Dr. KID: Direct Remeshing and K-Set Isometric Decomposition for Scalable Physicalization of Organic Shapes.

Dr. KID is an algorithm that uses isometric decomposition for the physicalization of potato-shaped organic models in a puzzle fashion. The algorithm begins with creating a simple, regular triangular surface mesh of organic shapes, followed by iterative K-means clustering and remeshing. For clustering, we need similarity between triangles (segments) which is defined as a distance function. The distance function maps each triangle's shape to a single point in the virtual 3D space. Thus, the distance between the triangles indicates their degree of dissimilarity. K-means clustering uses this distance and sorts segments into k classes. After this, remeshing is applied to minimize the distance between triangles within the same cluster by making their shapes identical. Clustering and remeshing are repeated until the distance between triangles in the same cluster reaches an acceptable threshold. We adopt a curvature-aware strategy to determine the surface thickness and finalize puzzle pieces for 3D printing. Identical hinges and holes are created for assembling the puzzle components. For smoother outcomes, we use triangle subdivision along with curvature-aware clustering, generating curved triangular patches for 3D printing. Our algorithm was evaluated using various models, and the 3D-printed results were analyzed. Findings indicate that our algorithm performs reliably on target organic shapes with minimal loss of input geometry.

The tendency of segmental distribution of hepatic metastasis according to couinaud classification: a comparison of portal versus systemic route of metastatis due to primary colorectal and breast tumors.

Objective: The liver is the commonest site of metastatic disease for patients with colorectal cancer (CRC), with at least 25% of patients developing liver metastasis (LM) during their illness. About 50% of patients diagnosed with metastatic breast cancer develop LM, and 5-12% of these patients develop LM as the main site of breast cancer recurrence. This study aims to determine the frequency of segmental distribution of LM seeding from portal versus systemic routes of dissemination due to primary CRC and breast carcinoma, respectively. Material and methods: This retrospective study was conducted in a tertiary care teaching hospital in Pakistan. Ethical approval was taken from the institutional review board. A total of 587 patients were included in the study with 297 CRC patients with LM and 300 breast carcinoma patients with LM. Segment I involvement was excluded from the calculation because of the dual blood supply. Patients' detailed demographics and other information were collected on a predesigned proforma. The authors evaluated axial and multiplanar reformatted computed tomography images for LM and CRC metastasis. Data analysis was done using SPSS version 25. P value less than or equal to 0.05 was considered statistically significant. Results: A study population of 587 patients was employed that comprised 287 CRC and 300 breast carcinoma patients. There were 179 (30.5%) male and 408 (69.5%) female patients. The mean age of patients was 54.9±13.3. The study revealed that 204 (34.8%) CRC patients showed right lobe (V, VI, VII, VIII) and 83 (14.1%) CRC patients showed left lobe involvement of metastasis while 192 (32.7%) breast carcinoma patients showed right lobe involvement and 108 (18.4%) breast carcinoma patients showed left lobe involvement in metastasis (P=0.02). We also found 40 (6.8%) colorectal and 55 (9.4%) breast carcinoma patients showed left lateral segment (II, III) involvement. Medial segment involvement (IV) was seen in 43 (7.3%) CRC patients and 53 (9%) breast carcinoma patients (P=0.03). Conclusion: The right hepatic lobe is the predominant site of metastasis independent of the portal or systemic route of dissemination in primary carcinoma. Moreover, in left lobe metastasis medial segment (IV) is more affected in CRC while the lateral segment (II, III) is more affected in breast carcinoma.

Surface Remeshing: A Systematic Literature Review of Methods and Research Directions.

Triangle meshes are used in many important shape-related applications including geometric modeling, animation production, system simulation, and visualization. However, these meshes are typically generated in raw form with several defects and poor-quality elements, obstructing them from practical application. Over the past decades, different surface remeshing techniques have been presented to improve these poor-quality meshes prior to the downstream utilization. A typical surface remeshing algorithm converts an input mesh into a higher quality mesh with consideration of given quality requirements as well as an acceptable approximation to the input mesh. In recent years, surface remeshing has gained significant attention from researchers and engineers, and several remeshing algorithms have been proposed. However, there has been no survey article on remeshing methods in general with a defined search strategy and article selection mechanism covering the recent approaches in surface remeshing domain with a good connection to classical approaches. In this article, we present a survey on surface remeshing techniques, classifying all collected articles in different categories and analyzing specific methods with their advantages, disadvantages, and possible future improvements. Following the systematic literature review methodology, we define step-by-step guidelines throughout the review process, including search strategy, literature inclusion/exclusion criteria, article quality assessment, and data extraction. With the aim of literature collection and classification based on data extraction, we summarized collected articles, considering the key remeshing objectives, the way the mesh quality is defined and improved, and the way their techniques are compared with other previous methods. Remeshing objectives are described by angle range control, feature preservation, error control, valence optimization, and remeshing compatibility. The metrics used in the literature for the evaluation of surface remeshing algorithms are discussed. Meshing techniques are compared with other related methods via a comprehensive table with indices of the method name, the remeshing challenge met and solved, the category the method belongs to, and the year of publication. We expect this survey to be a practical reference for surface remeshing in terms of literature classification, method analysis, and future prospects.

Interobserver Reliability of the RENAL Nephrometry Scoring System: Experience From a Developing Nation.

Introduction The RENAL (radius, exophytic/endophytic properties, nearness of tumor to the collecting system or sinus in millimeters, anterior/posterior, location relative to polar lines) nephrometry score (RENAL-NS) has been described as a structured and quantifiable method to describe a renal tumor's relevant anatomic features as they relate to the complexity of the lesion. We aim to evaluate a tumor's RENAL-NS and to assess the reproducibility of the score among different observers. Methods This retrospective study included 49 patients diagnosed with renal cell carcinoma (RCC) who had complete computed tomography (CT) data, RENAL-NS, and histopathology results. All patients underwent renal surgery/intervention at our center between January 2008 and December 2018. The radius of the lesion, exophytic/endophytic properties, nearness to the collecting system, anterior or posterior description, and location relative to the polar lines was used to calculate the score. Tumor complexity was graded as low, intermediate, or high. Two body imaging radiologists evaluated the data independently. Results Interobserver agreement for each of the RENAL-NS parameters, respectively, and overall complexity was calculated. The total agreement was 82%, 51%, 84%, 69%, 73%, and 90%, corresponding to Kappa values of 0.72, 0.33, 0.44, 0.49, 0.58, and 0.83, respectively. The radius, nearness to the collecting system, and total complexity showed the best agreement. Exophytic properties of the lesion showed the least agreement. For cases that were discordant in terms of the final score, no major implications in surgical planning were observed. Conclusion The results of this study show that the RENAL-NS is a useful tool to assess the anatomical features of renal tumors and it is easily reproducible, even for less experienced radiologists in a developing nation.

Surgical and oncological implications of aberrant arterial anatomy in patients undergoing pancreatoduodenectomy.

Whipple's pancreatoduodenectomy is a complex surgical procedure and any aberrant arterial anatomy may have serious surgical implications. The objective of our study was to analyse the frequency of aberrant hepatic artery and compare the outcomes in patients with normal anatomy. Clinical data and computed tomography scans of 45 consecutive patients who underwent Whipple's procedure from 2007 to 2016 were reviewed. Group 'A' included patients with aberrant hepatic artery while group 'B' with normal anatomy. Aberrant hepatic artery was present in 11 (24%) patients and type V was the most common variant (n=5, 45%). Morbidity rate in group A was 82% and group B was 62% (p= 0.288), while 30-day mortality rate was 18% and 9% respectively (p=0.582). There was no difference in the oncological clearance in both the groups. Aberrant hepatic artery does not seem to influence the morbidity, mortality and tumour resection margins in patients undergoing Whipple's procedure.

Angiography and Therapeutic Embolisation of Bleeding Aberrant Iliac Artery Branches.

A 78-year female presented with the complain of per rectal fresh bleeding for 4 days. She was known to have diabetes and hypertension, 3 weeks back. She had an episode of left middle cerebral artery (MCA) stroke. After stroke, she suffered from upper limb weakness and aphasia. At the time of presentation, her vitals showed blood pressure of 118/52 mmHg, O2 saturation of 98%, temperature: 37°C, respiratory rate (RR) of 20/min, and heart rate (HR) of 90 bpm. After achieving hemodynamic stability, she was transferred to radiology department. Her presenting complain of active rectal bleeding was managed by interventional radiologist using angiographic embolisation. In this patient, it was found pooling of blood in a retrograde fashion in the sigmoid colon. Bleeding was initially believed to be coming from sigmoid arteries seen on images of CT scan and colonoscopy. However, arteriography showed that source of bleeding was from middle and inferior rectal arteries that originated from left internal iliac artery. The intervention radiology (IR) team had to put in extensive effort to locate and perform therapeutic embolisation.

Bilateral Pulmonary Artery Mycotic Aneurysms in a Female with Infective Endocarditis.

We present a case of a young female who had large bilateral pulmonary artery aneurysms and was found to have infective endocarditis on echocardiography. Endovascular treatment was sought; however, was not possible due to severe sepsis and other associated complications. Subsequent serial imaging revealed the rapid enlargement of one of the aneurysms and possible rupture which proved to be fatal. Although pulmonary artery aneurysms are a rare vascular anomaly, they are seen in a wide variety of conditions, such as congenital heart disease, infection, trauma, pulmonary hypertension, cystic medial necrosis, and generalized vasculitis. This case highlights the consequences of mycotic aneurysms and emphasizes the importance of prompt diagnosis. Early angioembolization and/or surgical repair is often essential to avoid death from rupture of the aneurysm.

Cholecystocolonic Fistula.

Cholecystocolonic fistula (CCF) is a rare complication of gallstone disease with a variable clinical presentation. It is difficult to diagnose CCF pre-operatively despite modern diagnostic and imaging modalities as they are often asymptomatic or incidentally discovered, often peri-operatively. However, management of this uncommon yet important finding is not very well described in the literature. The most common fistula is the cholecystoduodenal fistula, followed by the cholecystocolonic fistula; the cholecystogastric fistula is reportedly the least commonly reported. We report our experience with three cases of cholecystocolonic fistula discovered on imaging which were subsequently confirmed through surgery.

Torsion of Wandering Spleen with Infarction.

Wandering spleen is a rare entity that results from the absence or maldevelopment of the ligaments that support the spleen in its normal location. As a result, the spleen is hypermobile and may be predisposed to hilar torsion and subsequent infarction, making it a potentially fatal abdominal emergency. We present a case of a 36-year-old Afghan female who presented with an acute abdomen, and was radiologically and surgically confirmed to have a wandering spleen with torsion and complete infarction. Knowledge of this condition and its radiological findings can play a crucial role in making a correct and timely diagnosis.

Molecular Surface Remeshing with Local Region Refinement.

Molecular surface mesh generation is a prerequisite for using the boundary element method (BEM) and finite element method (FEM) in implicit-solvent modeling. Molecular surface meshes typically have small angles, redundant vertices, and low-quality elements. In the implicit-solvent modeling of biomolecular systems it is usually required to improve the mesh quality and eliminate low-quality elements. Existing methods often fail to efficiently remove low-quality elements, especially in complex molecular meshes. In this paper, we propose a mesh refinement method that smooths the meshes, eliminates invalid regions in a cut-and-fill strategy, and improves the minimal angle. We compared our method with four different state-of-the-art methods and found that our method showed a significant improvement over state-of-the-art methods in minimal angle, aspect ratio, and other meshing quality measurements. In addition, our method showed satisfactory results in terms of the ratio of regular vertices and the preservation of area and volume.

Institutional Review of Hemorrhagic Pelvic Emergencies Effectively Managed with Percutaneous Arterial Embolization.

OBJECTIVE: Our aim was to review the results of pelvic arterial embolization (PAE) performed in the interventional radiology suite. METHOD: The data of all patients in whom pelvic angioembolization was performed was collected from July 2011 to June 2017. Procedures were performed by an experienced interventional radiologist. The clinical and laboratory data, as well as the outcome data, were obtained from the medical records of our hospital. The following parameters were collected for each patient, including the age, gender, presenting symptoms, site of bleeding, catheters used for embolization, material used for embolization, previous computed tomography (CT) scan and/or focused assessment with sonography for trauma (FAST) ultrasound, average hemoglobin before the procedure, and patient clinical status on discharge. RESULT: A total of 37 patients underwent pelvic angiography for acute hemorrhage at our institution. They had contrast blush, active extravasation, or abnormal vascularity from the branches of the internal iliac artery and underwent therapeutic transcatheter embolization. A total of 29 patients (78.3%) were male and 8 (21.7%) were female. The average age was 30.0 years (range: 6-90 year). Of these, 16 patients (43.2%) presented with road traffic accidents (RTAs), six with gunshot injuries (16.2%), six with iatrogenic injuries (16.2%), four with a history of a fall (10.8%), two with bomb blast injuries (5.4%), one with a history of a glass injury (2.7%), one had a history of a roof falling on her during an earthquake, and one patient had a pelvic pseudoaneurysm secondary to an abscess. The type of embolic material used for embolization included coils in 16 patients, polyvinyl alcohol (PVA) particles were used in eight patients, both PVA particles and coils were used in 11 patients, and glue was used in one patient. All were successfully embolized. Thirty-four were discharged while three patients expired during the course of hospital stay due to other coexisting morbidities. CONCLUSION: The management of pelvic injuries has always been a topic of debate, with multiple methods reported to date but growing evidence supports the use of pelvic arterial embolization in hemorrhagic pelvic injuries. The formulation of a standardized protocol is the need of the day.

Frontiers in biomolecular mesh generation and molecular visualization systems.

With the development of biomolecular modeling and simulation, especially implicit solvent modeling, higher requirements are set for the stability, efficiency and mesh quality of molecular mesh generation software. In this review, we summarize the recent works in biomolecular mesh generation and molecular visualization. First, we introduce various definitions of molecular surface and corresponding meshing software. Second, as the mesh quality significantly influences biomolecular simulation, we investigate some remeshing methods in the fields of computer graphics and molecular modeling. Then, we show the application of biomolecular mesh in the boundary element method (BEM) and the finite element method (FEM). Finally, to conveniently visualize the numerical results based on the mesh, we present two types of molecular visualization systems.

Accuracy and reliability of tablet computer as an imaging console for detection of radiological signs of acute appendicitis using PACS workstation as reference standard.

PURPOSE: To ascertain the accuracy and reliability of tablet as an imaging console for detection of radiological signs of acute appendicitis [on focused appendiceal computed tomography (FACT)] using Picture Archiving and Communication System (PACS) workstation as reference standard. METHODS: From January, 2014 to June, 2015, 225 patients underwent FACT at our institution. These scans were blindly re-interpreted by an independent consultant radiologist, first on PACS workstation and, two weeks later, on tablet. Scans were interpreted for the presence of radiological signs of acute appendicitis. Accuracy of tablet was calculated using PACS as reference standard. Kappa (κ) statistics were calculated as a measure of reliability. RESULTS: Of 225 patients, 99 had radiological evidence of acute appendicitis on PACS workstation. Tablet was 100% accurate in detecting radiological signs of acute appendicitis. Appendicoliths, free fluid, lymphadenopathy, phlegmon/abscess, and perforation were identified on PACS in 90, 43, 39, 10, and 12 scans, respectively. There was excellent agreement between tablet and PACS for detection of appendicolith (к = 0.924), phlegmon/abscess (к = 0.904), free fluid (к = 0.863), lymphadenopathy (к = 0.879), and perforation (к = 0.904). CONCLUSIONS: Tablet computer, as an imaging console, was highly reliable and was as accurate as PACS workstation for the radiological diagnosis of acute appendicitis.

Role of early contrast enhanced CT scan in severity prediction of acute pancreatitis.

Severe pancreatitis occurs in approximately 15-25% of patients with acute pancreatitis. The objective of our study was to compare the CT Severity Index (CTSI) with a clinical score (BISAP score) to predict severity of acute pancreatitis. Forty-eight consecutive patients with acute pancreatitis who underwent contrast enhanced CT scan within 72 hours of presentation were included. Results of our study showed that both CTSI and BISAP score were reliable predictors of mortality (p value = 0.019 and <0.001 respectively) and need for mechanical ventilation (p value = .002 and .006 respectively). Positive predictive value of CTSI to predict recovery without intervention was 91.4% as compared to 78% for that of BISAP score. Receiver Operating Characteristics (ROC) Curves showed CT scan was superior to BISAP Score in predicting need of percutaneous or surgical intervention. Early CT scan may be utilized for prediction of clinical course of patients with acute pancreatitis.

Systematic approach to musculoskeletal benign tumors.

The radiologic workup of musculoskeletal tumors can be both cost-efficient and extremely helpful to the referring clinician if one proceeds in a thoughtful and logical manner. It should be remembered that plain films remain the most reliable imaging method for assessment of both biological activity and probable histologic diagnosis of an osseous lesion. Further investigations are of help to determine the extent of lesion and to help in staging. In order to do this, we have found it useful to include an assessment of 10 determinants in the description of a tumor. If these determinants are accurately described, the correct diagnosis or at least a limited differential diagnosis usually becomes obvious.

Eradication of advanced pelvic hydatid bone disease after limb salvage surgery - 5-year follow-up: a case report.

INTRODUCTION: Echinococcosis is produced by the larval stage of Echinococcus granulosus; it is a parasitic disease which is seen rarely in humans and has adverse outcomes. We report a case of advanced pelvic hydatid bone disease with successful limb salvage surgery. Our patient had a 5-year follow-up without recurrence which is a rarity as per the literature. Early diagnosis and prompt medical therapy are necessary for effective management whereas delayed diagnosis is always fraught with the risk of recurrence and sepsis. CASE PRESENTATION: In 2009, a 30-year-old woman, native of Karachi (Sindhi ethnicity), presented at our clinic with history of a pathological fracture 11 years earlier. Her fracture was initially misdiagnosed and fixed. Subsequently she had persistent disease that progressed with time. Following this she underwent multiple surgeries and the diagnosis of hydatid disease was made but despite multiple debridements and medical therapy she was not cured and finally she was offered a hemipelvectomy (limb sacrifice). On presentation to our hospital she was counseled regarding options of hemipelvectomy versus a limb salvage form of modified internal hemipelvectomy and wide margin resection. She opted for limb salvage. She underwent internal hemipelvectomy with wide margin resection of soft tissue and proximal femur along with postoperative albendazole therapy. She was able to walk again after a very long period. Currently she is 5-years postreconstructive surgery. She is infection free and ambulant without support. CONCLUSIONS: Hydatid bone disease is a rare entity in our part of the world but a careful history and thorough look at the initial images of our patient would have led to the suspicion of pathologic fracture and subsequent early diagnosis of this difficult problem. A second important learning point in this case was the lack of early referral to a center where this difficult problem could have been handled effectively. This could have minimized the physical, mental and financial stress to the patient and her family.

TESTICULAR LIPOMATOSIS IN COWDEN DISEASE.

Cowden disease is a genetic syndrome resulting in formation of multiple premalignant hamartomas in different parts of the body with classical radiological features. In this report a case of Testicular Lipomatosis as a result of Cowden disease resulting in primary infertility.

Utility of limited protocol magnetic resonance imaging lumbar spine for nerve root compression in a developing country, is it accurate and cost effective?

STUDY DESIGN: Cross sectional study. PURPOSE: To determine the accuracy of the screening magnetic resonance study of the lumbar spine in the diagnosis of nerve root compression in cases of low back pain as compared to the routine magnetic resonance imaging (MRI) study of the lumbar spine. OVERVIEW OF LITERATURE: No local study has been conducted for this purpose. In an international study, the reported sensitivity and specificity of screening MRI lumbar spine protocol in the detection of nerve root compression are 54% and 100% respectively. METHODS: Patients of both genders older than 20 years of age with low back pain of any duration or any severity who were referred to the radiology department of Aga Khan University Hospital for MRI of their lumbar spine were evaluated. Two sets of MRI imaging were recruited for each patient: one labeled as 'screening' and the other labeled as 'routine'. The findings of screening MRI were compared with the findings of the routine MRI study. RESULTS: A total of 109 patients fulfilling the inclusion criteria were included in this study. The diagnostic accuracy, specificity and sensitivity of the screening protocol in our study was 100%, 100% and 100%, respectively in comparison with the routine MRI lumbar spine study for the detection of nerve root compression. CONCLUSIONS: Our data proved that the MRI screening study is a highly accurate tool, and its findings are comparable to the routine study for the detection of nerve root compression especially in cases of lumbar spondylosis.

Percutaneous radiologic gastrostomy: results and complications.

BACKGROUND: Percutaneous endoscopic gastrostomy is usually difficult in patients with malignant involvement of oral cavity, pharynx and esophagus. Flouroscopic guided insertion of Gastrostomy catheter with Gastropexy have gained acceptance because it is easy and less time consuming as well as less invasive as compare to surgical procedure. This study was done to evaluate the safety and efficacy of percutaneous placement of gastrostomy with gastropexy using imaging guidance in patients with oropharyngeal and esophageal cancers. METHODS: Over five years, 105 patients were referred to our department for percutaneous radiologic gastrostomy. In five patients the procedure was not performed because of overlying viscera and high position of stomach. We performed 100 gastrostomies with gastropexy procedures using seldinger technique. RESULTS: Success rate for percutaneous radiologic gastrostomy was 100%. No major complication had occurred. There were 11 minor complications occurred including 4 stomal infection, 3 catheter obstruction, one peritonism and three were extensive pneumoperitoneum. Stomal infection and catheter obstruction were not related to procedure. So, our true minor complications were only 4 (4%) which is comparable to literature. CONCLUSION: Percutaneous radiologic gastrostomy is an effective and safe procedure for enteric access of nutrition in patients with oral, pharyngeal and esophageal cancer where percutaneous endoscopic gastrostomy is difficult.