Renal fascial pathway: posterior extension of pancreatic effusions within the anterior pararenal space

Retrorenal extension of pancreatic effusion or phlegmon associated with pancreatitis has been described frequently and is generally considered to represent extension of these processes from the anterior into the posterior pararenal space. A series of meticulous cadaveric dissections (n = 8) and a review of a large number of patients with pancreatitis (n = 53) show that these posterior collections actually represent extension of pancreatitis from the anterior pararenal space to a potential space between the laminae of the posterior renal fascia. Of 40 patients with posterior extension of pancreatic effusion or phlegmon, interfascial involvement was observed in all 40 and was bilateral in nine (23%). True involvement of the posterior pararenal space was uncommon, as was extension into the perirenal space. This phenomenon appears as a continuum of the well-described thickening of the renal fascia secondary to pancreatitis. It can be explained by new observations of the relationships between the fascia of Gerota and the lateroconal fascia.     

Medial extent of the posterior renal fascia. An anatomic and computed tomography study

To study the medial extent of the posterior renal fascia and the perirenal space, the authors dissected two cadavers and reviewed 50 computed tomographic (CT) abdominal scans. The results demonstrated that the medial extent of the posterior renal fascia depends on the level in a vertical direction and its relationship to the kidney which varies at different levels. At the renal hilus, the fascia inserts posteromedially to the fascia of the quadratus lumborum along its lateral margin; more cranially, the line of insertion is more lateral, onto the diaphragmatic fascia; more caudally, the line of insertion is more medial, inserting onto the anterior surface of the quadratus lumborum. Therefore the posteromedial insertion of the posterior renal fascia extends medially, from the more laterally placed diaphragmatic fascia, to the lateral margin of the quadratus lumborum and then to the anterior surface of the quadratus lumborum, depending on the anatomic level. The clinical implication of these findings are discussed.     

The posterior interparieto-peritoneal or retroperitoneal spaces. 2: Pathological x-ray computed tomographic image

The old reports about the interparieto-peritoneal spaces described particularly the renal space and its environment. The CT scan has modified the in vivo study of the extraperitoneal spaces (E.P.S.) and brought the question of the acquired knowledge up again. An anatomical research was performed in the first part of this study which describes the structures limited between the parietalis fascia and visceral peritoneal fascias. These are the true EPS which the main element is the propria fascia of Sappey (lateroconal fascia) and its anterior and posterior renal double layers. All these lamellar structures limits spaces variably infiltrated with fat tissue: the anterior pararenal space almost virtual, the posterior pararenal space which continues till the Bogros space and the anterior and posterior renal spaces of the renal compartment which the fat continues till the bladder and accompanies the ureter. The second part of this study precises some notions of general topography which are necessary for reading abnormal CT scan images. This part reminds the aortic and arterial general organization of the vertebrates as described by Mackay. It underlines the architectural importance of the three areas so defined: parietal or peripheral, intermediate or mesoblastic genitourinary and deep lateral or digestive endoblastic. These three areas corresponds to the three vascular aortic circles. It emphasized the importance to accept in practice the notion of visceral joining fascia which has been proved in adult people. The longitudinal architecture of the compartments is precise with respect to their appartenance to one among the three arterial arches of Mackay. What the anatomy suggest, the pathology can prove. Several pathological processes are studied on CT scan: large hemorrhagic or necrotic collections in acute pancreatitis, abnormalities or diseases of renal or adrenal compartments, extraperitoneal mesenchymomas, diseases of the psoas compartment. All these observations are analysed in order to explain anatomical and CT scan findings. This study refers not only to the oldest researches which are still valuable but also to the most recent controversies. All the questions are not solved using the clearest schemes.     

The posterior interparietoperitoneal spaces or retroperitoneal spaces. 1: Normal topographic anatomy

The posterior spaces between the wall and peritoneum or extraperitoneal spaces are located between the visceral retrocolic and retro-duodenopancreatic fascias anteriorly and the parietalis fascia posteriorly. They were studied using an anatomic and computed tomographic comparison. The propria fascia (lateroconal fascia) divided into the anterior and posterior layers of the perirenal fascia. The fascias delimitate two anterior and posterior pararenal spaces around the kidney compartment and two anterior and posterior perirenal spaces in the compartment itself. These spaces extended above and below the renal compartment from the diaphragm to the pelvis. These large spaces composed of fat and organs can assume the guided migration of pathologic processes or their spread according to the importance of the fascias barriers. They below to the genito-urinary region. The extraperitoneal spaces are related anteriorly to the retroperitoneal alimentary organs: duodenum, pancreas, ascending and descending colon depending of the alimentary region. They are related posteriorly with the abdominal wall and its own fat. The individuality and the interdependance of these three territories (alimentary, genito-urinary and abdominal wall) and their consequences for pathologic CT scan imaging will be discussed in the second part of this paper.     

肾后筋膜解剖分层的CT研究

目的 探讨成人肾后筋膜解剖分层的CT特点.方法 收集85例急性胰腺炎(AP)患者的临床和影像学资料,观察和分析CT图像上成人的肾后筋膜有无分层及其解剖分型.结果 (1)23例患者的左侧肾后筋膜显示分层,9例患者的右侧肾后筋膜显示分层,8例患者的双侧肾后筋膜均显示有分层;(2)肾后筋膜分层表现为:肾后筋膜全程分层以及单纯肾后筋膜外侧部分分层,其中左侧肾后筋膜全程分层者6例,单纯外侧分层者17例;右侧肾后筋膜全程分层者4例,单纯外侧分层者5例,双侧肾后筋膜全程分层者4例,单纯外侧分层者4例.结论 CT可显示肾后筋膜的解剖分层;肾后筋膜解剖分层分为2种类型,且双侧可不对称.     

肾前筋膜间平面的CT研究及其临床意义

目的探讨肾前筋膜间平面的解剖及其内侧通连关系。方法回顾性分析CT扫描资料和临床资料完整的40例重症胰腺炎病例,均经临床、实验室检查或手术病理确诊。着重观察左侧肾前筋膜内积液情况和左右两侧的通连关系。结果(1)左侧肾前筋膜内积液28例,右侧肾前筋膜内积液17例;其中双侧肾前筋膜内积液16例。(2)28例左侧肾前筋膜内积液中,积液主要位于内侧者7例,积液主要位于外侧者1例。左侧肾前筋膜内积液与降结肠系膜血管分界清晰者19例。(3)8例显示在肾脏下方层面,双侧肾前筋膜通过中线相互通连,其中2例显示肾前筋膜内积液相互通连。(4)胰周积液进入肾前筋膜内主要通过筋膜的薄弱处或渗入的方式,部分病例为直接破坏筋膜进入筋膜内。结论肾前筋膜内存在筋膜间平面。部分个体中,两侧肾前筋膜间平面在肾脏下方平面相互通连。     

Extraperitoneal paravesical spaces: CT delineation with US correlation

The extraperitoneal space around the urinary bladder is lamellate, just like the retroperitoneal space around the kidneys. The bladder, urachus, and obliterated umbilical arteries lie within the perivesical space, surrounded by umbilicovesical fascia, analogous to the perinephric space within the renal fascia. A much larger prevesical space, analogous to the anterior pararenal space, lies anterior and lateral to the umbilicovesical fascia. Posterior to the urinary bladder, the lower uterine segment or seminal vesicles lie within the perivesical space, rather than in a separate compartment, corresponding to the posterior pararenal space. The cul-de-sac, and the inferolateral extension of its peritoneal layers as the rectovaginal or rectovesical septum, separate the posterior perivesical space from the rectum. The sectional anatomy of these spaces, and particularly their computed tomographic and ultrasound appearances, were noted in normal anatomic sections, patients with extraperitoneal fluid collections, and a cadaver into which fluid was injected.     

Renal vein thrombosis in patients with nephrotic syndrome: CT diagnosis

A retrospective evaluation of the computed tomography (CT) findings in 50 patients with the nephrotic syndrome was undertaken. In four patients with clinical manifestations of acute renal vein thrombosis (RVT) on initial examination, the diagnosis was confirmed by CT findings. Three patients had left RVT, one had right RVT, and all four had thrombus in the inferior vena cava (IVC) at the level of the renal veins. Of the remaining 46, otherwise asymptomatic patients, one had bilateral RVT, two had left RVT, and five had isolated IVC thrombus. The abnormalities noted on CT scans were widened renal vein(s) containing thrombus, thrombus in the IVC, renal enlargement, thickened Gerota fascia and formation of pericapsular venous collaterals, and an abnormal renal parenchymal enhancement pattern consisting of prolonged corticomedullary discrimination, delayed and/or persistent paraenchymal opacification, and delayed or absent pyelocalyceal visualization.     

Bridging septa of the perinephric space: anatomic, pathologic, and diagnostic considerations

The perinephric space is not a simple fat-filled chamber through which fluid may be distributed unhindered. It is divided into multiple compartments by fibrous lamellae, the bridging septa. Some of these structures arise from the renal capsule and extend to the perinephric fascia; others are attached only to the renal capsule and are arranged more or less parallel to the renal surface. Still others connect the anterior to the posterior leaves of the perinephric fascia. The resulting compartments exert an important influence on pathologic processes, resulting, for example, in limitation of the spread of pus and tamponade of bleeding points. The configuration of many perinephric collections can only be understood by knowledge of the existence and arrangement of these lamellae. The current criteria for differentiation of subcapsular from perinephric hematomas are shown to be in error, and a new sign for such differentiation is described. There are also implications regarding therapeutic drainage of perinephric abscesses, particularly by the percutaneous route. A new classification of the perinephric fascia is proposed.     

The anatomical assessment of the renal fascia in the normal subject by using computed tomographic equipment with advanced technology]

One hundred patients, affected with diseases not involving the peri-renal and pararenal spaces, have been examined in order to evaluate the visibility of the renal fasciae, using a CT scanner provided with high spatial and contrast resolution. The anterior renal fascia has been recognized in 71% of cases on the right side and in 88% on the left. The posterior renal fascia had 96% of positive bilateral detectability. The latero-conal fascia was detected in 83% of cases on the right and in 91% on the left. The inter-renal fascia was recognized in 25% of cases, at the pancreas or, more frequently, on caudal planes. The peri-renal septa were seen in 58% of cases, mainly on the left side. Compared to previous data reported by other authors, the visibility of the renal fasciae has been increased by the greater spatial and contrast resolution offered by the new CT scanner, thus allowing better anatomical evaluation of peri and para-renal spaces.     

Comprehensive reviews of the interfascial plane of the retroperitoneum: normal anatomy and pathologic entities

The retroperitoneum is conventionally divided into three distinct compartments: posterior pararenal space, anterior pararenal space, and perirenal space, bounded by the posterior parietal peritoneum, transversalis fascia, and perirenal fascia. But more recent work has demonstrated that the perirenal fascia is not made up of distinct unilaminated fascia, but a single multilaminated structure with potential space. These potential spaces are represented by retromesenteric plane, retrorenal plane, lateral conal plane, and combined fascial plane. The purpose of this review was to demonstrate embryogenesis, anatomy of interfascial plane, and spreading pathways of various pathologic entities with computed tomography imaging.     

Sonography of subfascial hematoma after cesarean delivery

Subfascial hematoma is an important complication of cesarean delivery that has received little attention in the radiologic literature. It results from extraperitoneal hemorrhage within the prevesical space, posterior to the rectus muscles and transversalis fascia but anterior to the peritoneum and umbilicovesical fascia. Subfascial hematomas were found in 12 (38%) of 32 patients referred for sonographic evaluation of a fever or a fall in hemoglobin that occurred after a cesarean delivery. In all cases, sonography revealed cystic or complex masses of various sizes anterior to the bladder. The use of high-frequency, short-focus transducers often was necessary to recognize these superficial abnormalities. Seven of the 12 patients had concomitant bladder-flap hematomas between the lower uterine segment and posterior bladder margin. Of the five remaining patients with isolated subfascial hematomas, the sonograms on four were misinterpreted as showing bladder-flap hematomas. The other was diagnosed correctly. Distinction of subfascial hematomas from bladder-flap hematomas and superficial-wound hematomas must be made if surgical evacuation is contemplated.     

Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings.

Congenital anomalies of the inferior vena cava (IVC) and its tributaries have become more commonly recognized in asymptomatic patients. The embryogenesis of the IVC is a complex process involving the formation of several anastomoses between three paired embryonic veins. The result is numerous variations in the basic venous plan of the abdomen and pelvis. A left IVC typically ends at the left renal vein, which crosses anterior to the aorta to form a normal right-sided prerenal IVC. In double IVC, the left IVC typically ends at the left renal vein, which crosses anterior to the aorta to join the right IVC. In azygos continuation of the IVC, the prerenal IVC passes posterior to the diaphragmatic crura to enter the thorax as the azygos vein. In circumaortic left renal vein, one left renal vein crosses anterior to the aorta and another crosses posterior to the aorta. In retroaortic left renal vein, the left renal vein passes posterior to the aorta. In circumcaval ureter, the proximal ureter courses posterior to the IVC. Other anomalies include absence of the infrarenal IVC or the entire IVC. These anomalies can have significant clinical implications. Awareness of these anomalies is necessary to avoid diagnostic pitfalls.     

Visibility and thickening of the renal fascia on computed tomograms

The renal fascia can be seen on CT scans (using appropriate window settings) in most patients except those with very little fat. CT confirms current anatomical concepts; however, contrary to the illustrations shown in the literature, it clearly demonstrates that the anterior pararenal space normally exists only at the level of the retroperitoneal organs. A lesion would distend the space. While visualization of the renal fascia on normal urograms may be an indication of renal disease, a thin renal fascia on CT scans has no pathological significance. Thickening is nonspecific: it is not pathognomonic of tumor, nor is it helpful in differentiating pancreatitis from neoplasm. On the other hand, lack of fascial thickening may be helpful in ruling out renal extension of a neighboring lesion.     

The superior aspect of the perirenal space: could it be depicted by dual-source CT in vivo in adults

Objective:

This study aims to observe whether the renal fascias could be effectively shown by dual-source CT (DSCT) and to explore the superior communication of the perirenal space (PS) in vivo in adults.

Methods:

275 cases were included in the normal group and 124 cases in the acute pancreatitis group in this study; all images obtained by DSCT were observed; the superior adherence of the renal fascias and the pattern of superior communication of the PS were judged; and the consistency between the two groups was compared.

Results:

The superior adherence of the renal fascias was reliably displayed in 57.8% of the normal group and 69.4% of the acute pancreatitis group, the anterior renal fascia (ARF) did not fuse with the posterior renal fascia superiorly. The left ARF fused with the posterior parietal peritoneum in 57.9% of the normal group and 45.3% of the pancreatitis group, where the left PS communicated with the subdiaphragmatic retroperitoneal space (SDRS). The left ARF fused with the peritoneum laterally and simultaneously with the inferior phrenic fascia medially in 42.1% and 54.7% of each group, respectively, where the left PS was open towards the SDRS laterally but sealed off from the SDRS medially. The right ARF fused with the peritoneum in all cases; and the right PS was open towards the bare area of the liver.

Conclusion:

To some extent, DSCT can display renal fascia and its superior adherence and reflect the superior communication of the PS.

Advances in knowledge:

This study was conducted in vivo in adults by high-resolution DSCT, and more samples could be provided.Retroperitoneal space is a three-dimensional space, ranging from the diaphragm to the pelvic extraperitoneal space longitudinally, between the post-parietal peritoneum and the transverse fascia of the posterior abdominal wall, with its lateral side extending to the extraperitoneal fat. The kidneys are located in the retroperitoneal space and embedded by fascia. Retroperitoneal spaces are complicated, the inside fascias divide the retroperitoneal space into different spaces. Although many researchers have studied through different methods the superior communications among these spaces there are still controversies; some scholars believed that the perirenal space (PS) opens upwards,^1–7 while others supported that the PS is upwardly closed.^8–11 Until now, most anatomical and radiological studies of the superior adherence of the renal fascia in retroperitoneal space employed the sectional anatomy on cadavers, the contrast medium injection of the cadaveric retroperitoneal space or the imaging studies based on the retroperitoneal effusion, but there were some deficiencies in such studies. In order to avoid anatomical distortion by these methods, we aimed to carry out research in vivo on adults to explore whether the renal fascias and the superior communication of the PS could be shown by high-resolution dual-source CT (DSCT) and post-processing technique, which could offer more samples at the same time. We hope that it could be helpful for anatomical positioning of diseases and analysis of their spread easily and visually, as well as the choice of treatment.     

Graft-bone healing of a meniscus autograft anchored in bone tunnels

This experiment was designed to histologically study the attachment process between a meniscus autograft and bone when the meniscus autograft is placed within bone at its anterior and posterior horns. In order to provide a time-sequenced histologic picture, a canine model was used. The study group consisted of eleven mature canines that underwent complete medial meniscectomy of the stifle joint followed by immediate replacement using an autogenous tissue meniscal scaffold fashioned from the lateral fascia of the thigh. The graft was fixed in bone tunnels at the anterior and posterior horns. One animal was sacrificed immediately after implantation, one at 10 days, three at 28 days, two at 3 months, two at 6 months, and two at nine months. Photographs were taken and histologic sections through bone tunnels were analyzed. The graft consisted of rolled tensor fascia and exogenous clot. Results: The attachment process begins with the invasion of an interface of well vascularized, primitive mesenchymal cells between the soft-tissue graft and the host bone. Histologic evidence of collagenous attachment to bone is visible at one month after graft implantation. Collagen organization with increasing soft tissue attachment to bone is progressive throughout the nine months time frame of the study. The attachment points become increasingly more continuous from three to six months. By six months, the attachment points are confluent and continuous throughout the depths of the tunnel.     

A technique for analysis of geometric mean renography

BACKGROUND AND OBJECTIVES: Renography is used routinely to assess relative right to left renal function. Quantification is usually carried out using posterior images. Errors in relative renal function may occur if the kidneys are at different depths. Geometric mean images from combined anterior and posterior views are much less affected by kidney depth and offer the opportunity of more accurate and precise quantification. Background subtraction is a key part of the analysis process and validated protocols for geometric mean imaging have not been devised. This study aims to derive a suitable background subtraction protocol for geometric mean imaging. METHODS: Simultaneous anterior and posterior renography using Tc mercaptoacetyltriglycine (MAG3) was performed on 16 adults. Analysis was carried out using both geometric mean and posterior images. The geometric mean background subtraction protocol was modified to give the same results as a posterior method, which had previously been validated by correlation with measurements of glomerular filtration rate. Absolute and relative uptakes were then obtained from both geometric mean and posterior analyses. For each analysis values were obtained both with and without depth correction. RESULTS: A revised background subtraction protocol for geometric mean renography was devised which operated successfully on all studies. Both absolute renal uptake and relative function values obtained from geometric mean analysis were not systematically different from those obtained using posterior analysis with depth correction. Values of the relative renal function from posterior analysis after depth correction were closer to the geometric mean values than estimates obtained before correction. CONCLUSION: A technique for analysing geometric mean renography data has been developed which gives results consistent with a previously validated posterior-only method.     

Ultrasound of the knee with emphasis on the detailed anatomy of anterior,medial, and lateral structures

Objective

To describe the detailed ultrasound anatomy of the anterior, medial, and lateral aspects of the knee and present the ultrasound examination technique used.

Materials and Methods

We present ultrasound using images of patients, volunteer subjects, and cadaveric specimens. We correlate ultrasound images with images of anatomical sections and dissections.

Results

The distal quadriceps tendon is made up of different laminas that can be seen with ultrasound. One to five laminas may be observed. The medial retinaculum is made up of three anatomical layers: the fascia, an intermediate layer, and the capsular layer. At the level of the medial patellofemoral ligament (MPFL) one to three layers may be observed with ultrasound. The medial supporting structures are made up of the medial collateral ligament and posterior oblique ligament. At the level of the medial collateral ligament (MCL), the superficial band, as well as the deeper meniscofemoral and meniscotibial bands can be discerned with ultrasound. The posterior part, corresponding to the posterior oblique ligament (POL), also can be visualized. Along the posteromedial aspect of the knee the semimembranosus tendon has several insertions including an anterior arm, direct arm, and oblique popliteal arm. These arms can be differentiated with ultrasound. Along the lateral aspect of the knee the iliotibial band and adjacent joint recesses can be assessed. The fibular collateral ligament is encircled by the anterior arms of the distal biceps tendon. Along the posterolateral corner, the fabellofibular, popliteofibular, and arcuate ligaments can be visualized.

Conclusion

The anatomy of the anterior, medial, and lateral supporting structures of the knee is more complex than is usually thought. Ultrasound, with its exquisite resolution, allows an accurate assessment of anatomical detail. Knowledge of detailed anatomy and a systematic technique are prerequisites for a successful ultrasound examination of the knee.     

Anatomy of the inferior extensor retinaculum and its role in lateral ankle ligament reconstruction: a pictorial essay

The inferior extensor retinaculum (IER) is an aponeurotic structure, which is in continuation with the anterior part of the sural fascia. The IER has often been used to augment the reconstruction of the lateral ankle ligaments, for instance in the Broström–Gould procedure, with good outcomes reported. However, its anatomy has not been described in detail and only a few studies are available on this structure. The presence of a non-constant oblique supero-lateral band appears to be important. This structure defines whether the augmentation of the lateral ankle ligaments reconstruction is performed using true IER or only the anterior part of the sural fascia. It is concluded that the use of this structure will have an impact on the resulting ankle stability.     

Renal fascia in urinary tract disease.

The renal fascia is rarely detected on excretory urograms. When seen, it is usually associated with disease processes such as focal renal scarring, acute renal infection, renal calculi, and intrarenal and perirenal masses. In all cases of normal appearing kidneys with visualization of the renal fascia, undetected renal disease should be suspected.