Anatomical communications of the perirenal space

Retroperitoneum revisited: a review of radiological literature and updated concept of retroperitoneal fascial anatomy with imaging features and correlating anatomy

PURPOSE

Spread of disease in the retroperitoneum is dictated by the complex anatomy of retroperitoneal fasciae and is still incompletely understood. Conflicting reports have led to insufficient and incorrect anatomical concepts in radiological literature.

METHODS

This review will discuss previous concepts prevalent in radiological literature and their shortcomings will be highlighted. New insights from recent anatomical and embryological research, together with imaging examples, will be used to clarify patterns of disease spread in the retroperitoneum that remain unexplained by these concepts.

RESULTS

The fusion fascia and the renal fascia in particular give rise to planes and spaces that act as vectors for spread of disease in the retroperitoneum. Some of these planes and structures, such as the caudal extension of the renal fascia, have previously not been described in radiological literature.

CONCLUSION

New insights, including the various fasciae, potential spaces and planes, are incorporated into an updated combined retroperitoneal fascial concept.

Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review

The retroperitoneum, a complex anatomical space within the abdominopelvic region, encompasses various vital abdominal organs. It is compartmentalized by fascial planes and contains potential spaces critical in multiple disease processes, including inflammatory effusions, hematomas, and neoplastic conditions. A comprehensive understanding of the retroperitoneum and its potential spaces is essential for radiologists in identifying and accurately describing the extent of abdominopelvic disease. This pictorial review aims to describe the anatomy of the retroperitoneum while discussing commonly encountered pathologies within this region. Through a collection of illustrative images, this review will provide radiologists with valuable insights into the retroperitoneum, facilitating their diagnostic proficiency to aid in appropriate patient clinical management.

Abdominal CT findings in Puumala hantavirus-infected patients

BACKGROUND

Previous clinical studies have reported abdominal findings on ultrasonography or MRI in Puumala hantavirus-infected patients.

PURPOSE

To determine if abdominal computed tomography (CT) can lead to a diagnosis of Puumala virus infection in the presence of a suggestive clinical picture.

MATERIAL AND METHODS

CT findings were studied retrospectively in 30 patients who presented to the emergency department of two (Belgian) hospitals with serologically confirmed Puumala hantavirus infection.

RESULTS

The most frequent finding was perirenal fascial thickening (90%), followed by perirenal fat stranding (87%). Retroperitoneal fat stranding was found in 19 patients (64%) in the perivesical spaces along the fascia of the external iliac vessels with or without involvement of the presacral fat. Half of the patients had pelvic ascites, and pleural fluid was found in 7 of them. The right and left mean pole-to-pole kidney's lengths were respectively 125.7 mm and 127.8 mm in 28 patients.

CONCLUSION

Retroperitoneal fat stranding, perirenal fascial thickening and/or perirenal fat stranding were found in most patients with acute Puumala virus infection who have undergone CT. Although nonspecific, these findings may help to suggest Puumala hantavirus infection in the right clinical settings.

Hepatocellular Carcinoma With Different Areas of Right Retroperitoneal Space Invasion: Evaluation of Transcatheter Arterial Chemoembolization Efficacy and Blood Supply Characteristics

Purpose

To evaluate the therapeutic efficacy of transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) with different areas of right retroperitoneal space (rRPS) invasion and analyze the blood supply.

Methods

This retrospective study enrolled 41 patients with HCC with different areas of rRPS invasion treated with TACE, including 22 HCCs with superior aspect of the right perirenal space (SARPS) invasion and 19 HCCs with right anterior pararenal space (RAPS) invasion. The overall response rate (ORR) and disease control rate (DCR) were analyzed. The prognostic factors for overall survival (OS) after TACE were determined. The blood supply characteristics of HCC with different areas of rRPS invasion were analyzed with arteriograms.

Results

All patients underwent 2.8 ± 1.8 TACE sessions over 25.0 ± 21.9 months. The median OS was 29.0 months for patients with SARPS invasion and 12.0 months for patients with RAPS invasion (P = 0.004). Only the invaded area of the rRPS was an independent prognostic factor for OS [hazard ratio (HR), 2.833; 95% CI, 1.297–6.188; and P = 0.009). The ORR and DCR were significantly higher in the group with SARPS invasion than in the group with RAPS invasion (ORR: 63.6% vs 31.6%, P = 0.041; DCR: 77.3% vs 47.4%, P = 0.047). Initially, HCC with SARPS invasion were supplied by the hepatic artery (HA; n = 8) and both the HA and extrahepatic collateral vessels (EHCs; n = 14); HCC with RAPS invasion were supplied by the HA (n = 10) and both the HA and EHCs (n = 9); as the TACE sessions increased, the tumor-feeding vessels shifted from the HA to both the HA and EHCs, and even EHCs could be the only blood supply. Rare EHCs appeared earlier and more frequently in the RAPS group than in the SARPS group.

Conclusion

The efficacy of TACE differed for HCC with different areas of rRPS invasion, and the median OS, ORR and DCR were significantly better in the SARPS group than in the RAPS group. Different common EHCs supplied HCCs with different areas of rRPS invasion, while other rare EHCs appeared more frequently in the RAPS group.

Understanding Retroperitoneal Anatomy for Lateral Approach Spine Surgery

Lateral approach spine surgery provides effective interbody stabilization, and correction and indirect neural decompression with minimal-incision and less invasive surgery compared with conventional open anterior lumbar fusion. It may also avoid the trauma to paraspinal muscles or facet joints found with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. However, because lateral approach surgery is fundamentally retroperitoneal approach surgery, it carries potential risk to intra- and retroperitoneal structures, as seen in a conventional open anterior approach. There is an innovative lateral approach technique that reveals different anatomical views; however, it requires reconsideration of the traditional surgical anatomy in more detail than a traditional open anterior approach. The retroperitoneum is the compartmentalized space bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. The retroperitoneum is divided into three compartments by fascial planes: anterior and posterior pararenal spaces and the perirenal space. Lateral approach surgery requires mobilization of the peritoneum and its content and accurate exposure to the posterior pararenal space. The posterior pararenal space is confined anteriorly by the posterior renal fascia, anteromedially by the lateroconal fascia, and posteriorly by the transversalis fascia. The posterior renal fascia, the lateroconal fascia or the peritoneum should be detached from the transversalis fascia and the psoas fascia to allow exposure to the posterior pararenal space. The posterior pararenal space, however, does not allow a clear view and identification of these fasciae as this relationship is variable and the medial extent of the posterior pararenal space varies among patients. Correct anatomical recognition of the retroperitoneum is essential to success in lateral approach surgery. Spine surgeons must be aware that the retroperitoneal membrane and fascia is multilayered and more complex than is commonly understood. Preoperative abdominal images would facilitate more efficient surgical considerations of retroperitoneal membrane and fascia in lateral approach surgery.

Visualization of Sliding and Deformation of Orbital Fat During Eye Rotation

Purpose

Little is known about the way orbital fat slides and/or deforms during eye movements. We compared two deformation algorithms from a sequence of MRI volumes to visualize this complex behavior.

Methods

Time-dependent deformation data were derived from motion-MRI volumes using Lucas and Kanade Optical Flow (LK3D) and nonrigid registration (B-splines) deformation algorithms. We compared how these two algorithms performed regarding sliding and deformation in three critical areas: the sclera-fat interface, how the optic nerve moves through the fat, and how the fat is squeezed out under the tendon of a relaxing rectus muscle. The efficacy was validated using identified tissue markers such as the lens and blood vessels in the fat.

Results

Fat immediately behind the eye followed eye rotation by approximately one-half. This was best visualized using the B-splines technique as it showed less ripping of tissue and less distortion. Orbital fat flowed around the optic nerve during eye rotation. In this case, LK3D provided better visualization as it allowed orbital fat tissue to split. The resolution was insufficient to visualize fat being squeezed out between tendon and sclera.

Conclusion

B-splines performs better in tracking structures such as the lens, while LK3D allows fat tissue to split as should happen as the optic nerve slides through the fat. Orbital fat follows eye rotation by one-half and flows around the optic nerve during eye rotation.

Translational Relevance

Visualizing orbital fat deformation and sliding offers the opportunity to accurately locate a region of cicatrization and permit an individualized surgical plan.

The Retroperitoneal Laparoscopic Renal Capsulectomy for Spontaneous Renal Subcapsular Fluid Collection: A Case-Series Report and Literature Review

Spontaneous renal subcapsular fluid collection may occur as a rare presentation of nephritic syndrome, and distension of the renal capsula and Gerota fascia due to massive fluid accumulation may cause pain. In addition, hypertension secondary to renal ischemia and activation of renin-angiotensin-aldosterone system may also occur. The objective of this study is to evaluate the surgical outcome of retroperitoneal laparoscopic renal capsulectomy for patients with this disease.We retrospectively analyzed the clinical data of 10 female patients with spontaneous renal subcapsular fluid collection, diagnosed with B ultrasound and enhanced computed tomography (CT) scan. Eight patients first underwent percutaneous renal subcapsular drainage, which seemed to be less effective, and then all patients underwent retroperitoneal laparoscopic renal capsulectomy. The volume of renal subcapsular fluid was documented, the fluid was examined by routine biochemical tests, and the excised renal capsules underwent pathological examination individually. The postoperative drainage time for each patient was documented, and follow-up was conducted 1, 3, 6, 12 months, and 2 years postoperatively.Retroperitoneal laparoscopic renal capsulectomy was successfully performed in all patients with no major complications. The average volume of renal subcapsular fluid was 436 milliliter (mL, 180-880 mL) in light yellow color, and the concentration of creatinine and urea nitrogen was quite similar to that of serum. The pathological findings revealed fibrous dysplasia of the renal capsule with chronic infiltration of inflammatory cells. The average drainage time was 11.5 days (5-30 days) postoperatively. All patients recovered 1 month after the operation and there were no recurrences with a mean follow-up period of 12 months (6-24 months).The reason for spontaneous renal subcapsular fluid collection is unknown, and the aim of treatment is mainly to alleviate symptoms. In our experience, retroperitoneal laparoscopic renal capsulectomy is an effective surgical treatment, especially for patients who were refractory to percutaneous renal subcapsular drainage, with no observed recurrence.

Three surgical planes identified in laparoscopic complete mesocolic excision for right-sided colon cancer

Background

Complete mesocolic excision provides a correct anatomical plane for colon cancer surgery. However, manifestation of the surgical plane during laparoscopic complete mesocolic excision versus in computed tomography images remains to be examined.

Methods

Patients who underwent laparoscopic complete mesocolic excision for right-sided colon cancer underwent an abdominal computed tomography scan. The spatial relationship of the intraoperative surgical planes were examined, and then computed tomography reconstruction methods were applied. The resulting images were analyzed.

Results

In 44 right-sided colon cancer patients, the surgical plane for laparoscopic complete mesocolic excision was found to be composed of three surgical planes that were identified by computed tomography imaging with cross-sectional multiplanar reconstruction, maximum intensity projection, and volume reconstruction. For the operations performed, the mean bleeding volume was 73 ± 32.3 ml and the mean number of harvested lymph nodes was 22 ± 9.7. The follow-up period ranged from 6–40 months (mean 21.2), and only two patients had distant metastases.

Conclusions

The laparoscopic complete mesocolic excision surgical plane for right-sided colon cancer is composed of three surgical planes. When these surgical planes were identified, laparoscopic complete mesocolic excision was a safe and effective procedure for the resection of colon cancer.

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.

The anatomical compartments and their connections as demonstrated by ectopic air

Air/gas outside the aero-digestive tract is abnormal; depending on its location, it is usually called emphysema, referring to trapped air/gas in tissues, or ectopic air/gas. It can be associated to a wide range of disorders, and although it usually is an innocuous condition, it should prompt a search for the underlying aetiology, since some of its causes impose an urgent treatment. In rare instances, it may itself represent a life-threatening condition, depending on the site involved and how quickly it evolves. Abnormal air/gas beyond viscera and serosal spaces, reaches its location following some anatomic boundaries, such as fascia, which may help search the source; however if the air pressure exceeds the strength of the tissues, or the time between the aggression and the imaging is too long, the air/gas is almost everywhere, which may hinder its cause. Good knowledge of the anatomic spaces and how they connect between them facilitates the quick detection of the cause.

Teaching points

• Ectopic air can be depicted on conventional radiographs; but CT is more sensitive and accurate

• Visceral and retropharyngeal spaces directly communicate with mediastinum

• Renal fascia is a single multilaminated structure, which contains potential space

Extraperitoneal Fluid Collection due to Chronic Pancreatitis

A 39-year-old man was referred to our hospital for the investigation of abdominal fluid collection. He was pointed out to have alcoholic chronic pancreatitis. Laboratory data showed inflammation and slightly elevated serum direct bilirubin and amylase. An abdominal computed tomography demonstrated huge fluid collection, multiple pancreatic pseudocysts and pancreatic calcification. The fluid showed a high level of amylase at 4,490 IU/l. Under the diagnosis of pancreatic ascites, endoscopic pancreatic stent insertion was attempted but was unsuccessful, so surgical treatment (Frey procedure and cystojejunostomy) was performed. During the operation, a huge amount of fluid containing bile acid (amylase at 1,474 IU/l and bilirubin at 13.5 mg/dl) was found to exist in the extraperitoneal space (over the peritoneum), but no ascites was found. His postoperative course was uneventful and he shows no recurrence of the fluid. Pancreatic ascites is thought to result from the disruption of the main pancreatic duct, the rupture of a pancreatic pseudocyst, or possibly leakage from an unknown site. In our extremely rare case, the pancreatic pseudocyst penetrated into the hepatoduodenal ligament with communication to the common bile duct, and the fluid flowed into the round ligament of the liver and next into the extraperitoneal space.

Crossing the barrier: when the diaphragm is not a limit

OBJECTIVE

The purpose of this article is to depict the anatomic pathways along which transphrenic spread of diseases and entities can disseminate.

CONCLUSION

The abdomen and thorax form a continuum on which the diaphragm is an important but incomplete barrier to disease migration.

CT evaluation of spontaneously ruptured renal angiomyolipomas with massive hemorrhage spreading into multi-retroperitoneal fascia and fascial spaces

Background

Renal angiomyolipomas (RAMLs) can spontaneously rupture and induce hemorrhage that is usually confined to the perirenal space (PS) but may spread beyond the PS into other retroperitoneal fascia and fascial spaces, including up to the subdiaphramatic and down to pelvic extra-peritoneal regions.

Purpose

To evaluate the computed tomography (CT) manifestations of renal angiomyolipoma (RAML) associated with spontaneous rupture and massive hemorrhage spreading beyond the PS into other retroperitoneal fascia and fascial spaces, including up to the subdiaphramatic and down to pelvic extra-peritoneal regions.

Material and Methods

The CT scans of seven patients with spontaneously ruptured of RAMLs and massive hemorrhage (surgically and pathologically confirmed) were retrospectively reviewed. We evaluated the CT signs of the RAML itself and the regions with extensive retroperitoneal spreading after RAML rupture.

Results

The CT manifestations of seven cases with RAML spontaneous rupture and massive hemorrhage included the following: (a) RAML signs: size (>4.0 cm, five patients; <4.0 cm, two patients), location (periphery, six patients; central portion, one patient), component (fat tissue included, seven patients), and boundary (poorly revealed, seven patients); and (b) signs of extensive retroperitoneal spreading after RAML rupture: involving the PS and extending beyond the PS (seven patients); spread to the pelvic extraperitoneal space (seven patients); attached to the subdiaphragmatic extraperitoneal region (four patients); and extended to the contralateral retroperitoneal spaces (six patients).

Conclusion

CT scans clearly depict both the primary tumor and complicated signs of a spontaneously ruptured RAML with massive hemorrhage, which can affect other fascial planes and retroperitoneal spaces and can extend upward to the subdiaphragmatic region and downward to the pelvic extraperitoneal region or communicate with the contralateral side.

Arterial blood supply to the caudate lobe of the liver from the proximal branches of the right inferior phrenic artery in patients with recurrent hepatocellular carcinoma after chemoembolization

PURPOSE

To evaluate the arterial blood supply to the caudate lobe of the liver from the proximal branches of the right inferior phrenic artery (RIPA) in patients with recurrent hepatocellular carcinoma after transcatheter arterial chemoembolization (TACE).

MATERIALS AND METHODS

Thirteen patients, including 10 who had a history of TACE of the caudate artery (A1), underwent TACE of the proximal RIPA branches. Iodized oil distribution was evaluated by computed tomography (CT) 1-week after TACE. Angiographic findings were also evaluated.

RESULTS

Previously embolized A1 was occluded (n = 15) or attenuated (n = 2). In one of three patients without A1 TACE, A1 was also attenuated. TACE was performed at the first branch of the proximal RIPA (n = 8), the first branch of the anterior branch (n = 6), and the first branch of the posterior branch (n = 1), respectively. Iodized oil was mainly distributed into the dorsal part of the Siegel lobe (SP) (n = 10), the caudate process (n = 1), and both (n = 2). In three of seven patients who had undergone serial RIPA angiography, RIPA parasitization to SP was suspected before A1 TACE.

CONCLUSION

The proximal RIPA branches mainly supply the SP when A1 is attenuated.

Visualization of the left extraperitoneal space and spatial relationships to its related spaces by the visible human project

BACKGROUND

The major hindrance to multidetector CT imaging of the left extraperitoneal space (LES), and the detailed spatial relationships to its related spaces, is that there is no obvious density difference between them. Traditional gross anatomy and thick-slice sectional anatomy imagery are also insufficient to show the anatomic features of this narrow space in three-dimensions (3D). To overcome these obstacles, we used a new method to visualize the anatomic features of the LES and its spatial associations with related spaces, in random sections and in 3D.

METHODS

In conjunction with Mimics® and Amira® software, we used thin-slice cross-sectional images of the upper abdomen, retrieved from the Chinese and American Visible Human dataset and the Chinese Virtual Human dataset, to display anatomic features of the LES and spatial relationships of the LES to its related spaces, especially the gastric bare area. The anatomic location of the LES was presented on 3D sections reconstructed from CVH2 images and CT images.

PRINCIPAL FINDINGS

What calls for special attention of our results is the LES consists of the left sub-diaphragmatic fat space and gastric bare area. The appearance of the fat pad at the cardiac notch contributes to converting the shape of the anteroexternal surface of the LES from triangular to trapezoidal. Moreover, the LES is adjacent to the lesser omentum and the hepatic bare area in the anterointernal and right rear direction, respectively.

CONCLUSION

The LES and its related spaces were imaged in 3D using visualization technique for the first time. This technique is a promising new method for exploring detailed communication relationships among other abdominal spaces, and will promote research on the dynamic extension of abdominal diseases, such as acute pancreatitis and intra-abdominal carcinomatosis.

Retrocolic Spaces: Anatomy of the Surgical Planes in Laparoscopic Right Hemicolectomy for Cancer

To explore the regional anatomy of the fasciae and spaces around the right-side colon from laparoscopic perspective, we observed the location, extension, and boundaries of the spaces around the right-side colon in seven cadavers and in 49 patients undergoing laparoscopic right hemicolectomy for cancer, and reviewed computed tomography images from patients and healthy individuals. Between the ascending mesocolon and prerenal fascia (PRF), there was a right retrocolic space (RRCS), which extended in all directions. The anterior, posterior, medial, lateral, cranial, and caudal boundaries of the RRCS were the ascending mesocolon, PRF, superior mesenteric vein, right paracolic sulcus, inferior margin of the duodenum, and inferior margin of the mesentery radix, respectively. Between the transverse mesocolon and the pancreas and duodenum, there was a transverse retrocolic space, which was enclosed cranially by the radix of the transverse mesocolon. In CT images, healthy PRF was noted as slender line of middle density, continuing to the transverse fascia. The retrocolic spaces was unidentifiable, unless they were filled with retroperitoneal lesions. The RRCS and transverse retrocolic space are natural surgical planes for laparoscopic right hemicolectomy for cancer. The boundaries of these fusion fascial spaces are the best access, and the PRF is the best guide.

Extended retroperitoneal necrotizing fasciitis with genital involvement, resembling fournier gangrene

BACKGROUND

Necrotizing fasciitis is a serious infection that originates in the subcutaneous tissues. Although many reports have been published about necrotizing infections of other anatomical sites, retroperitoneal necrotizing soft tissue infection is a rare entity that has been described in only a few case reports. The etiology and clinical course of retroperitoneal necrotizing fasciitis can be variable and it is often difficult to identify the etiology of the infective process.

CASE REPORT

We report a 58-year-old man with rapidly progressive, gas-producing, necrotizing inflammation in the retroperitoneum, complicated with genital involvement resembling Fournier gangrene. The patient was managed successfully by aggressive drainage, debridement, and sequential laparotomies to track and control the extensive necrosis of the retroperitoneum and perineum, in addition to systemic care to control sepsis. After his general condition stabilized, early rectosigmoid adenocarcinoma was identified and resected curatively. He remained well at follow up, six months after discharge.

RESULTS

In retrospect, the trigger of the disease process was unclear. Although it was believed possibly to be due to the colon lesion, adenocarcinoma of the rectosigmoid colon was identified and the patient was managed successfully.

CONCLUSIONS

Similar to necrotizing infections at other anatomical sites, early diagnosis and timely surgical intervention and systemic antimicrobial therapy are mandatory for treating patients with retroperitoneal necrotizing fasciitis.

The march of extrahepatic collaterals: analysis of blood supply to hepatocellular carcinoma located in the bare area of the liver after chemoembolization

The purpose of this study was to evaluate changes in vascular supply to hepatocellular carcinoma (HCC) located in the bare area of the liver in patients who were mainly treated with chemoembolization. Twenty-six patients with HCC showing a mean diameter of 3.1 +/- 1.4 cm (mean +/- standard deviation) were mainly treated with chemoembolization. All patients underwent 2.7 +/- 2.3 chemoembolization sessions over 40.1 +/- 25.2 months. Tumor feeding branches demonstrated in each chemoembolization session were retrospectively evaluated. Initially, 18 tumors (59.2%) were supplied by the hepatic artery (H) and 8 (30.8%) by both the hepatic and the extrahepatic arteries (H + C). Fourteen tumors (53.8%) recurred at the posterior aspect of the tumor and were supplied by H (n = 4), H + C (n = 5), and extrahepatic collaterals (C) (n = 5). Several tumors recurred despite repeated chemoembolization, and these were supplied by H (n = 1), H + C (n = 7), and C (n = 2) at the second recurrence, by H (n = 1), H + C (n = 2), and C (n = 3) at the third, by H + C (n = 2) and C (n = 2) at the fourth, by H + C (n = 2) and C (n = 2) at the fifth, and by H (n = 1) and C (n = 1) at the sixth. One tumor was supplied by H at the seventh and by H + C at the eighth recurrence. As the number of local recurrences increased, the feeding vessel shifted from H to C. Especially, the right inferior phrenic artery (IPA) and renal capsular artery (RCA) supplied the tumor early, while the small right RCAs, adrenal arteries, and intercostal and lumbar artery supplied late recurrences in turns. In conclusion, HCCs located in the bare area are frequently supplied by extrahepatic vessels initially, while recurrence after chemoembolization is mainly due to extrahepatic blood supply. The right IPA and RCA are common feeding vessels demonstrated early, while other extrahepatic collateral supply from the retroperitoneal circulation occurs in turns during the later course.

Gastric bare area and left adrenal gland involvement on abdominal computed tomography and their prognostic value in acute pancreatitis

To demonstrate the CT manifestations of gastric bare area involvement (GBAI) and left adrenal gland involvement (LAGI) in acute pancreatitis (AP) and evaluate their prognostic value. From January 2003 to December 2006, CT examinations of 116 patients with AP were retrospectively reviewed. There were 34 (29.3%) patients with GBAI showing haziness and streaky density or fluid collection in the gastric bare area, and 18 (15.5%) with LAGI showing deformity and hypoattenuation of left adrenal gland. The mean duration of hospital stay in patients with GBAI and LAGI was longer than that of patients without (P<0.001). The sensitivity and specificity of GBAI for predicting complications were 43.3% (0.31, 0.55) and 89.8% (0.81, 0.98), respectively; and 83.3% (0.36, 1.00) and 73.6% (0.65, 0.82) for predicting mortality. A patient with GBAI was 6.7 (2.4, 19.1) and 14.0 (1.6, 124.6) times more likely to have complications and die than was a patient without. The sensitivity and specificity of LAGI for predicting complications were 23.9% (0.14, 0.34) and 95.9% (0.86, 0.99), respectively, and 66.7% (0.22, 0.96) and 87.3% (0.81, 0.94) for predicting mortality. A patient with LAGI was 7.4 (1.6, 33.8) and 13.7 (2.3, 81.9) times more likely to have complications and die than was a patient without. Our results showed that GBAI and LAGI were characteristic CT findings in AP and could serve as useful prognostic indicators for this disease.

Renal-related perinephric fluid collections: MRI findings

We retrospectively reviewed MR studies on 10 patients with renal-related perinephric fluid collections who underwent MRI in three institutions between January 2001 and August 2004. All patients underwent MRI of the abdomen and T1-weighted, T2-weighted and serial contrast-enhanced images, including delayed-phase contrast-enhanced images 10-12 min after contrast injection, were obtained. Perinephric fluid collections in 5 patients revealed MRI findings of simple fluid content (i.e., hypointense on T1-weighted images and hyperintense on T2-weighted images). In another 5 patients, a complex perinephric fluid content (i.e., mixed hyper/hypointense on T1-weighted images and mixed hypo/hyperintense on T2-weighted images compatible with blood breakdown products and pus) was observed. In 5 patients, contrast extravasation on late-phase images that was compatible with urine leak was demonstrated. Our results suggest that MRI may determine the content of perinephric fluid collections on noncontrast T1-weighted and T2-weighted images and that contrast extravasation on late-phase images is associated with urine extravasation from renal collecting systems.

Multidetector row computed tomography with volume rendering--an aid to understanding pelvic anatomy and disease

Recent progress in computed tomography (CT) imaging has included multidetector row CT and volume rendering 3-dimensional post processing platforms. The growth in each of these areas has been synergistic and has offered new avenues for the formation and interpretation of diagnostic CT imaging studies. There is untapped added information in a conventional 2-dimensional axial planar pelvis study that may be harnessed with these tools. This article seeks to review the principles and application of these techniques when images of the normal pelvis are obtained. It is hoped the reader will gain insight into the design of such studies and an enhanced appreciation of the anatomic features routinely obtained on conventional CT studies.

Radiology of perinephric fluid collections

The perinephric spaces consist of the subcapsular, perirenal, anterior and posterior pararenal spaces. Fluid may collect in one or more of these compartments; this can be readily demonstrated by cross-sectional imaging, particularly computed tomography (CT). This pictorial review illustrates the radiological manifestations of perinephric fluid collections with their differential diagnosis including perinephric abscess, perirenal urine collection, subcapsular and perirenal hematoma, renal lymphangiomatosis, pancreatic pararenal fluid collections and transudate fluid associated with nephropathies.

Perirenal fluid in renal parenchymal medical disease ('floating kidney'): clinical significance and sonographic grading

AIM

To study the clinical significance and radiologic features of perirenal fluid in patients with renal parenchymal disease.

MATERIALS AND METHODS

During the previous 5 years, nine patients were found to have perirenal fluid on sonography associated with renal parenchymal medical disease. The clinical, radiological, histopathological and laboratory data were analysed.

RESULTS

The perirenal fluid is a spontaneous subcapsular transudate in patients suffering from a nephropathy with a sodium retention state, with or without renal failure. Three sonographic patterns of perirenal fluid were observed: grade 1 is a thin layer of perirenal fluid; grade 2 is a moderate amount of perirenal fluid collection with indentations of the renal parenchyma and strands in the fluid, grade 3 is a large fluid collection surrounding the kidney.

CONCLUSION

The perirenal fluid represents a sign of sodium retention state and oedema in patients with intrinsic renal parenchymal medical disease which may be caused by several nephropathies.

Helical CT evaluation of the perirenal space and its boundaries: a cadaveric study

PURPOSE

To determine whether the perirenal spaces communicate across the midline and with the pelvic extraperitoneal spaces.

MATERIALS AND METHODS

Helical CT was used to guide the sequential injection of 100-mL intravenous boluses of dilute contrast medium, up to 300 mL, into the perirenal space of eight embalmed cadavers (three male, five female; mean age at death, 82 years; range, 72-93 years), with four left-sided and four right-sided injections. All images were acquired after the final injection (300 mL total) to facilitate coronal and sagittal reconstruction of relevant images. All images were reviewed to assess the flow pathways of contrast medium from the perirenal space to other retroperitoneal spaces.

RESULTS

In three cadavers that received left perirenal space injections and in two cadavers that received right perirenal space injections, communication was seen with the contralateral perirenal space through an area anterior to the aorta and inferior vena cava. In three cadavers that received right perirenal space injections, contrast material flowed from the right perirenal space to outline the bare area of the liver. Communication between the perirenal and pelvic extraperitoneal spaces was seen in all eight cadavers; contrast material extended into the pelvic extraperitoneal and presacral spaces.

CONCLUSION

These findings show that the perirenal spaces communicate with each other across the midline and with the pelvic extraperitoneal spaces. Clinical implications are that perinephric collections can potentially flow into the pelvis or across the midline.