Imaging Pitfalls Research Articles

US and MR Imaging of the Extensor Compartment of the Ankle

Injuries to the extensor compartment of the ankle are uncommon and often are overlooked or misinterpreted at clinical presentation. Ultrasonography (US) and magnetic resonance (MR) imaging play a critical role in the diagnosis and evaluation of these injuries. US is a dynamic, quick, cost-effective imaging method for assessing ankle extensor compartment injuries as an alternative or adjunct to MR imaging. MR imaging provides multiplanar cross-sectional delineation of regional anatomic structures and also can be used to assess the predisposing cause, estimate the extent of injury, and aid in preoperative planning for requisite surgical repair. The spectrum of pathologic conditions affecting the ankle extensor compartment ranges from tendinosis secondary to degenerative, inflammatory, or depositional disease to traumatic tendon or retinacular rupture and entrapment neuropathy. Major components of the ankle extensor compartment at risk for injury include the anterior tibial, extensor hallucis longus, and extensor digitorum longus tendons; the extensor retinacular mechanism; and the anterior tarsal tunnel. Familiarity with the normal anatomic appearance and pathologic features of the ankle extensor compartment at US and MR imaging as well as potential imaging pitfalls is critical for accurate injury evaluation.

“Cystic”‐appearing soft tissue masses: What is the role of anatomic, functional, and metabolic MR imaging techniques in their characterization?

Although conventional MR imaging with contrast-enhanced T1-weighted sequences is of paramount importance for evaluating soft tissue masses, noncontrast MR sequences have emerged that facilitate their characterization. In this article, the utility and pitfalls of conventional MR imaging with T1-weighted, fluid-sensitive, and contrast-enhanced sequences will be discussed, along with that of functional (diffusion weighted imaging) and metabolic (proton MR spectroscopy) non-contrast-enhanced techniques for the purpose of soft tissue mass characterization. In particular, we discuss the application of these techniques to differentiating neoplastic or inflammatory masses that have high fluid content from benign cysts, as this distinction is a common pitfall of conventional sequences.

Role of PET / CT in Management of Chest Tumors

ABSTRACT OBJECTIVE: to identify the role of PET-CT in management of chest tumors. PATIENTS AND METHODS: Whole body PET/CT study was performed on 32 patients of variable primary & secondary chest tumors who were under evaluation for primary or secondary chest tumors by recent CT, referred for staging before treatment and / or follow up after treatment. RESULTS: Our findings indicate that FDG PET/CT has an important impact on diagnosis & management of chest tumors , as it delineated the metabolic activity of the disease in 19 patients (59.4 %), outlined the metabolic activity of the tumoral residue in 6 patients (18.75%) , differentiated between tumoral residue & post irradiation pneumonitis in 1 patient (3.1%), followed up the therapeutic response in 4 patients (12.5 %), differentiated between residual mass & post therapeutic fibrosis in 1 patient (3.1%) and delineated the metabolic activity of the disease for preparing for BMT in 1 patient (3.1%) and so had an impact on the management of chest tumor patients. CONCLUSION: By recognizing the relevant radiologic and metabolic behavior of chest tumors, understanding the appropriateness of staging disease with the TNM classification system, and being familiar with potential imaging pitfalls, PET/CT can make an important contribution to diagnosis, treatment and outcome in chest tumor patients.

Brainstem Strokes in Children: An 11-Year Series From a Tertiary Pediatric Center

MethodsPotential clinical barriers to making a timely diagnosis of pediatric brainstem stroke and pitfalls of noninvasive vascular imaging are presented. MethodsAn institutional review board–approved institutional database query from 2001-2012 yielded 15 patients with brainstem strokes. Medical records were reviewed for symptoms, stroke severity using the Pediatric National Institutes of Health Stroke Scale, and outcomes using the Pediatric Stroke Outcome Measure. Magnetic resonance angiography was compared with digital subtraction angiography. ResultsThere were 10 boys and five girls; 9 months to 17 years of age (mean 7.83 years). Symptoms were headaches (eight); visual problems (eight), seizure-like activity (seven), motor deficits (six), and decreased level of consciousness in four. Time since last seen well was 12 hours to 5 days. Pediatric National Institutes of Health Stroke Scale was 1-34; <10 in eight; 3 in 1, 10-20 in two, and >20 in four. Strokes were pontine in 13/15 and involved >50% of the pons in six and <50% in seven; 2/15 had medullary strokes. Magnetic resonance angiography showed basilar artery occlusion in 8/13 patients and vertebral artery dissection in two. Digital subtraction angiography done within 9-36 hours of magnetic resonance angiography in 10/15 patients confirmed the basilar artery occlusion seen by magnetic resonance angiography and showed vertebral artery dissection in four patients. Patients were systemically anticoagulated without hemorrhagic complications. One patient died. Pediatric Stroke Outcome Measures at 2-36 months is 0-5.0/10 (mean 1.25). ConclusionsVague symptoms contributed to delays in diagnosis. Magnetic resonance angiography was equivalent to digital subtraction angiography for basilar artery occlusion but not for vertebral artery dissection. Even with basilar artery occlusion and high stroke scales, outcome was good when systemic anticoagulation was started promptly.

Patterns of Nonmasslike Enhancement at Screening Breast MR Imaging of High-Risk Premenopausal Women

Current U.S. recommendations for breast cancer screening of women with at least a 20%-25% lifetime risk of developing breast cancer include contrast material-enhanced magnetic resonance (MR) imaging of the breasts. The cancer detection rate in high-risk women undergoing screening MR imaging is approximately 10 times higher than that in normal-risk women undergoing screening mammography. Many of these high-risk women commence MR imaging screening while they are premenopausal, when the breasts are most influenced by cyclical hormonal changes. Healthy premenopausal breast tissue enhances in a cyclical and variable manner. This enhancement is described as background enhancement. Typically, enhancement of normal breast tissue occurs in a symmetric and diffuse pattern, and there is little diagnostic difficulty in classifying it as normal background parenchymal enhancement. However, sometimes the pattern is more focal, asymmetric, or regional. It may then be described as nonmasslike enhancement, an observation associated with both benign and malignant breast pathologic conditions. A review of the morphologic features and internal enhancement patterns in normal but nondiffuse background enhancement and abnormal nonmasslike enhancement in high-risk premenopausal women can help improve interpretive specificity and decrease false-positive interpretations. MR imaging pitfalls and interpretation strategies for localized background enhancement and pathologic nonmasslike enhancement in this high-risk population are highlighted. In evaluating nonmasslike enhancement, the use of the Breast Imaging Reporting and Data System (BI-RADS) lexicon to perform careful analysis of morphologic features, along with an understanding of the role and limitations of kinetic information, will help balance early breast cancer detection against false-positive interpretation.

Patterns and Signal Intensity Characteristics of Pelvic Recurrence of Rectal Cancer at MR Imaging

Magnetic resonance (MR) imaging is becoming the cross-sectional imaging modality of choice for follow-up of patients with previous rectal cancer to diagnose pelvic recurrence and plan for surgery. The authors conducted a retrospective review of MR imaging examinations performed at their institution for evaluation of local recurrence of rectal cancer in 42 patients. Twenty-six patients had undergone rectal anastomosis and 16 had undergone abdominoperineal resection. The mean interval between initial surgery and recurrence was 2.5 years. Recurrence sites were axial (involving the anastomosis) (n = 19); lateral (sidewall) (n = 6); anterior (prostate or seminal vesicle [n = 2], bladder [n = 4], ureter [n = 3], vagina or uterus [n = 5]); or posterior (presacral fascia [n = 11], sacrum [n = 2]). Other recurrence sites included the pelvic floor (n = 7), sciatic nerve (n = 2), obturator nerve (n = 1), perineum (n = 1), abdominal wall (n = 1), or adnexa (n = 1). Recurrence was confirmed at surgery or by evidence of tumor growth at follow-up imaging. Recurrence patterns, signal intensity characteristics, findings of unresectability, potential MR imaging pitfalls, and the role of MR imaging versus other modalities in evaluating recurrent rectal carcinoma are discussed. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg335115170/-/DC1.

Imaging patterns of liver uptakes on PET scan: pearls and pitfalls

PET imaging is becoming increasingly universal, and therefore increased liver uptake is frequently encountered. The purpose of this article is to describe and illustrate the various morphological patterns of increased metabolic activity within the liver with an emphasis on the diagnostic pitfalls and potential limitations. Knowing the pitfalls of PET imaging, correlation with clinical background and findings from other imaging modalities are all important in the correct interpretation of increased hepatic activity on PET imaging.

Unenhanced CT in the evaluation of renal/ureteric colic

Unenhanced CT of kidneys, ureters and bladder (CTKUB) is now the recommended imaging modality in the investigation of patients with acute renal or ureteric colic. This review aims to illustrate the normal urinary tract anatomy to assist imaging interpretation, outline the CTKUB imaging technique and image review at the Picture Archiving and Communication System workstation, discuss the pertinent imaging findings such as the direct signs, for example, soft tissue rim sign and comet tail sign, as well as secondary indirect signs such as pale kidney sign, nephromegaly, hydronephrosis, hydroureter and perinephric stranding or edema on the CTKUB for the diagnosis. Imaging pitfalls in the interpretation will be illustrated and discussed, for example in the presence of a ureteral stent and optimal image interpretation with wide windowing on CT. In addition, the discussion will also include the use of scout radiograph, the importance of detecting extraurinary pathology during CTKUB examination and explore Randall...

Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: a musculoskeletal division’s experience

To determine the accuracy of MR imaging for the evaluation of the subscapularis tendon as well as define imaging findings that will increase accuracy. Retrospective review of the MR and operative (OR) reports of 286 patients was conducted and reviewed for the presence/degree (partial (PT)/full-thickness (FT)) of tearing; only PT articular tears were included. The presence of a supraspinatus tear and time interval between surgery and MRI were also documented. All of the PT tears called on MRI were also reviewed to see if there was a statistically significant association between certain imaging characteristics and the presence of a tear in surgery. Statistical analysis included 95 % confidence intervals, Fisher’s exact, and exact Mann–Whitney tests. A total of 244 patients were included in the study with a total of 25 subscapularis tears, 16 PT and nine FT, and 219 intact tendons in arthroscopy; 20/25 tears and 200 intact sensitivity of 80%, specificity of 91%, accuracy of 90%, positive predictive value of 51%, and negative predictive value of 98 %. There was a significant association between the presence of a PT tear during arthroscopy and fluid-like signal within the tendon on more than one imaging plane (p<0.001) with an accuracy of 90%. This study reflects a musculoskeletal radiology section’s experience with the diagnosis of subscapularis tendon pathology, demonstrating that MRI could be used to accurately evaluate the subscapularis tendon. An understanding of certain imaging pitfalls and the presence of fluid-like signal on multiple imaging planes should increase the diagnostic accuracy of the radiologist evaluating the subscapularis tendon for the presence of a tear.

CT perfusion in acute stroke: Know the mimics, potential pitfalls, artifacts, and technical errors

The CT perfusion (CTP) imaging of brain has been established as a clinically useful tool in multimodality imaging of acute stroke. All abnormalities seen on perfusion CT are not specifically related to acute infarct. There are many neurologic diseases causing symptoms simulating cerebrovascular disease produce an alteration of brain perfusion and thus can result in perfusion CT abnormalities. There are many pitfalls and artifacts in acquiring the data, calculation of maps and choosing arterial input function. We analyze and classify all these aspects, to allow the technician and the radiologist to know exactly what to avoid and what to choose, and we indicate the way to improve the quality of examination. The knowledge of mimics and pitfalls in acute stroke imaging can be helpful in accurate interpretation of these examinations.

Carotid Artery Disease Imaging: A Home-Produced, Easily Made Phantom for Two- and Three-Dimensional Ultrasound Simulation

Background and Purpose —Ultrasound (US) plaque characterization has great potential with regard to maximizing the information traditionally gathered with spectral Doppler examination. It can directly visualize plaque and quantify better features such as surface morphology, geometry, volume, and echotexture via B-mode and the three-dimensional (3D) imaging mechanism. One of the major pitfalls of carotid imaging is the use of freehand manual manipulation. The application of angling, steering, as well as variability in the technical parameters, can increase the interobservation inconsistency. A limited number of commercial phantoms are available to teach this advanced technique but come at a high cost. We developed a home-produced phantom model to practice and teach carotid atherosclerotic disease imaging. We also investigated interobservation variability using two-dimensional (2D) characterization and 3D mechanical planimetry. This study presents a recipe to create an ultrasonic phantom that simulates a diseased carotid artery segment and how it can be used in identifying the 2D and 3D US interobservation variability. Methods —We created five tissue-like phantoms to simulate various types of diseased plaque segments. To simulate the plaque, a piece of frankfurter was cut and detailed to represent various forms of diseased plaque. Each mould contained dissimilar types of mimicked-plaque, including a soft-plaque, fissured, ulcerated, irregular surfaced, and calcified segment. We used a mixture of gelatin and Metamucil to mimic a previously published soft-tissue mixture. To create a vessel, we used a powder-free, nitrile examination glove. The frankfurter was held in place inside the middle finger of the glove using adhesive gel and filled with mineral oil. Preparation included interval refrigeration of the concoction of the mould. Trained sonographers imaged the plaque using a linear small parts probe for 2D and a mechanical 3D probe for 3D US. Two neuroradiologists assessed the corresponding images and reported their findings including the internal plaque contents, volume, and geometry. Analysis was performed on the inter-observation and inter-reading variability. Results —Interobserver and interreader reliabilities were high, and plaque volume measurement variability decreased with increasing plaque volume. There was increased sensitivity and specificity for each plaque phantom with the use of 3D versus 2D alone. Neuroradiologists reports were 96% sensitive and 97% specific, respectively, when they used combined 2D and 3D US. Conclusion —We created a 2D and 3D vascular US carotid phantom. This phantom is an excellent educational tool to simulate various degrees of diseased carotid segments; moreover, it can be made easily and inexpensively and is reusable. This phantom represents the vessel anatomy and pathology extremely well. We implemented a standardized scanning protocol and created a plaque morphological worksheet to cover all plaque characterization criteria and achieve optimal imaging. Results indicated minimal interobservation and interreader variability. Additional studies are required to address the phantom's longevity and whether or not it can improve the sonographer's skills.

Peripheral MR Neurography

The magnetic resonance neurography (MRN) examination is rapidly becoming a part of the diagnostic algorithm of patients with peripheral neuropathy; however, because of the technical demands and the lack of required reading skills, the examination is relatively underutilized and is currently limited to a few tertiary care centers. The radiologists with interest in peripheral nerve imaging should be able to perform and interpret this examination to exploit its potential for widespread use. This article outlines the systematic, stepwise approach to its interpretation and a brief discussion of the imaging pitfalls.

Application of Basic Principles of Physics to Head and Neck MR Angiography: Troubleshooting for Artifacts

Neurovascular imaging studies are routinely used for the assessment of headaches and changes in mental status, stroke workup, and evaluation of the arteriovenous structures of the head and neck. These imaging studies are being performed with greater frequency as the aging population continues to increase. Magnetic resonance (MR) angiographic imaging techniques are helpful in this setting. However, mastering these techniques requires an in-depth understanding of the basic principles of physics, complex flow patterns, and the correlation of MR angiographic findings with conventional MR imaging findings. More than one imaging technique may be used to solve difficult cases, with each technique contributing unique information. Unfortunately, incorporating findings obtained with multiple imaging modalities may add to the diagnostic challenge. To ensure diagnostic accuracy, it is essential that the radiologist carefully evaluate the details provided by these modalities in light of basic physics principles, the fundamentals of various imaging techniques, and common neurovascular imaging pitfalls.

Educational Exhibit Abstract No. 275 - IR in trauma

Learning Objectives To review various signs and techniques in undertaking an angiogram of trauma patients. Where applicable, correlation with cross sectional imaging will be provided. Background Trauma is a leading cause of mortality with over 5 million people succumbing to it each year. Unrecognized and uncontrolled haemorrhage is the primary cause of early mortality. Whilst surgery remains the standard of care in paitents with haemodynamic instablility and abdominal injury, embolisation is making rapid strides in this area. Trauma management is now a multidisciplinary team approach and interventionalists are finding themselves in a position where they are asked to unexpectedly help manage trauma patients with increasing frequency. Success rates of greater than 90% have been reported when embolisation was used either as a first line therapy, after a vascular complication, or after surgical failure to achieve haemostasis. Success of the interventional procedure requires both prompt recognition of sometimes subtle signs as well as adequate emergent treatment. Unnecessary surgery can often be avoided or the procedure can assist the surgeon in the creation of a relatively bloodless field, particularly for pelvic trauma. Clinical Findings/Procedure Details As a level I trauma centre, IR at our institution is involved in managing multiple types of trauma. We undertake embolisation both in the angio suite and in the operating theatre just prior to surgery. The goal of this presentation is to familiarize the reader to various angiographic signs of traumatic injury such as active extravasation, pruning of vessels, traumatic AV fistulas, To name a few Case examples will be presented and will include subtle findings which can easily be missed. Imaging will cover various organ systems like the pelvic, hepatic, and splenic vasculature. Discussion will cover techniques and pitfalls in imaging. Controversial topics such as management of pruned vessel, the need for being super selective, and embolisation in the operating theatre will be discussed. Conclusion and/or Teaching Points At the end, the reader should be comfortable not only in recognizing but treating the trauma patient, a facet of IR that needs to be bread and butter for all interventionalists.

Pitfalls in the Staging Squamous Cell Carcinoma of the Hypopharynx

To accurately interpret pretreatment and posttreatment imaging in patients with hypopharyngeal squamous cell carcinoma (SCC), one must understand the complex anatomy of this part of the aerodigestive system. Common patterns of spread must be recognized, andpitfalls in imaging must be understood. This article reviews the epidemiology, anatomy, staging, treatment, and pitfalls in imaging of hypopharyngeal SCC.

Sylvian Fissure Lipoma Associated with Middle Cerebral Artery Aneurysm – Report of a Rare Case Highlighting Imaging Pitfalls

Sylvian Fissure Lipoma Associated with Middle Cerebral Artery Aneurysm – Report of a Rare Case Highlighting Imaging Pitfalls

Fluoro-deoxy-glucose positron emission tomography/computed tomography in lymphoma: A pictorial essay

F-18 fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has emerged as a powerful imaging modality in the field of oncology. F-18 FDG PET/CT is now an established tool in the management of lymphoma. This has been shown to be useful in staging, detection of bone marrow involvement (BMI), early response assessment and end of therapy response assessment in lymphoma. Interpretation of F-18 FDG PET/CT in lymphoma is carried out by various qualitative response assessment criteria. London criteria are used for interpretation of interim PET/CT and International Harmonization Project (IHP) criteria are used to interpret PET/CT done after the end of chemotherapy. Quantitative analysis is also found to be useful in assessment of response early after two cycles of chemotherapy in patients with diffuse large B cell lymphoma (DLBCL). This pictorial essay provides few images describing the FDG avidity of lymphoma, patterns of bone marrow uptake and their relevance in predicting BMI, role of staging PET/CT, quantitative analysis in response assessment, example images of response according to London criteria and IHP criteria. Few pitfalls in imaging of lymphoma with PET/CT are also discussed in the images legend.

Anomalies, Anatomic Variants, and Sources of Diagnostic Pitfalls in Pancreatic Imaging

In this review, a brief discussion of the important events of pancreatic embryology is followed by presentation of congenital anomalies and normal variants. For each variant, the appearance at different radiologic modalities including computed tomography, magnetic resonance (MR) imaging, endoscopic retrograde cholangiopancreatography, MR cholangiopancreatography, and fluoroscopy will be demonstrated.

Virtual colonoscopy: Utility, impact and overview

Computed tomography (CT) colonoscopy is a well-established technique for evaluation of colorectal cancer. Significant advances have been made in the technique of CT colonoscopy since its inception. Excellent results can be achieved in detecting both colorectal cancer and significant sized polyps as long as a meticulous technique is adopted while performing CT colonoscopy. Furthermore, it is important to realize that there is a learning curve involved in interpreting these studies and adequate experience is essential to achieve high sensitivity and specificity with this technique. Indications, contraindications, technique and interpretation, including potential pitfalls in CT colonoscopy imaging, are reviewed in this article. Recent advances and the current role of CT colonoscopy in colorectal cancer screening are also discussed.

Liver-specific agents for contrast-enhanced MRI: role in oncological imaging

Liver-specific magnetic resonance (MR) contrast agents are increasingly used in evaluation of the liver. They are effective in detection and morphological characterization of lesions, and can be useful for evaluation of biliary tree anatomy and liver function. The typical appearances and imaging pitfalls of various tumours at MR imaging performed with these agents can be understood by the interplay of pharmacokinetics of these contrast agents and transporter expression of the tumour. This review focuses on the applications of these agents in oncological imaging.