may provide a new strategy for theranostic nanoplatform for nasopharyngeal cancer.

Primary central nervous system lymphoma: Imaging features and differential diagnosis.

Primary central nervous system lymphoma (PCNSL) represents 5% of malignant primary brain tumors. The clinical presentation typically includes focal neurological symptoms, increased intracranial pressure, seizures, and psychiatric symptoms. Although histological examination remains the gold standard for diagnostic confirmation, non-invasive imaging plays a crucial role for the diagnosis. In immunocompetent individuals, PCNSL usually appears as a single, well-defined, supratentorial lesion with a predilection for periventricular areas, iso- or hypointense on T1- and T2-weighted magnetic resonance imaging, with restricted diffusion, slightly increased perfusion, and homogenous gadolinium-enhancement. Differential diagnoses include high-grade glioma and pseudotumoral demyelinating disease. In immunocompromised patients, PCNSL may present as multiple lesions, with a higher likelihood of hemorrhage and necrosis and less restricted diffusion than immunocompetent individuals. Differential diagnoses include neurotoxoplasmosis, progressive multifocal leukoencephalopathy, and cerebral abscess. Atypical forms of lymphoma are characterized by extra-axial lymphoma, lymphomatosis cerebri, and intravascular lymphoma. Extra-axial lymphoma presents as single or multiple extra-axial dural lesions with diffuse leptomeningeal contrast-enhancement. Lymphomatosis cerebri appears as an infiltrative and symmetric lesion, primarily affecting deep white matter and basal ganglia, appearing hyperintense on T2-weighted imaging, without significant contrast-enhancement or perfusion changes. Intravascular lymphoma presents as multiple rounded or oval-shaped "infarct-like" lesions, located cortically or subcortically. This study aims to highlight the imaging characteristics of PCNSL, focusing on magnetic resonance imaging and its differential diagnosis.

Canine preclinical safety evaluation of a multimodal nanoparticle agent (Nanotrast-CF800) for image-guided cancer surgery.

Surgical oncology often requires the use of contrast-enhanced cross-sectional imaging preoperatively to characterize solitary tumours and identify sentinel lymph nodes. Intraoperative optical guidance can effectively aid tissue-sparing tumour excision and locate sentinel lymph nodes. Nanotrast-CF800 (CF800) is a novel dual-modality contrast agent, which co-encapsulates iohexol and indocyanine green (ICG) within a liposomal nanoparticle. It was developed for preoperative and intraoperative imaging of solitary tumours and sentinel lymph node mapping and its efficacy has been demonstrated in preclinical animal models (Zheng et al. 2015). The objective of this study is to evaluate the safety profile of CF800 following intravenous administration in healthy dogs. Six research dogs were randomized into two groups. Group 1 received a low dose (1 mL/kg) and group 2 received a high dose (5 mL/kg). Dogs were placed under general anesthesia and a continuous rate infusion of CF800 was administered based on group allocation. Physiologic parameters including heart rate, respiratory rate, direct arterial blood pressure, cardiac output, and temperature were measured at set time points. Plasma concentrations of iohexol, ICG, and histamine were measured at set time points. Dogs underwent whole body computed tomography scans pre-injection, 2-, and 7-days post-injection (p.i.). Contrast enhancement was measured in select organ systems and great vessels at each time point. There were no significant changes in physiologic parameters following IV infusion of CF800 in all dogs. Plasma iohexol and ICG concentrations peaked at 1 day p.i., while histamine concentrations peaked at 30 minutes p.i. Significant contrast enhancement was noted within the liver, heart, aorta, and caudal vena cava on day 2 p.i., which was significantly different compared to baseline. Prolonged contrast retention within the liver was identified. Intravenous administration of CF800 was safe to use in healthy dogs with no significant systemic adverse effects.

Slow-growing WNT medulloblastoma with atypical magnetic resonance imaging findings: illustrative case.

Medulloblastomas, with four molecular subgroups, are generally rapid-growing tumors with significant contrast enhancement and well-defined margins. However, each subgroup's clinical features, including disease time course and imaging characteristics, are not well defined. The authors describe the case of a 15-year-old female who presented with a 7-month history of impaired left-hand movement and was found to have a lesion on the dorsal side of the fourth ventricle. T2-weighted magnetic resonance imaging (MRI) at the patient's first presentation showed diffuse hyperintense signal without apparent mass, and gadolinium-enhanced T1-weighted imaging showed very slight contrast enhancement. In 1 month, her symptoms progressed, and follow-up MRI revealed an increase in the size of the lesion, showing greater diffusion restriction and contrast enhancement. She underwent gross-total resection, and pathology was consistent with classic medulloblastoma. Genetic analysis of the tumor confirmed the wingless (WNT) molecular subgroup. Adjuvant chemotherapy and proton beam therapy were performed. At the 18-month follow-up, MRI showed no recurrence of disease. Slow-growing medulloblastoma is very rare and not known to be associated with a specific molecular subgroup. Here, the authors report a case of slow-growing WNT medulloblastoma, indicating that slow growth may be a feature of this subgroup.

Contrast administration via ultrasound-guided injection of the cranial tibial artery results in contrast enhancement of the soft tissues of the metatarsus in horses undergoing CT.

Delivery of mesenchymal stem cells (MSC) via intravascular techniques to treat diffuse and/or inaccessible soft tissue injuries has grown in popularity. The purpose of the current prospective, analytical pilot study was to utilize CT to validate this novel technique and provide additional evidence to support its use for injectate delivery to specific soft tissue structures. Of particular interest was the proximal suspensory ligament, which presents a challenging injection target. Six adult horses without lameness underwent CT of the distal hindlimbs. Scans were obtained prior to ultrasound-guided catheterization of the cranial tibial artery, in addition to early and delayed scans acquired following intra-arterial contrast administration. Region of interest analysis of the superficial and deep digital flexor tendons and suspensory ligament was used to assess contrast enhancement within these structures. Linear mixed models were used to determine statistical significance. Significant (P<0.05) mean contrast enhancement was seen in all postinjection time points in all soft tissue structures of interest. This indicates that ultrasound-guided injection of the cranial tibial artery results in perfusion of injectate throughout the distal hind limb, including the major soft tissue structures of the metatarsus. This provides further support for this technique as a method of MSC delivery to multifocal or inaccessible injury of these structures, including the proximal suspensory ligament.

Magnetic Resonance Imaging Features and Misdiagnosis of Spinal Epidural Cavernous Hemangioma.

Spinal epidural cavernous hemangiomas (SECHs) are rare, and merely a few have previously been described in case reports. The present study aims to explore the magnetic resonance imaging (MRI) features of SECHs and analyze the causes of their preoperative misdiagnosis. The present retrospective study included 11 patients (three male and eight female patients, mean age ± standard deviation: 47.55±17.39 years old) with histopathologically confirmed SECH between January 2015 and April 2021. The MRI features of SECH were analyzed by two radiologists. The cervical, thoracic and thoracolumbar segments were involved in 2, 7 and 2 patients, respectively. All lesions grew along the long axis of the spine. The tumors were shuttle-shaped in six patients, oval in two patients, pseudopodia-shaped in one patient, clamp-shaped in one patient, and growing outward along the intervertebral foramen in one patient. Nine SECHs had relatively uniform isointense or hypointense T1-weighted imaging (T1WI) and hyperintense T2-weighted imaging (T2WI) signals. On the T2WI, filamentary low-signal shadows (i.e., the hairline or grid sign) with significant contrast enhancement and asymptotic strengthening were observed. Two SECHs had mixed high and low signals on T1WI and T2WI, with significant heterogeneous enhancement, hemorrhage, and hemosiderin deposition. The SECH was misdiagnosed as meningioma, neurofibromatosis and schwannoma in 1, 1 and 4 patients, respectively, while this was not diagnosed in one patient. The preoperative diagnosis was correct in merely approximately 36% of patients. Among the four patients with a correct preoperative diagnosis, hemosiderin deposition was found in three patients and small tortuous vascular shadows were found in one patient. SECH presents as a long spindle-shaped mass, and the "'pen cap sign" is common at the lesion edges. SECH also exhibits a hairline or grid sign on T2WI. Furthermore, some lesions present with hemorrhage and hemosiderin deposition. Therefore, the hairline, grid sign and hemosiderin deposition are valuable diagnostic features of SECH.

CD40-targeting magnetic nanoparticles for MRI/optical dual-modality molecular imaging of vulnerable atherosclerotic plaques

Background and aimsAcute coronary syndrome caused by vulnerable plaque rupture or erosion is a leading cause of death worldwide. CD40 has been reported to be highly expressed in atherosclerotic plaques and closely related to plaque stability. Therefore, CD40 is expected to be a potential target for the molecular imaging of vulnerable plaques in atherosclerosis. We aimed to design a CD40-targeted magnetic resonance imaging (MRI)/optical multimodal molecular imaging probe and explore its ability to detect and target vulnerable atherosclerotic plaques. MethodsCD40-Cy5.5 superparamagnetic iron oxide nanoparticles (CD40-Cy5.5-SPIONs), which comprise a CD40-targeting multimodal imaging contrast agent, were constructed by conjugating CD40 antibody and Cy5.5-N-hydroxysuccinimide ester with SPIONs. During this in vitro study, we observed the binding ability of CD40-Cy5.5-SPIONs with RAW 264.7 cells and mouse aortic vascular smooth muscle cells (MOVAS) after different treatments, using confocal fluorescence microscopy and Prussian blue staining. An in vivo study involving ApoE−/− mice fed a high-fat diet for 24–28 weeks was performed.24 h after intravenous injection of CD40-Cy5.5-SPIONs, fluorescence imaging and MRI were performed. ResultsCD40-Cy5.5-SPIONs bind specifically to tumor necrosis factor (TNF)-α-treated macrophages and smooth muscle cells. Fluorescence imaging results showed that, compared with the control group and the atherosclerosis group injected with non-specific bovine serum albumin (BSA)-Cy5.5-SPIONs, the atherosclerotic group injected with CD40-Cy5.5-SPIONs had a stronger fluorescence signal. T2-weighted images showed that the carotid arteries of atherosclerotic mice injected with CD40-Cy5.5-SPIONs had a significant substantial T2 contrast enhancement effect. ConclusionsCD40-Cy5.5-SPIONs could potentially serve as an effective MRI/optical probe for vulnerable atherosclerotic plaques during non-invasive detection.

The peri-olfactory pathway: an "e-scent-ial" route for cerebrospinal fluid clearance?

The peri-olfactory pathway: an "e-scent-ial" route for cerebrospinal fluid clearance?

UTERINE SCAR ENDOMETRIOMA: A CASE REPORT

Introduction And Importance: Uterine scar endometriosis is a rare form of endometriosis due to previous surgical scars from obstetrical and gynecological procedures. Its challenging diagnosis to make. A 34- Case presentation: year-old multiparous female presented with intermittent lower abdominal pain and inter-menstrual bleeding for the past 4 months .Ultrasound revealed a heterogenous, predominantly hyperechoic lesion measuring 40x51x54mm in the myometrium of anterior lower uterine segment extending to cervical stroma. MRI revealed a lobulated mass lesion in the anterior wall of lower uterine segment, extending along the scar niche. The lesion showed heterogenous hyperintense signal on T2WI with hyperintense signal on T1WI (sub-acute blood). No significant post contrast enhancement was seen. Impression of a scar site endometriosis was made. Subsequently the patient underwent diagnostic laparoscopy, which revealed a lobulated cystic mass in the lower uterine segment, with oozing of chocolate brown material on compression. As the mass was deep-seated in the lower uterine segment, a laparotomy was decided upon and total abdominal hysterectomy with varian conservation was performed. Histopathology confirmed the diagnosis of endometriosis. Conclusion: In any women of reproductive age with lower abdominal pain and solid appearing mass lesion at the uterine scar from previous obstetric or gynaecologic surgery, uterine scar endometriosis should be considered.

Iodinated Contrast Enhancement of Breast Cancer on Prone Multidetector Computed Tomography-Preliminary Findings.

Contrast-enhanced breast imaging has gained increasing importance in the diagnosis and management of breast cancer. The aim of this study was to assess breast cancer enhancement after contrast administration on prone multidetector computed tomography (MDCT). This retrospective, unicentric, institutional review board-approved study included patients with newly diagnosed breast cancer who were submitted to contrast-enhanced MDCT in prone position, with image acquisition before and after nonionic iodinated contrast administration. Sixty breast cancer patients aged between 31 and 74 years (mean, 49 years) were included. Most patients (n = 50, 83.3%) had no special type invasive breast carcinoma and luminal subtype (n = 45, 75%). All index breast tumors were identified on prone MDCT. Forty-three cases (70.5%) presented as mass, 13 (21.3%) as nonmass enhancement and 4 (6.6%) as both mass and nonmass enhancement. Mean tumor density was 37.8 HU and 87.9 HU on precontrast and postcontrast images, respectively. Mean contrast enhancement was 50.2 HU (range, 20-109 HU). There were no statistically significant differences in tumor enhancement according to histological type, molecular subtype, nuclear grade, tumor size, or imaging presentation. Our results show that breast cancer usually can be identified and have significant contrast enhancement on prone MDCT images. This method could be used as an alternative when other contrast-enhanced breast imaging methods are not available.

P39 ATRIAL MASS IN HEART TRANSPLANTED PATIENT WITH CLINICAL HISTORY OF LYMPHOMA

Abstract Atrial thrombosis is an uncommon complication of cardiac transplant, especially when performed with standard technique. Pathogenetic mechanisms might involve atrial anatomy distortion and abnormalities in its contractile function, which induce flow stasis and thrombus formation, mostly on the surgical suture. A 77–year–old man underwent orthotopic heart transplantation in 2000 for post–ischemic dilated cardiomyopathy. In 2019 he was diagnosed with diffuse large B–cell lymphoma treated with chemotherapy. On March 2021, during follow up period, he had a total body CT scan which showed a submandibular space–occupying lesion, likely as a disease recurrence, and a large atrial mass (30x50 mm). For this reason, he was admitted to the emergency department. Echocardiography documented a massive hyperechogenic formation in an enlarged left atrium. In order to rule out a neoplastic nature, a cardiac CMR was performed, confirming the presence of an oval mass adhering to the posterior left atrial wall with partial involvement of pulmonary veins ostia, with inhomogeneous isointense signal on T1–weighted sequences and hyper–isointense signal on T2–weighted sequences, without significant contrast enhancement, likely representing an endoluminal thrombotic formation. Given the patient’s clinical status and his hemodynamic stability, a surgical excision was deferred. The patient was discharged on oral anticoagulant therapy with Warfarin (INR target 2–3). Three months later, a chest CT showed a meaningful mass reduction (11x18mm), which was no longer visible at echocardiography. About 9 months later, complete disappearance of the atrial mass was found at a CT scan. According to scientific literature, differential diagnosis of a newly discovered atrial mass in a transplanted heart includes thrombosis or neoplasia. Thrombosis occurs usually early after surgery, but due to promoting factors, it can arise after many years. The most likely triggering condition is an acquired prothrombotic status: in our case the likely lymphoma recurrence may have led to thrombogenesis. In order to exclude with confidence cardiac metastasis, histological examination would have been necessary. Nevertheless, the meaningful mass reduction, as early as three months after starting oral anticoagulation, and its disappearance nine months after, strongly suggests for atrial thrombosis.

Impact of TOF on Brain PET With Short-Lived 11C-Labeled Tracers Among Suspected Patients With AD/PD: Using Hybrid PET/MRI.

ObjectiveTo explore the impact of the time-of-flight (TOF) reconstruction on brain PET with short-lived 11C-labeled tracers in PET magnetic resonance (PET/MR) brain images among suspected patients with Alzheimer's and Parkinson's disease (AD/PD).MethodsPatients who underwent 11C-2-ß-carbomethoxy-3-b-(4-fluorophenyl) tropane (11C-CFT) and 2-(4-N-[11C] methylaminophenyl)-6-hydroxybenzothiazole (11C-PiB) PET/MRI were retrospectively included in the study. Each PET LIST mode data were reconstructed with and without the TOF reconstruction algorithm. Standard uptake values (SUVs) of Caudate Nucleus (CN), Putamen (PU), and Whole-brain (WB) were measured. TOF and non-TOF SUVs were assessed by using paired t-test. Standard formulas were applied to measure contrast, signal-to-noise ratio (SNR), and percentage relative average difference of SUVs (%RAD-SUVs).ResultsTotal 75 patients were included with the median age (years) and body mass index (BMI-kg/m2) of 60.2 ± 10.9 years and 23.9 ± 3.7 kg/m2 in 11C-CFT (n = 41) and 62.2 ± 6.8 years and 24.7 ± 2.9 kg/m2 in 11C-PiB (n = 34), respectively. Higher average SUVs and positive %RAD-SUVs were observed in CN and PU in TOF compared with non-TOF reconstructions for the two 11C-labeled radiotracers. Differences of SUVmean were significant (p < 0.05) in CN and PU for both 11C-labeled radiotracers. SUVmax was enhanced significantly in CN and PU for 11C-CFT and CN for 11C-PiB, but not in PU. Significant contrast enhancement was observed in PU for both 11C-labeled radiotracers, whereas SNR gain was significant in PU, only for 11C-PiB in TOF reconstruction.ConclusionTime-of-flight leads to a better signal vs. noise trade-off than non-TOF in 11C-labeled tracers between CN and PU, improving the SUVs, contrast, and SNR, which were valuable for reducing injected radiation dose. Improved timing resolution aided the rapid decay rate of short-lived 11C-labeled tracers, and it shortened the scan time, increasing the patient comfort, and reducing the motion artifact among patients with AD/PD. However, one should adopt the combined TOF algorithm with caution for the quantitative analysis because it has different effects on the SUVmax, contrast, and SNR of different brain regions.

Magnetic Resonance Imaging in the Contemporary Management of Medulloblastoma: Current and Emerging Applications.

Medulloblastoma, the most common malignant primary brain tumor in children, is now considered to comprise of four distinct molecular subgroups-wingless (WNT), sonic hedgehog (SHH), Group 3, and Group 4 medulloblastoma, each associated with distinct developmental origins, unique transcriptional profiles, diverse phenotypes, and variable clinical behavior. Due to its exquisite anatomic resolution, multiparametric nature, and ability to image the entire craniospinal axis, magnetic resonance imaging (MRI) is the preferred and recommended first-line imaging modality for suspected brain tumors including medulloblastoma. Preoperative MRI can reliably differentiate medulloblastoma from other common childhood posterior fossa masses such as ependymoma, pilocytic astrocytoma, and brainstem glioma. On T1-weighted images, medulloblastoma is generally iso- to hypointense, while on T2-weighted images, the densely packed cellular component of the tumor is significantly hypointense and displays restricted diffusion on diffusion-weighted imaging. Following intravenous gadolinium, medulloblastoma shows significant but variable and heterogeneous contrast enhancement. Given the propensity of neuraxial spread in medulloblastoma, sagittal fat-suppressed T1-postcontrast spinal MRI is recommended to rule out leptomeningeal metastases for accurate staging. Following neurosurgical excision, postoperative MRI done within 24-48h confirms the extent of resection, accurately quantifying residual tumor burden imperative for risk assignment. Post-treatment MRI is needed to assess response and effectiveness of adjuvant radiotherapy and systemic chemotherapy. After completion of planned therapy, surveillance MRI is recommended periodically on follow-up for early detection of recurrence for timely institution of salvage therapy, as well as for monitoring treatment-related late complications. Recent studies suggest that preoperative MRI can reliably identify SHH and Group 4 medulloblastoma but has suboptimal predictive accuracy for WNT and Group 3 tumors. In this review, we focus on the role of MRI in the diagnosis, staging, and quantifying residual disease; post-treatment response assessment; and periodic surveillance, and provide a brief summary on radiogenomics in the contemporary management of medulloblastoma.

Synthetic Antiferromagnetic Gold Nanoparticles as Bimodal Contrast Agents in MRI and CT-An Experimental In Vitro and In Vivo Study.

The use of multimodal contrast agents can potentially overcome the intrinsic limitations of individual imaging methods. We have validated synthetic antiferromagnetic nanoparticles (SAF-NPs) as bimodal contrast agents for in vitro cell labeling and in vivo cell tracking using magnetic resonance imaging (MRI) and computed tomography (CT). SAF-NP-labeled cells showed high contrast in MRI phantom studies (r2* = 712 s−1 mM−1), while pelleted cells showed clear contrast enhancement in CT. After intravenous SAF-NP injection, nanoparticles accumulated in the liver and spleen, as visualized in vivo by significant MRI contrast enhancement. Intravenous injection of SAF-NP-labeled cells resulted in cell accumulation in the lungs, which was clearly detectable by using CT but not by using MRI. SAF-NPs proved to be very efficient cell labeling agents for complementary MRI- and CT-based cell tracking. Bimodal monitoring of SAF-NP labeled cells is in particular of interest for applications where the applied imaging methods are not able to visualize the particles and/or cells in all organs.

Lipoma in olecranon bursa: A case report

We report a case of a 55-year-old male patient who presented with swelling over his right elbow of 5-year duration. An ultrasound examination revealed an echogenic mass within the olecranon bursa. On magnetic resonance imaging, the mass revealed the signal intensity of fat, and it was attached to the bursal lining by means of a pedicle. There was no restriction on diffusion-weighted images and no significant contrast enhancement. Excision was performed under local anesthesia. The excised specimen revealed mature fat cells on histopathology.

Prediction of Intraoperative Fluorescence of Brain Gliomas: Correlation between Tumor Blood Flow and the Fluorescence.

Introduction: The prediction of the fluorescent effect of 5-aminolevulinic acid (5-ALA) in patients with diffuse gliomas can improve the selection of patients. The degree of enhancement of gliomas has been reported to predict 5-ALA fluorescence, while, at the same time, rarer cases of fluorescence have been described in non-enhancing gliomas. Perfusion studies, in particular arterial spin labeling perfusion, have demonstrated high efficiency in determining the degree of malignancy of brain gliomas and may be better for predicting fluorescence than contrast enhancement. The aim of the study was to investigate the relationship between tumor blood flow, measured by ASL, and intraoperative fluorescent glow of gliomas of different grades. Materials and methods: Tumoral blood flow was assessed in 75 patients by pCASL (pseudo-continuous arterial spin labeling) within 1 week prior to surgery. In all cases of tumor removal, 5-ALA had been administered preoperatively. Maximum values of tumoral blood flow (TBF max) were measured, and normalized tumor blood flow (nTBF) was calculated. Results: A total of 76% of patients had significant contrast enhancement, while 24% were non-enhancing. The histopathology revealed 17 WHO grade II gliomas, 12 WHO grade III gliomas and 46 glioblastomas. Overall, there was a relationship between the degree of intraoperative tumor fluorescence and ASL-TBF (Rs = 0.28, p = 0.02 or the TBF; Rs = 0.34, p = 0.003 for nTBF). Non-enhancing gliomas were fluorescent in 9/18 patients, with nTBF in fluorescent gliomas being 54.58 ± 32.34 mL/100 mg/s and in non-fluorescent gliomas being 52.99 ± 53.61 mL/100 g/s (p > 0.05). Enhancing gliomas were fluorescent in 53/57 patients, with nTBF being 170.17 ± 107.65 mL/100 g/s in fluorescent and 165.52 ± 141.71 in non-fluorescent gliomas (p > 0.05). Conclusion: Tumoral blood flow levels measured by non-contrast ASL perfusion method predict the fluorescence by 5-ALA; however, the additional value beyond contrast enhancement is not clear. ASL is, however, useful in cases with contraindication to contrast.