Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Meningioma firmness is a critical factor that influences ease of resection and risk, notably when operating on tumors intimate with neurovascular structures such as the mesial sphenoid wing. This study develops a predictive tool using preoperative magnetic resonance imaging (MRI) characteristics to determine meningioma consistency. 101 patients with intracranial meningioma (50 soft/51 firm) were included. MRI characteristics of 38 tumors (19 soft/19 firm) were retrospectively reviewed to identify preoperative imaging features that were then correlated with intraoperative description of the tumor as either "soft and/or suckable" or "firm and/or fibrous". Criteria were developed to predict consistency and then blindly applied to the remaining 63 meningiomas (31 soft/32 firm). The overall sensitivities for detecting soft and firm consistency were 90% and 56%, respectively (95% CI = 73-97% and 38-73%; P < 0.001). Compared to gray matter, meningiomas that were T2 hypointense were almost always firm. Soft meningiomas were hyperintense on T2 and hypointense on T1. Soft meningiomas were slightly larger and less likely to be associated with edema. There was a slight preponderance of firm meningiomas in the infratentorial compartment. Grade of meningioma was not predictive. Contrast enhancement, diffusion restriction, changes in overlying bone, intratumoral cysts, and angiographic features were not predictable. This tool using T1 and T2 series predicts meningioma consistency. Such knowledge should assist the surgeon in preoperative planning and counseling.

SUMMARY: Digital subtraction myelography is a valuable diagnostic technique to detect the exact location of CSF leaks in the spine to facilitate appropriate diagnosis and treatment of spontaneous spinal CSF leaks. Digital subtraction myelography is an excellent diagnostic tool for assessment of various types of CSF leaks, and lateral decubitus digital subtraction myelography is increasingly being used to diagnose CSF-venous fistulas. Lateral decubitus digital subtraction myelography differs from typical CT and fluoroscopy-guided myelograms in many ways, including equipment, supplies, and injection and image-acquisition techniques. Operators should be familiar with techniques, common pitfalls, and artifacts to improve diagnostic yield and prevent nondiagnostic examinations.

BACKGROUND AND PURPOSE: Spinal dural arteriovenous fistulas are commonly missed on imaging or misdiagnosed as inflammatory or neoplastic processes. We reviewed a consecutive series of spinal dural arteriovenous fistulas referred to our institution that were missed or misdiagnosed on initial imaging and studied the clinical consequences of missing or misdiagnosing the lesion. MATERIALS AND METHODS: We reviewed spinal dural arteriovenous fistulas diagnosed at our institution between January 1, 2000, and November 1, 2014. A lesion was defined as “misdiagnosed” if initial MR imaging or CT myelography demonstrated characteristic imaging features of spinal dural arteriovenous fistula but the patient was clinically or radiologically misdiagnosed. Outcomes included length of delay of diagnosis, increased disability (increase in mRS or Aminoff motor disability of ≥1 point) between initial imaging evaluation and diagnosis date, and posttreatment disability. RESULTS: Fifty-three consecutive spinal dural arteriovenous fistulas that were initially misdiagnosed despite having characteristic imaging findings on MR imaging or CT myelography were included in our study. Eight patients (18.9%) underwent spinal angiography before referral, which was interpreted as having negative findings but was either incomplete (6 cases) or retrospectively demonstrated the spinal dural arteriovenous fistulas (2 cases). The median time of delayed diagnosis was 6 months (interquartile range, 2–14 months). Fifty-one patients (96.2%) had increased disability between the initial study, which demonstrated features of a spinal dural arteriovenous fistula, and diagnosis. Thirty-two patients (60.4%) developed a new requirement for a walker or wheelchair. Following treatment, 21 patients (41.2%) had an improvement of 1 point on the mRS or Aminoff motor disability scale. CONCLUSIONS: Delayed diagnosis of spinal dural arteriovenous fistula with characteristic imaging features results in high rates of additional disability that are often irreversible despite surgical or endovascular treatment of the fistula.