A non-cardiac applications of T1-mapping

T1-mapping has proven to be a valuable tool in cardiac imaging. While mainly used in cardiac MRI, it is investigated for usage and application of T1-mapping to imaging of other organs and systems, including abdominal imaging, musculoskeletal imaging or neuroradiology, resulting in potential new prospects for medical imaging. T1-mapping provides numerical data on an inherent, physical property of imaged tissue – enabling quantitative and comparative assessment of tissue characterization f.ex. fibrosis, amyloid contents, fatty transformation, myelinization or contrast enhancement as well as lesion characterization. Reports of application of T1-mapping in assessment of liver, kidney or pancreas fibrosis create perspectives of reducing the number of invasive diagnostic procedures, such as biopsies, as well as monitoring treatment response or disease progression. Furthermore T1-mapping can potentially replace MR elastography in assessment of liver fibrosis or used in thyroid fibrosis to define degree of destruction in AIT or other thyroid diseases. In neuroradiology T1-mapping is promising in the spine imaging, enabling better characterization of spinal cord lesions also has a potential to evaluate effectiveness of conservative or operative treatment. There are also successful reports of employing T1-mapping in orbital imaging, such as in predicting steroid resistant diplopia in Graves’ disease or in evaluation of diabetic cataracts. In musculoskeletal imaging, T1-relaxation could be a possible biomarker of bone quality that could play a role in osteoporotic fracture risk assessment. In conclusion, T1-mapping shows promise as a quantitative method complementary to standard MR imaging beyond cardiac MRI, and needs further research and validation efforts to establish its place in standard diagnostic protocols.

Optimal estimation of snow and ice surface parameters from imaging spectroscopy measurements

<p>Snow and ice melt processes are key variables in Earth energy-balance and hydrological modeling. Their quantification facilitates predictions of meltwater runoff and distribution and availability of fresh water. Furthermore, they are indicators of climate change and control the balance of the Earth's ice sheets. These processes decrease the surface reflectance with unique spectral patterns due to the accumulation of liquid water and light absorbing particles (LAP), making imaging spectroscopy a powerful tool to measure and map this phenomenon. Here we present a new method to retrieve snow grain size, liquid water fraction, and LAP mass mixing ratio from airborne and space borne imaging spectroscopy acquisitions. This methodology is based on a simultaneous retrieval of atmospheric and surface parameters using optimal estimation (OE), a retrieval technique which leverages prior knowledge and measurement noise in the inversion and also produces uncertainty estimates. We exploit statistical relationships between surface reflectance spectra and snow and ice properties to estimate their most probable quantities given the reflectance. To test this new algorithm we conducted a sensitivity analysis based on simulated top-of-atmosphere radiance spectra using the upcoming EnMAP orbital imaging spectroscopy mission, demonstrating an accurate estimation performance of snow and ice surface properties. An additional validation experiment using in-situ measurements of glacier algae mass mixing ratio and surface reflectance from the Greenland Ice Sheet yields promising results. Finally, we evaluated the retrieval capacity for all snow and ice properties with an AVIRIS-NG acquisition from the Greenland Ice Sheet demonstrating this approach’s potential and suitability for upcoming orbital imaging spectroscopy missions.</p>

Orbital Hydatid Cyst: An Interventional Case Series

Purpose: To find out the demographics, presentation, and outcome of surgical treatment in patients of orbital hydatid cyst. Study Design: Interventional case series. Place and Duration of Study: Khyber Teaching Hospital Peshawar, Pakistan from 2009 to 2019. Methods: This study included 11 patients with orbital hydatid cyst who presented in Khyber Teaching Hospital, Peshawar. Detailed history, ocular examination and Orbital imaging (Ophthalmic B-Scan, CT scan and/or MRI) was performed. The patients underwent Orbitotomy, cyst extirpated and sent for histopathology. Albendazole was given to the patients for 12 weeks after surgery. The preoperative and postoperative data until last follow-up was analyzed. Results: Male to Female ratio was 5:6 and the mean age of the patients was 18.17 ± 17.4 years. Mean amount of proptosis was 26.27 ± 2.05mm and visual acuity was 0.23 ± 0.33 decimal in the affected eye at presentation. Eight patients (72.8%) had Relative Afferent Pupillary Defect with swollen discs. After imaging studies, presumptive diagnosis of hydatid cyst was made. Histopathology confirmed the diagnosis of hydatid cyst in all cases. Mean proptosis at the last follow up improved to 19.04 ± 1.45mm (P value = 0.00) and visual acuity to 0.47 ± 0.22 decimals (P value = 0.048). Only one patient (9.1%) had an associated hydatid cyst in the lung. There was no recurrence until last follow-up. Conclusion: Hydatid cyst should be considered in differential diagnosis of proptosis in patients under 20. Surgical excision followed by a course of oral Albendazole is effective for the treatment of orbital hydatid cyst. Key Words: Orbital hydatid cyst, Proptosis, Orbitotomy.

Primary Malignant Orbital Tumors

Objective Primary orbital malignancy is rare. Awareness of the characteristic clinical and imaging features is imperative for timely identification and management. Surgery remains an important diagnostic and treatment modality for primary orbital malignancy, but determining the optimal surgical approach can be challenging. The purpose of this article is to explore recent advances in the diagnosis, management, and surgical approaches for primary orbital malignancies. Design In this review, the clinical presentation, imaging features, and medical and surgical management of primary orbital malignancies with representative cases will be discussed. Setting Outpatient and inpatient hospital settings. Participants Patients with diagnosed primary orbital malignancies. Main Outcome Measures Descriptive outcomes. Results Advancements in orbital imaging, microsurgical techniques, and multimodal therapy have improved the diagnosis and management of primary orbital malignancies. Special considerations for biopsy or resection are made based on the tumor's location, characteristics, nearby orbital structures, and goals of surgery. Minimally invasive techniques are supplanting traditional approaches to orbital surgery with less morbidity. Conclusions Advances in imaging technologies and surgical techniques have facilitated the diagnosis and management of primary orbital malignancies. Evolution toward less invasive orbital surgery with focus on preservation and restoration of function is underway.

Masses of the Lacrimal Gland: Evaluation and Treatment

Lacrimal gland lesions account for approximately 9 to 10% of all biopsied orbital masses. Potential causes include nongranulomatous and granulomatous inflammation, autoimmune disease, lymphoproliferative disorders, benign epithelial proliferation, malignant neoplasia, and metastatic disease. Inflammatory lesions and lymphoproliferative disorders are the most common and may be unilateral or bilateral; they may also be localized to the orbit or associated with systemic disease. Both benign and malignant epithelial lacrimal gland masses tend to be unilateral and involve the orbital lobe, but a more rapid onset of symptoms and periorbital pain strongly suggest malignant disease. On orbital imaging, both inflammatory and lymphoproliferative lesions conform to the globe and surrounding structures, without changes in adjacent bone, whereas epithelial lacrimal gland masses often show scalloping of the lacrimal gland fossa. Malignant epithelial lacrimal gland tumors can also have radiographic evidence of bony invasion and destruction. Masses of the lacrimal gland may be due to a broad range of pathologies, and a good working knowledge of common clinical characteristics and radiographic imaging findings is essential for diagnosis and treatment. All patients with inflammatory, lymphoproliferative, and epithelial neoplastic lesions involving the lacrimal gland require long-term surveillance for disease recurrence and progression.