Detecting the Uncommon Imaging Manifestations of Posterior Reversible Encephalopathy Syndrome (PRES) in Adults: a Comprehensive Illustrated Guide for the Trainee Radiologist.

Posterior reversible encephalopathy syndrome (PRES) has traditionally been described as a reversible leukoencephalopathy with a distinct pattern of posteriorly distributed vasogenic oedema involving the subcortical regions of parietal and occipital lobes. PRES commonly occurs in the setting of hypertensive emergencies, pre-eclampsia/eclampsia, impaired renal function, and immunosuppressive therapy. The various clinical presentations of PRES include encephalopathy, seizures, headache, visual, and focal neurological deficits. As knowledge of this entity grows, the range of clinical, and radiological features is seen to be much broader than originally described. The brain oedema may not always be posteriorly distributed and the syndrome may not be uniformly reversible. Of special note are some uncommon imaging features (unilateral cerebral involvement, and isolated posterior fossa involvement) and also some uncommon complications (haemorrhage, cytotoxic oedema, and vasoconstriction). These red herrings may lead to potential diagnostic challenges and pitfalls especially for trainee radiologists, who often read these scans in an emergency setting. Early and accurate diagnosis is crucial for prompt optimum management, thereby avoiding residual morbidity. This review article focusses on the atypical radiological features of PRES in adults with extensive case-based imaging examples. A brief description of the pathophysiology, clinical, and classic radiological features of PRES has also been included. A tabulated summary of potential mimics with diagnostic pearls is provided to highlight pertinent take home points and to serve as an easy guide for day-to-day clinical practice.

Post-Traumatic Carotid Artery Dissection Begins at the Skull Base: A Case Report.

Cervical artery dissection is a rare complication of head and neck trauma. Though it is an infrequent cause of ischaemic stroke, it is more common among the young with cerebral ischaemia. The usual location of carotid dissection is just beyond the carotid bulb. We report a case of post-traumatic internal carotid dissection that began at the base of the skull after blunt head trauma from a road traffic accident. The patient is a 25-year-old right-handed lady who, 2 days after the accident, developed dysphasia and right-sided limb weakness. She had no significant past medical history. Magnetic resonance imaging (MRI) showed acute ischaemic stroke in the internal watershed regions of the left cerebral hemisphere. MR angiogram revealed focal near-occlusion of the left internal carotid artery at the base of the skull just prior to its entry into the petrous temporal bone. There were no skull fractures. She progressed despite anticoagulation. The location of the site of dissection at the base of the skull is likely due to stresses on the carotid intima at this point during flexion-extension-rotation that occurs during head injury, as this is where the internal carotid artery is tethered to the skull. Rapid recognition of symptoms of cerebral ischaemia among patients with blunt head trauma is needed to allow prompt investigation and institution of relevant therapies.

High resolution MRI of nail tumors and tumor-like conditions.

Although the nail is a small anatomical structure, it can be affected by various tumors and tumor-like conditions. Because of the distinctive nail anatomy, the clinical presentation of tumors is modified, thus rendering the diagnosis challenging. As nail biopsy and surgery are painful procedures associated with an increased risk of permanent onychodystrophy, pre-operative diagnosis is desirable. Although conventional radiographs are still the first-line radiologic examination for the assessment of bony structures beneath the nail matrix, they do not allow detailed evaluation of the phalangeal soft tissues. High resolution MRI allows accurate detection and mapping of nail lesions and can suggest a specific diagnosis. This review focuses on high resolution MRI of nail tumors and tumor-like lesions. We review the nail anatomy and the optimal MRI protocol. We then discuss a variety of tumors and tumor-like lesions in relation to the clinical presentation, anatomic location, histological features and imaging characteristics. We herewith describe common benign tumors (glomus tumor, onychomatricoma, keratoakanthoma, fibroma, subungual exostosis, hemangioma, chondroma, pyogenic granuloma), malignant tumors (subungual melanoma, subungual squamous cell carcinoma), as well as tumor mimics (mucoid cyst, epidermoid cyst). Although not entirely specific, MRI is a valuable tool in treatment planning of these tumors.

Masses of developmental and genetic origin affecting the paediatric craniofacial skeleton.

Although rare, masses and mass-like lesions of developmental and genetic origin may affect the paediatric craniofacial skeleton. They represent a major challenge in clinical practice because they can lead to functional impairment, facial deformation and disfigurement. The most common lesions include fibrous dysplasia, dermoid cysts, vascular malformations and plexiform neurofibromas. Less common lesions include torus mandibularis and torus palatinus, cherubism, nevoid basal cell carcinoma syndrome, meningoencephalocele and nasal sinus tract. This article provides a comprehensive approach for the evaluation of children with masses or mass-like lesions of developmental and genetic origin affecting the craniofacial skeleton. Typical findings are illustrated and the respective roles of computed tomography (CT), cone beam CT (CBCT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) sequences and ultrasonography (US) are discussed for the pre-therapeutic assessment, complex treatment planning and post-treatment surveillance. Key imaging findings and characteristic clinical manifestations are reviewed. Pitfalls of image interpretation are addressed and how to avoid them. TEACHING POINTS: • Masses of developmental and genetic origin may severely impair the craniofacial skeleton. • Although rare, these lesions have characteristic imaging features. • CT, MRI and ultrasonography play a key role in their work-up. • Recognition of pivotal imaging pearls and diagnostic pitfalls avoids interpretation errors.

Utility of MRI with morphologic and diffusion weighted imaging in the detection of post-treatment nodal disease in head and neck squamous cell carcinoma.

PURPOSE: To determine the diagnostic performance of morphologic MRI with diffusion weighted imaging (DWIMRI) for the detection of post-treatment lymph node (LN) recurrence of head and neck squamous cell carcinoma (HNSCC). METHODS: This retrospective study is based on 33 HNSCC patients who underwent DWIMRI with apparent diffusion coefficient (ADC) measurements for suspected post-treatment loco-regional failure. Two radiologists, blinded to clinical/histopathological data, analyzed MR images according to established morphologic criteria and measured ADC values by drawing regions of interest on each normal/abnormal looking lymph node (LN). Histopathological findings in 40 neck dissections, 133 LN-levels and 755 LNs served as gold standard. RESULTS: Malignant LNs had lower ADCmean values than benign LNs (1.15 ±â€¯0.35 × 10-3 mm2/s versus 1.28 ±â€¯0.28 × 10-3 mm2/s, p = .028). The optimal ADCmean threshold to differentiate malignant from benign LNs was 1.1695 × 10-3 mm2/s. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values (95%CI in parentheses) of DWIMRI with morphologic criteria and ADCmean <1.1695 × 10-3 mm2/s were: (a) 100%(86.2;100), 44.4%(15.3;77.3), 86.1%(69.7;94.7), and 100%(39.5;100) per neck dissection; (b) 83.6%(69.7;92.2), 91.6%(83.0;96.2), 85.4%(71.6;93.4), and 90.5%(81.7;95.5) per LN-level; (c) 53.1%(43.5;62.4), 95.5%(93.5;96.9), 67.4%(56.6;76.7), and 92.0%(89.6;93.9) per LN, respectively. CONCLUSION: The high NPV of DWIMRI irrespective of analysis type (per neck dissection/per neck level/per lymph node) make it a useful follow-up tool after treatment.

Novel use of non-echo-planar diffusion weighted MRI in monitoring disease activity and treatment response in active Grave's orbitopathy: An initial observational cohort study.

AIM: To examine the novel use of non-echo-planar diffusion weighted MRI (DWI) in depicting activity and treatment response in active Grave's orbitopathy (GO) by assessing, with inter-observer agreement, for a correlation between its apparent diffusion coefficients (ADCs) and conventional Short tau Inversion Recovery (STIR) MRI signal-intensity ratios (SIRs). METHOD AND MATERIALS: A total of 23 actively inflamed muscles and 30 muscle response episodes were analysed in patients with active GO who underwent medical treatment. The MRI orbit scans included STIR sequences and non-echo-planar DWI were evaluated. Two observers independently assessed the images qualitatively for the presence of activity in the extraocular muscles (EOMs) and recorded the STIR signal-intensity (SI), SIR (SI ratio of EOM/temporalis muscle), and ADC values of any actively inflamed muscle on the pre-treatment scans and their corresponding values on the subsequent post-treatment scans. Inter-observer agreement was examined. RESULTS: There was a significant positive correlation (0.57, p < 0.001) between ADC and both SIR and STIR SI of the actively inflamed EOM. There was also a significant positive correlation (0.75, p < 0.001) between SIR and ADC values depicting change in muscle activity associated with treatment response. There was good inter-observer agreement. CONCLUSION: Our preliminary results indicate that quantitative evaluation with non-echo-planar DWI ADC values correlates well with conventional STIR SIR in detecting active GO and monitoring its treatment response, with good inter-observer agreement.

Carotidynia: A Rare Diagnosis for Unilateral Neck Pain Revealed by Cross-Sectional Imaging.

Idiopathic carotidynia (IC) is a rare and poorly understood syndrome consisting of unilateral neck pain, tenderness, and increased pulsations over the affected carotid bifurcation. A growing body of evidence supports the hypothesis that IC is a distinct clinicopathologic entity with characteristic imaging features. We report the case of a 34-year-old Caucasian male presenting with intense unilateral neck pain in the emergency setting. Computed tomography and ultrasonography revealed fusiform eccentric thickening of the ipsilateral carotid bifurcation without vessel narrowing. Contrast-enhanced magnetic resonance imaging depicted major perivascular enhancement without evidence of dissection. Further imaging and laboratory work-up excluded vasculitis. The diagnosis of IC was made. The patient was treated with nonsteroidal anti-inflammatory drugs and symptoms and imaging findings disappeared within a few weeks. Cross-sectional imaging allows not only ruling out IC mimickers but also making the correct diagnosis of this rare condition, in particular, as the clinical presentation of IC is often nonspecific.

Injectable facial fillers: imaging features, complications, and diagnostic pitfalls at MRI and PET CT.

Injectable fillers are widely used for facial rejuvenation, correction of disabling volumetric fat loss in HIV-associated facial lipoatrophy, Romberg disease, and post-traumatic facial disfiguring. The purpose of this article is to acquaint the reader with the anatomy of facial fat compartments, as well as with the properties and key imaging features of commonly used facial fillers, filler-related complications, interpretation pitfalls, and dermatologic conditions mimicking filler-related complications. The distribution of facial fillers is characteristic and depends on the anatomy of the superficial fat compartments. Silicone has signature MRI features, calcium hydroxyapatite has characteristic calcifications, whereas other injectable fillers have overlapping imaging features. Most fillers (hyaluronic acid, collagen, and polyalkylimide-polyacrylamide hydrogels) have signal intensity patterns compatible with high water content. On PET-CT, most fillers show physiologic high FDG uptake, which should not be confounded with pathology. Abscess, cellulitis, non-inflammatory nodules, and foreign body granulomas are the most common filler-related complications, and imaging can help in the differential diagnosis. Diffusion weighted imaging helps in detecting a malignant lesion masked by injected facial fillers. Awareness of imaging features of facial fillers and their complications helps to avoid misinterpretation of MRI, and PET-CT scans and facilitates therapeutic decisions in unclear clinical cases. KEY POINTS: • Facial fillers are common incidental findings on MRI and PET-CT scans. • They have a characteristic appearance and typical anatomic distribution • Although considered as safe, facial filler injections are associated with several complications • As they may mask malignancy, knowledge of typical imaging features is mandatory. • MRI is a problem-solving tool for unclear cases.

Suprasellar pilocytic astrocytoma in an adult with hemorrhage and leptomeningeal dissemination: case report and review of literature.

Pilocytic astrocytoma (PA) is a low-grade tumor. It has an excellent prognosis after total resection. Leptomeningeal dissemination and hemorrhage are very rare to be associated with PA and lead to unfavorable prognosis. A 35-year-old man was diagnosed with a hemorrhagic suprasellar PA in 2006. Subsequent examination in 2007 revealed another large subdural hemorrhagic lesion in the sacral region, which proved to be PA by histopathologic assessment. Other leptomeningeal foci were discovered mainly at the craniocervical junction. The patient underwent subtotal resection and received chemotherapy with disease control for 7 years. Progression of the disseminated disease has recently occurred; however, the patient is still alive with stable disease after radiotherapy. The radiological features, management, and relevant literature are also presented. Our report heightens the awareness of PA in the adult population and the importance of close surveillance for the leptomeningeal spread, especially for sellar region tumors.

The pterygopalatine fossa: imaging anatomy, communications, and pathology revisited.

UNLABELLED: The pterygopalatine fossa (PPF) is a small, clinically inaccessible, fat-filled space located in the deep face that serves as a major neurovascular crossroad between the oral cavity, nasal cavity, nasopharynx, orbit, masticator space, and the middle cranial fossa. Due to its inherent complex location and connections, it can potentially act as a natural conduit for the spread of inflammatory and neoplastic diseases across the various deep spaces in the head and neck. This review aims to acquaint the reader with the imaging anatomy of the PPF, its important communications, and to identify some major pathological conditions that can involve the PPF, especially in conditions where its involvement can have serious diagnostic and therapeutic implications, such as in perineural tumour spread. TEACHING POINTS: • The PPF is a small neurovascular junction in the deep face with important to-and-fro connections. • Awareness of anatomy of the PPF and its communications helps to simplify imaging of its pathology. • Perineural tumour spread is clinically the most important pathology in this region.

Imaging of facial nerve schwannomas: diagnostic pearls and potential pitfalls.

Schwannomas are uncommon in the facial nerve and account for less than 1% of tumors of temporal bone. They can involve one or more than one segment of the facial nerve. The clinical presentations and the imaging appearances of facial nerve schwannomas are influenced by the topographical anatomy of the facial nerve and vary according to the segment(s) they involve. This pictorial essay illustrates the imaging features of facial nerve schwannomas according to their various anatomical locations and also reviews the pertinent differential diagnoses and potential diagnostic pitfalls.

CT arteriography and venography in the evaluation of Pulsatile tinnitus with normal otoscopic examination.

OBJECTIVES/HYPOTHESIS: Our retrospective study aims to assess the ability of computed tomography arteriography and venography (CT A/V) to detect various findings that suggest a potential cause of pulsatile tinnitus and to examine the association between these findings and the side of pulsatile tinnitus. STUDY DESIGN: A retrospective review of CT arteriography and venography of 32 patients with established pulsatile tinnitus and normal otoscopic examination was performed. The scans were performed using a 64-slice multidetector scanner and were reviewed to look for findings that are known to cause pulsatile tinnitus. RESULTS: One or more findings that are known to cause pulsatile tinnitus were detected on the symptomatic side in 30 patients; on the asymptomatic side in 3 patients, one patient with bilateral pulsatile tinnitus showed a potential cause of symptoms only on one side, and in one patient no potential cause could be identified. There is a significant association seen between the side of pulsatile tinnitus and various potential causes of pulsatile tinnitus detected (P < 0.001), between the side of pulsatile tinnitus and various potential venous cause detected (P < 0.001), and between the side of pulsatile tinnitus and the side of dominant venous system (P = 0.02). CONCLUSION: CT arteriography and venography is a useful tool in detecting many described potential causes of pulsatile tinnitus. Significant association is demonstrated between the side of pulsatile tinnitus and the potential causes of pulsatile tinnitus detected by CT arteriography and venography when the otoscopic examination is normal.