Head and Neck Paragangliomas: An Update on the Molecular Classification, State-of-the-Art Imaging, and Management Recommendations.

Paragangliomas are neuroendocrine tumors that derive from paraganglia of the autonomic nervous system, with the majority of parasympathetic paragangliomas arising in the head and neck. More than one-third of all paragangliomas are hereditary, reflecting the strong genetic predisposition of these tumors. The molecular basis of paragangliomas has been investigated extensively in the past couple of decades, leading to the discovery of several molecular clusters and more than 20 well-characterized driver genes (somatic and hereditary), which are more than are known for any other endocrine tumor. Head and neck paragangliomas are largely related to the pseudohypoxia cluster and have been previously excluded from most molecular profiling studies. This review article introduces the molecular classification of paragangliomas, with a focus on head and neck paragangliomas, and discusses its impact on the management of these tumors. Genetic testing is now recommended for all patients with paragangliomas to provide screening and surveillance recommendations for patients and relatives. While CT and MRI provide excellent anatomic characterization of paragangliomas, gallium 68 tetraazacyclododecane tetraacetic acid-octreotate (ie, 68Ga-DOTATATE) has superior sensitivity and is recommended as first-line imaging in patients with head and neck paragangliomas with concern for multifocal and metastatic disease, patients with known multifocal and metastatic disease, and in candidates for targeted peptide-receptor therapy. Keywords: Molecular Imaging, MR Perfusion, MR Spectroscopy, Neuro-Oncology, PET/CT, SPECT/CT, Head/Neck, Genetic Defects © RSNA, 2022.

The "pool sign" of metastatic adenocarcinoma.

The differential of a newly discovered solitary intracranial mass is a primary intracranial neoplasm and metastatic disease. Differentiating between the two entities on imaging is difficult, though there are clues on conventional imaging that suggest one over the other. The purpose of this article is to describe a new imaging finding on T2-weighted imaging, the "pool sign," that may be specific for metastatic adenocarcinomas and can help differentiate a solitary metastasis from a primary CNS neoplasm. We present a series of four patients with initial magnetic resonance imaging of a solitary intracranial mass demonstrating the "pool sign," and therefore predicted to be metastatic adenocarcinoma. All of these cases were confirmed to be metastatic adenocarcinoma on pathology.

Diagnostic clues to ectopic pregnancy.

Ectopic pregnancy accounts for approximately 2% of all pregnancies and is the most common cause of pregnancy-related mortality in the first trimester. Initial evaluation consists of hormonal assays and pelvic ultrasonography (US). A history of pelvic pain along with an abnormal beta human chorionic gonadotropin level should trigger an evaluation for an ectopic pregnancy. The fallopian tube is the most common location for an ectopic pregnancy. An adnexal mass that is separate from the ovary and the tubal ring sign are the most common findings of a tubal pregnancy. Other types of ectopic pregnancy include interstitial, cornual, ovarian, cervical, scar, intraabdominal, and heterotopic pregnancy. Interstitial pregnancy occurs when the gestational sac implants in the myometrial segment of the fallopian tube. Cornual pregnancy refers to the implantation of a blastocyst within the cornua of a bicornuate or septate uterus. An ovarian pregnancy occurs when an ovum is fertilized and is retained within the ovary. Cervical pregnancy results from an implantation within the endocervical canal. In a scar pregnancy, implantation takes place within the scar of a prior cesarean section. In an intraabdominal pregnancy, implantation occurs within the intraperitoneal cavity. Heterotopic pregnancy occurs when an intrauterine and an extrauterine pregnancy occur simultaneously. A spectrum of intra- and extrauterine findings may be seen on US images. Although many of the US findings are nonspecific by themselves, when several of them are seen, the specificity of US in depicting an ectopic pregnancy substantially improves.

The importance of monophasic Doppler waveforms in the common femoral vein: a retrospective study.

OBJECTIVE: The purpose of this study was to assess the importance of monophasic waveforms encountered in the common femoral vein during deep venous thrombosis evaluation by a retrospective review of lower extremity venous Doppler (VD) sonography and correlative studies, such as computed tomography (CT) and magnetic resonance imaging. METHODS: A retrospective review was conducted of lower extremity VD studies performed from September 1, 2000, through September 1, 2005. All satisfactory VD studies, which were in compliance with the Intersocietal Commission for the Accreditation of Vascular Laboratories standard protocol, were evaluated for the presence of monophasic waveforms and correlated with CT of the abdomen and pelvis. Studies were evaluated for the causes of monophasic waveforms. Patients younger than 18 years were excluded. RESULTS: A total of 2963 VD examinations were reviewed. One hundred twenty-four of 2963 showed monophasic waveforms. Eighty-nine of the 124 had additional CT examinations within 1 week; 19 had CT within 2 months; and 16 had no additional examinations. Forty-seven of 124 cases revealed deep venous thrombosis extending into the iliac veins, of which 23 were identified by VD sonography; 26 were due to extrinsic compression; 6 showed a hypoplastic or stenosed common iliac vein; and the remaining 45 had no apparent causes for the monophasic waveforms. CONCLUSIONS: Monophasic waveforms in the common femoral veins are reliable indicators of proximal venous obstruction. Because iliac vein thrombosis is clinically important, we recommend routine sonographic evaluation of external iliac veins in the presence of monophasic waveforms and CT or magnetic resonance imaging, if necessary, to determine the cause of the monophasic waveforms.

Vertebroplasty: cement leakage into the disc increases the risk of new fracture of adjacent vertebral body.

BACKGROUND AND PURPOSE: Patients successfully treated with vertebroplasty often return with new pain caused by a new vertebral body fracture. The new fractures often are adjacent to the vertebral bodies that were initially treated. In our clinical work, we have observed that cement leakage into the disk increases the risk of new fracture of the adjacent vertebral body. This study analyzed the risk of new fractures of adjacent vertebral bodies in relationship to cement leakage into the disk. METHODS: This study was based on 38 patients with painful compression fractures treated with vertebroplasty. Patients who returned with new pain after initial successful vertebroplasty were evaluated by repeat MR imaging. We analyzed the incidence of new fractures of adjacent vertebral bodies in relationship to cement leakage into the disk that had occurred during the initial vertebroplasty. RESULTS: Fourteen patients developed new fractures during the follow-up period. In 10 patients, the new fractures were associated with cement leakage into the disk, whereas four patients had new fractures that were not associated with cement leakage into the disk. This difference was statistically significant (P =.018). A detailed analysis showed that 58% of vertebral bodies adjacent to a disk with cement leakage fractured during the follow-up period compared with 12% of vertebral bodies adjacent to a disk without cement leakage (P <.0005). CONCLUSION: Leakage of cement into the disk during vertebroplasty increases the risk of a new fracture of adjacent vertebral bodies.