Image-guided percutaneous procedures have increasingly been established as safe and effective interventional tools in the diagnosis and management of masses and collections in several body segments. However, lesions in deep pelvic sites still pose a challenge for radiologists because of overlying anatomic structures. The success of a percutaneous biopsy depends on a safe access route planning based on a deep understanding of cross sectional anatomy of the pelvis. Anterior and lateral transabdominal, anterolateral extraperitoneal, transvaginal, transrectal and transgluteal approaches are described. The present study was aimed at reviewing the normal pelvic cross-sectional anatomy, demonstrating the different access routes for ultrasonography and computed tomography guided pelvic biopsies and drainages as well as discussing the main advantages and complications associated with these approaches.

Keywords: Biopsies, Percutaneous drainage, Interventional procedures, Pelvic anatomy, Pelvic abscesses

The iliopsoas compartment, a posterior boundary of the retroperitoneum, is comprised of the psoas major, psoas minor and iliac muscles. The symptoms picture in patients presenting with pathological involvement of this compartment may show a wide range of nonspecific clinical presentations that may lead to delayed diagnosis. However, in the search of an etiological diagnosis, it is already known that inflammation, tumors, and hemorrhages account for almost all the lesions affecting the iliopsoas compartment. By means of a retrospective analysis of radiological studies in patients with iliopsoas compartment lesions whose diagnosis was confirmed by anatomopathological evaluation or clinical follow-up, we have reviewed its anatomy as well as the main forms of involvement, with the purpose of identifying radiological signs that may help to narrow down the potential differential diagnoses. As each lesion is approached we will discuss the main radiological findings such as presence of gas in pyogenic abscesses, bone destruction and other bone changes of vertebral bodies in lesions secondary to tuberculosis, involvement of fascial planes in cases of neoplasms, and differences in signal density and intensity of hematomas secondary to hemoglobin degradation, among others. So, we have tried to present cases depicting the most frequent lesions involving the iliopsoas compartment, with emphasis on those signs that can lead us to a more specific etiological diagnosis.

Keywords: Iliopsoas muscle, Psoas muscle, Computed tomography, Abscesses, Neoplasms

OBJECTIVE: To determine and compare the efficacy of percutaneous needle aspiration and percutaneous catheter drainage, both guided by imaging methods, for the treatment of liver abscesses. MATERIALS AND METHODS: From 52 patients referred to our service for percutaneous treatment of abdominal abscesses, 17 presented liver abscesses, 13 of which were considered noncomplex and four were considered complex (multiloculated, multiple or associated to fistulas). Percutaneous needle aspiration was performed in 7/17 patients and 10/17 patients were submitted to percutaneous catheter drainage. The method used was considered successful when there was complete abscess resolution with both clinical and laboratorial improvement. RESULTS: The procedures were successful in 82.4% of all cases. In the group submitted to percutaneous needle aspiration the rate of success was 57.1% and in the group submitted to percutaneous catheter drainage the rate of success was 100%. Successful treatment was achieved in 75% of the patients submitted to percutaneous needle aspiration for abscesses smaller than 100 ml, but in only 33.3% of the patients with abscesses between 100 and 250 ml. There was complete resolution of the abscesses with percutaneous needle aspiration in 75% of the simple abscesses and in 25% of the complex abscesses. CONCLUSION: Percutaneous catheter drainage is more effective than percutaneous needle aspiration for the treatment of liver abscesses. Needle aspiration may probably be used as a valid alternative for smaller and noncomplex abscesses.

Keywords: Liver abscesses, Percutaneous needle aspiration, Percutaneous catheter drainage

The knowledge of meniscal anatomic variants and of the normal perimeniscal structures is essential to understand magnetic resonance imaging studies of the knee, both for the diagnosis of meniscal lesions and to avoid potential interpretation pitfalls. The present article reviews anatomic variants that change the size, shape and stability of the menisci, including the different types of discoid menisci, other less frequent meniscal malformations and the meniscal ossicle. Additionally, the anatomy of perimeniscal structures, particularly those including the meniscocapsular, intermeniscal, meniscofemoral ligaments and other menisco-ligamentous structures is reviewed.

Keywords: Knee; Discoid meniscus; Anatomic variants; Magnetic resonance imaging.

Conventional angiography is still considered the gold standard for the study of the anatomy and of vascular diseases of the abdomen. However, the advent of multidetector computed tomography and techniques of digital image reconstruction has provided an alternative means of performing angiography, without the risks inherent to invasive angiographic examinations. Therefore, within the field of radiology, there is an ever-increasing demand for deeper knowledge of the anatomy of the regional vasculature and its variations. Variations in the renal vascular system are relatively prevalent in the venous and arterial vessels. For various conditions in which surgical planning is crucial to the success of the procedure, knowledge of this topic is important. The aim of this study was to familiarize the general radiologist with variations in the renal vascular system. To that end, we prepared a pictorial essay comprising multidetector computed tomography images obtained in a series of cases. We show patterns representative of the most common anatomical variations in the arterial blood supply to the kidneys, calling attention to the nomenclature, as well as to the clinical and surgical implications of such variations.

Keywords: Anatomic variation; Renal artery; Multidetector computed tomography.

OBJECTIVE: To develop a simulator for training In fluoroscopy-guided facet joint Injections and to evaluate the learning curve for this procedure among radiology residents. MATERIALS AND METHODS: Using a human lumbar spine as a model, we manufactured five lumbar vertebrae made of methacrylate and plaster. These vertebrae were assembled in order to create an anatomical model of the lumbar spine. We used a silicon casing to simulate the paravertebral muscles. The model was placed into the trunk of a plastic mannequin. From a group of radiology residents, we recruited 12 volunteers. During simulation-based training sessions, each student carried out 16 lumbar facet injections. We used three parameters to assess the learning curves: procedure time; fluoroscopy time; and quality of the procedure, as defined by the positioning of the needle. RESULTS: During the training, the learning curves of all the students showed improvement in terms of the procedure and fluoroscopy times. The quality of the procedure parameter also showed improvement, as evidenced by a decrease in the number of inappropriate injections. CONCLUSION: We present a simple, inexpensive simulation model for training in facet joint injections. The learning curves of our trainees using the simulator showed improvement in all of the parameters assessed.

Keywords: Zygapophyseal joint; Injections, intra-articular; Injections, spinal; Learning curve; Models, anatomic; Radiology, interventional.