Gopi Kota

Adult Renal Cystic Disease: A Genetic, Biological, and Developmental Primer

Renal cystic diseases in adults are a heterogeneous group of disorders characterized by the presence of multiple cysts in the kidneys. These diseases may be categorized as hereditary, acquired, or developmental on the basis of their pathogenesis. Hereditary conditions include autosomal dominant polycystic kidney disease, medullary cystic kidney disease, von Hippel-Lindau disease, and tuberous sclerosis. Acquired conditions include cystic kidney disease, which develops in patients with end-stage renal disease. Developmental cystic diseases of the adult kidney include localized renal cystic disease, multicystic dysplastic kidney, and medullary sponge kidney. In recent years, many molecular and cellular mechanisms involved in the pathogenesis of renal cystic diseases have been identified. Hereditary renal cystic diseases are characterized by genetic mutations that lead to defects in the structure and function of the primary cilia of renal tubular epithelial cells, abnormal proliferation of tubular epithelium, and increased fluid secretion, all of which ultimately result in the development of renal cysts. A better understanding of these pathophysiologic mechanisms is now providing the basis for the development of more targeted therapeutic drugs for some of these disorders. Cross-sectional imaging provides useful information for diagnosis, surveillance, prognostication, and evaluation of treatment response in renal cystic diseases.

Automated white matter total lesion volume segmentation in diabetes.

BACKGROUND AND PURPOSE: WM lesion segmentation is often performed with the use of subjective rating scales because manual methods are laborious and tedious; however, automated methods are now available. We compared the performance of total lesion volume grading computed by use of an automated WM lesion segmentation algorithm with that of subjective rating scales and expert manual segmentation in a cohort of subjects with type 2 diabetes. MATERIALS AND METHODS: Structural T1 and FLAIR MR imaging data from 50 subjects with diabetes (age, 67.7 ± 7.2 years) and 50 nondiabetic sibling pairs (age, 67.5 ± 9.4 years) were evaluated in an institutional review board–approved study. WM lesion segmentation maps and total lesion volume were generated for each subject by means of the Statistical Parametric Mapping (SPM8) Lesion Segmentation Toolbox. Subjective WM lesion grade was determined by means of a 0–9 rating scale by 2 readers. Ground-truth total lesion volume was determined by means of manual segmentation by experienced readers. Correlation analyses compared manual segmentation total lesion volume with automated and subjective evaluation methods. RESULTS: Correlation between average lesion segmentation and ground-truth total lesion volume was 0.84. Maximum correlation between the Lesion Segmentation Toolbox and ground-truth total lesion volume (ρ = 0.87) occurred at the segmentation threshold of k = 0.25, whereas maximum correlation between subjective lesion segmentation and the Lesion Segmentation Toolbox (ρ = 0.73) occurred at k = 0.15. The difference between the 2 correlation estimates with ground-truth was not statistically significant. The lower segmentation threshold (0.15 versus 0.25) suggests that subjective raters overestimate WM lesion burden. CONCLUSIONS: We validate the Lesion Segmentation Toolbox for determining total lesion volume in diabetes-enriched populations and compare it with a common subjective WM lesion rating scale. The Lesion Segmentation Toolbox is a readily available substitute for subjective WM lesion scoring in studies of diabetes and other populations with changes of leukoaraiosis.

The sea anchor technique: a novel method to aid in stent-assisted embolization of giant cerebral aneurysms

Endovascular navigation past some large or giant intracranial aneurysms for the purpose of stent deployment can be difficult. Some of these lesions have a morphology which compels the operator to navigate through the aneurysm dome in order to gain distal access, a step which requires straightening of the delivery microcatheter before a stent can be deployed. In most patients this can be achieved by simply retracting the microcatheter and reducing the loop within the aneurysm. However, in certain patients the acute angle formed between aneurysm inflow and outflow tracts as well as the dynamics of tension within the microcatheter act together to prevent this from happening. Instead of retracting and straightening across the aneurysm neck, the microcatheter withdraws leaving the intra-aneurysm loop intact. This challenge can thwart attempts at stent placement and subsequent embolization. The authors describe a simple and safe technique to circumvent this problem, a way of stabilizing the distal tip of the microcatheter which they term the ‘sea anchor’.

PET/CT illustration of metastatic breast cancer to the left mandibular foramen.

Mental nerve neuropathy (numb chin/lip syndrome) is a sensory neuropathy presenting with numbness in the distribution of the inferior alveolar nerve/mental nerve (chin and lower lip). This is typically unilateral and can be secondary to dental disease or malignancy. When caused by malignancy, these symptoms can be either an initial presentation of an unsuspected tumor or progressive metastatic disease, both of which would indicate poor prognosis. We describe a 48-year-old female patient with a history of breast cancer who presented with left chin numbness and manifested a metastatic lesion involving the left mandibular foramen on PET/CT and subsequent MRI.

Unilateral diffusely increased muscle uptake of F-18 FDG in a patient with hemiparesis due to stroke.

Although normal muscles accumulate less F-18 fluorodeoxyglucose (FDG) under normoglycemic conditions, FDG muscle uptake is frequently encountered on PET scans. However, diffusely elevated unilateral muscle uptake is not frequently seen. In this report, we demonstrate a case of unilateral muscle uptake in a patient with a remote history of stroke, possibly explained by increased spasticity, a shift toward fast twitch (type II) muscle fibers, and inflammatory changes that are all seen post–upper motor neuron injury. Thus, FDG PET may serve as a functional biomarker of the extent of upper motor neuron injury after stroke.

Somatostatin receptor molecular imaging for metastatic intracranial hemangiopericytoma.

Intracranial hemangiopericytomas (HPCs) are rare tumors that closely mimic meningiomas. However, in contrast to meningiomas, HPCs have a relatively high incidence of local recurrence and distant metastases, manifesting the need for sensitive noninvasive methods of detection that efficiently image the entire body. We present a rare case of a right optic nerve sheath HPC in which we identified a previously unknown distant metastasis in the thoracic spine on an 111In-pentetreotide scan. We detail the radiologic characteristics seen with somatostatin receptor imaging, FDG PET, and MRI and discuss how to exploit these findings to detect recurrence and metastatic disease in HPC.

Evolution of a ureteric stone from the renal pelvis to the ureter on skeletal scintigraphy with CT correlation.

Because bone-seeking radiopharmaceuticals are excreted into the urine by the kidneys, normal kidneys and bladder are well visualized on skeletal scintigrams leading to incidental detection of urinary tract abnormalities in up to 15% of bone scans. Although the findings pertaining to the urinary tract on skeletal scintigraphy are seldom suggestive of a definitive diagnosis, they are highly specific for renal disease, with fewer than 2% false-positive studies reported. In the presented case, we demonstrate the evolution of a ureteric stone from the renal pelvis into the ureter on sequential skeletal scintigraphy with CT correlation.

Targeting angiogenesis in an age of personalized medicine.

Commentary to: A fusion protein with the receptor binding domain of vascular endothelial growth factor-A (VEGF-A) is an antagonist of angiogenesis in cancer treatment: Simultaneous blocking of VEGF receptor-1 and 2 Feng-Jen Tseng, Yu-Cheng Chen, Yu-Ling Lin, Nu-Man Tsai, Ru-Ping Lee, Yo-Shong Chung, Chia-Hung Chen, Yen-Ku Liu, Yu-Shan Huang, Chia-Hsiang Hwang, Yiu-Kay Lai and Kuang-Wen Liao