Pediatric liver transplantation. Part II. Diagnostic imaging in postoperative management

The postoperative diagnostic imaging examinations of 44 children who underwent 59 orthotopic liver transplantations were reviewed. The imaging modalities used for the evaluation of suspected complications include plain roentgenography, ultrasonography (US), computed tomography (CT), nuclear scintigraphy, arteriography, percutaneous and operative cholangiography, and endoscopic retrograde cholangiopancreatography. The main postoperative complications included ischemia, thrombosis (hepatic artery and portal vein), infarction, obstruction or leakage of the biliary anastomosis, hepatic and perihepatic infection, and allograft rejection. US, the most frequently used abdominal imaging modality, was best suited for detection of biliary duct dilatation, fluid collections in or around the transplanted liver, and hepatic arterial, inferior vena caval, and portal vein thrombosis. CT was especially helpful in corroborating findings of infection and in locating abscesses. Technetium 99m sulfur colloid (early- and late-phase imaging) provided a sensitive, although nonspecific, means of assessing allograft vascularization and morphology. Angiography showed vascularity most clearly, and cholangiography was the most useful in the assessment of bile duct patency. A diagnostic imaging algorithm is proposed for evaluation of suspected complications.     

Liver transplantation: diagnostic imaging in the preoperative assessment]

The correct selection of patients for liver transplantation, which is essential for surgical success, requires thorough radiological evaluation. The authors present their experience on 94 pretransplant adult patients that underwent a total of 251 diagnostic exams (Doppler US, CT, angiography and cholangiography) and interventional radiology maneuvers (biopsy, chemoembolization, biliary drainage). Three sclerosing cholangitis, 3 Budd-Chiari syndromes and 20 hepatocellular carcinomas in cirrhotic patients were identified; venous collaterals were present in 62.7% of the cases, 12.8%, of which had important spontaneous porto-systemic shunts; 6 patients had portal thrombosis; 20 arterial variations were found. Interventional maneuvers were useful and free of complications. US, CT and angiographic findings of each patient were compared. Integrating informations from different exams allowed a significant increase in the accuracy of diagnostic conclusions. Thanks to interventional maneuvers 5 patients could be selected for transplantation (hepatic arterial lipiodolization stopped the growth of 4 hepatic neoplasms; 2 infected fluid collections were sterilized by percutaneous US-guided drainage and topic therapy.     

Pediatric bone imaging: diagnostic imaging of osteoid osteoma

OBJECTIVE: Osteoid osteomas are benign painful skeletal neoplasms that preferentially afflict young male patients and are readily treatable. This article focuses on the various imaging manifestations of the tumor, while also discussing its clinical presentation, pathogenesis, and treatment. CONCLUSION: Knowledge of the common imaging features of osteoid osteomas will improve our diagnosis of this condition, subsequently facilitating treatment and reducing morbidity.     

加强肝移植前后的"一站式"影像评估

肝移植是治疗终末期不可逆慢性肝脏疾病、爆发性肝功能衰竭、肝脏代谢性疾病和部分肝细胞癌的一种有效手段.随着近年来对肝脏内部解剖结构的进一步了解和显微外科技术、免疫抑制药物和影像技术的进展,肝移植在国内外的临床应用已经逐渐成熟.     

Right lobe living donor liver transplantation: preoperative evaluation of the donor with MR imaging

OBJECTIVE: The purpose of this study was to report our experience in preoperative evaluation of right hepatic lobe donors with a comprehensive MR examination and to compare abdominal MR images, MR cholangiograms, and MR angiograms with findings at surgery, intraoperative cholangiography, and digital subtraction angiography. MATERIALS AND METHODS: Twenty-eight right hepatic lobe donors underwent preoperative evaluation with MR imaging, MR cholangiography, and MR angiography. Two abdominal radiologists independently and randomly reviewed these studies. Points of assessment included focal and diffuse liver disease, calculation of right lobe volumes, depiction of the biliary tract and ductal anomalies, and depiction of the liver vasculature and vascular anomalies. Comparison was made with intraoperative cholangiograms (n = 20) and digital subtraction angiograms (n = 28). RESULTS: MR imaging revealed and characterized focal liver lesions in eight of 28 patients. Calculated right lobe volumes agreed with surgically determined volumes within 7% for reviewer 1 and within 15% for reviewer 2. Intrahepatic bile ducts were depicted completely with MR cholangiography in 25 of 28 patients and with intraoperative cholangiography in nine of 20 patients. MR cholangiography revealed ductal anomalies in six patients. MR imaging and MR angiography depicted the portal veins more completely than digital subtraction angiography. MR imaging and MR angiography correctly excluded portal venous anomalies in all patients and revealed surgically confirmed accessory hepatic veins in six of 28 patients. Angiographically confirmed arterial anomalies were correctly detected in three of 28 patients by at least one reviewer on MR imaging and MR angiography. CONCLUSION: MR imaging, MR cholangiography, and MR angiography provide a comprehensive, accurate means of evaluating donors for factors that may preclude or complicate right hepatic lobe donation.     

Accuracy of diagnostic imaging in nephroblastoma before preoperative chemotherapy

The main strategy in the treatment of nephroblastoma, as described in protocol SIOP 9/GPO, is preoperative chemotherapy for patients between 6 months and 16 years of age. Before treatment the diagnosis is made only by diagnostic imaging without biopsy. From July 1988 to February 1991, 130 children with the tentative diagnosis of nephroblastoma were treated preoperatively. The initial diagnostic images (excretory urography, ultrasound, CT, MRI) have been analysed both prospectively and retrosperatively and the findings correlated with the intraoperative and histological results. Of the preoperatively treated patients 93.8% had a Wilms' tumour or one of its variants. Five patients had a different malignant tumour and 3 patients, i.e. 2.3% of those preoperatively treated or 1.6% of all registered patients, had benign tumours of the kidney. Wilms' tumour generally presented as a well-defined mass with an inhomogeneous morphology on CT. On ultrasound only 24% of the tumours were homogeneous. Intratumoral haemorrhage and cystic areas occurred frequently; calcifications were rare (8%). With regard to caval involvement only ultrasound and MRI enabled the correct diagnosis, while CT could not differentiate compressions from invasion. The pretherapeutic diagnostic imaging was of sufficient accuracy to start preoperative chemotherapy without diagnostic biopsy.Correspondence to: K. Rieden     

Use of imaging for living donor liver transplantation.

Living donor liver transplantation is emerging as an alternative to cadaveric liver transplantation. The authors present multimodality images obtained in 44 cases of living donor liver transplantation. The images in this article were derived from the pre-, intra-, and postoperative imaging protocol for their institutional transplantation program. Preoperative magnetic resonance (MR) imaging in the donor allows detection of focal liver lesions and accurate determination of liver volume. The latter is crucial to ensure adequate postoperative liver function for donors and recipients. MR cholangiography depicts donor biliary anatomy. MR angiography and digital subtraction arteriography are performed to assess vascular anatomy. Intraoperative ultrasonography (US) helps determine the resection plane during donor hepatectomy. Postoperative MR imaging documents liver regrowth. MR imaging, US, and computed tomography help assess complications in donors and recipients.     

Inaccurate preoperative imaging assessment on biliary anatomy not increases biliary complications after living donor liver transplantation

Backgrounds and aims

Accurate assessment of graft bile duct is important to plan surgical procedure. Magnetic resonance cholangiopancreatography (MRCP) has become an important diagnostic procedure in evaluation of pancreaticobiliary ductal abnormalities and has been reported as highly accurate. We aim to estimate the efficacy of preoperative MRCP on depicting biliary anatomy in living donor liver transplantation (LDLT), and to determine whether inaccurate preoperative imaging assessment would increase the biliary complications after LDLT.

Methods

The data of 118 cases LDLT were recorded. Information from preoperative MRCP was assessed using intraoperative cholangiography (IOC) as the gold standard. The possible risk factors of recipient biliary complications were analyzed.

Results

Of 118 donors, 84 had normal anatomy (type A) and 34 had anatomic variants (19 cases of type B, 9 cases of type C, 1 case of type E, 2 cases of type F and 3 cases of type I) confirmed by IOC. MRCP correctly predicted all 84 normal cases and 17 of 34 variant cases, and showed an accuracy of 85.6% (101/118). The incidence of biliary complications was comparable between cases with accurate and inaccurate classification of biliary tree from MRCP, and between cases with normal and variant anatomy of bile duct. While cases with graft duct opening ≤5 mm showed a significant higher incidence of total biliary complications (21.1% vs. 6.6%, P = 0.028) and biliary stricture (10.5% vs. 1.6%, P = 0.041) compared with cases with large duct opening >5 mm.

Conclusion

MRCP could correctly predict normal but not variant biliary anatomy. Inaccurate assessment of biliary anatomy from MRCP not increases the rate of biliary complications, while small-sized graft duct may cause an increase in biliary complications particularly biliary stricture after LDLT.     

MR imaging of the knee. Part I. Traumatic disorders

One hundred thirty patients with a diversity of knee joint injuries were evaluated with a high-resolution magnetic resonance (MR) imaging technique. The authors report the accuracy of this technique in the evaluation of 105 patients with suspected meniscal tears, 26 patients with suspected cruciate ligament tears, and eight patients with suspected patellar tendon injuries. Of those menisci rated as definitely or probably torn on MR imaging, 80% were found to be torn at subsequent arthroscopy. The predictive value of negative MR imaging results was 100%. MR imaging was 92% accurate in predicting the clinical outcome in patients with suspected meniscal tears who did not undergo surgery. MR permitted complete disruption of the patellar tendon to be differentiated from partial tears, ligamentous inflammation, and localized effusion of the infrapatellar bursa. Injuries to the anterior and posterior cruciate ligaments were identified on MR images, and the status of synthetic grafts of the anterior cruciate ligament was ascertained.     

Multimodality postoperative imaging of liver transplantation

Liver transplantation is the only effective and definitive treatment for patients with end-stage liver disease. The shortage of cadaveric livers has lead to the increasing use of split-liver transplantation and living-donor liver transplantation, but the expansion of the donor pool has increased the risk for postoperative vascular and biliary complications. Early recognition of the imaging appearances of the various postoperative complications of liver transplantation is crucial for both graft and patient survival. This review describes the imaging findings of normal and abnormal transplanted liver parenchyma and of vascular and biliary post-transplantation complications.     

Living related liver transplantation: preoperative magnetic resonance imaging for assessment of hepatic vasculature of donor candidates

Purpose: To evaluate the accuracy of magnetic resonance angiography (MRA) for preoperative assessment of hepatic vascular anatomy in liver donors before living related liver transplantation.

Material and Methods: A total of 55 consecutive living liver donors (mean age 42 years, range 18-68 years) underwent multiphase contrast-enhanced MRA of the hepatic vessels. Two readers categorized vessel visualization on a five-point scale and recorded vascular anatomy or variations thereof for the arterial, portal venous and venous systems. All 55 living liver donors subsequently underwent right hemihepatectomy for hemiliver donation, and preoperative MRA results were correlated with surgical findings.

Results: Overall vessel visualization assessment demonstrated good or very good ratings for the majority of patients. For hepatic arteries, the mean score was 4.4±0.8 (mean±standard deviation), and for the portal venous and venous systems it was 4.6±0.7 and 4.3±0.8, respectively. Among all 55 donors, 16 (29%) demonstrated accessory or replaced hepatic arteries, and seven (13%) and 20 (36%) donors had surgically relevant portal vein (trifurcation or early right posterolateral branching types) and hepatic vein variations, respectively. Correlation coefficients between MRA and surgery were 0.94, 1.00 and 0.91 for hepatic arteries, portal veins and hepatic veins, respectively.

Conclusion: In the preoperative evaluation before living related liver donation, contrast-enhanced MR angiography was a highly accurate, noninvasive tool for visualizing the hepatic vasculature and variations thereof in liver donor candidates.     

Non-invasive diagnostic imaging of colorectal liver metastases

Colorectal cancer is one of the few malignant tumors in which synchronous or metachronous liver metastases [colorectal liver metastases (CRLMs)] may be treated with surgery. It has been demonstrated that resection of CRLMs improves the long-term prognosis. On the other hand, patients with un-resectable CRLMs may benefit from chemotherapy alone or in addition to liver-directed therapies. The choice of the most appropriate therapeutic management of CRLMs depends mostly on the diagnostic imaging. Nowadays, multiple non-invasive imaging modalities are available and those have a pivotal role in the workup of patients with CRLMs. Although extensive research has been performed with regards to the diagnostic performance of ultrasonography, computed tomography, positron emission tomography and magnetic resonance for the detection of CRLMs, the optimal imaging strategies for staging and follow up are still to be established. This largely due to the progressive technological and pharmacological advances which are constantly improving the accuracy of each imaging modality. This review describes the non-invasive imaging approaches of CRLMs reporting the technical features, the clinical indications, the advantages and the potential limitations of each modality, as well as including some information on the development of new imaging modalities, the role of new contrast media and the feasibility of using parametric image analysis as diagnostic marker of presence of CRLMs.     

Staging of colorectal liver metastases after preoperative chemotherapy. Diffusion-weighted imaging in combination with Gd-EOB-DTPA MRI sequences increases sensitivity and diagnostic accuracy

Objectives

To compare the diagnostic accuracy and sensitivity of Gd-EOB-DTPA MRI and diffusion-weighted (DWI) imaging alone and in combination for detecting colorectal liver metastases in patients who had undergone preoperative chemotherapy.

Methods

Thirty-two consecutive patients with a total of 166 liver lesions were retrospectively enrolled. Of the lesions, 144 (86.8 %) were metastatic at pathology. Three image sets (1, Gd-EOB-DTPA; 2, DWI; 3, combined Gd-EOB-DTPA and DWI) were independently reviewed by two observers. Statistical analysis was performed on a per-lesion basis.

Results

Evaluation of image set 1 correctly identified 127/166 lesions (accuracy 76.5 %; 95 % CI 69.3–82.7) and 106/144 metastases (sensitivity 73.6 %, 95 % CI 65.6–80.6). Evaluation of image set 2 correctly identified 108/166 (accuracy 65.1 %, 95 % CI 57.3–72.3) and 87/144 metastases (sensitivity of 60.4 %, 95 % CI 51.9–68.5). Evaluation of image set 3 correctly identified 148/166 (accuracy 89.2 %, 95 % CI 83.4–93.4) and 131/144 metastases (sensitivity 91 %, 95 % CI 85.1–95.1). Differences were statistically significant (P?<?0.001). Notably, similar results were obtained analysing only small lesions (<1 cm).

Conclusions

The combination of DWI with Gd-EOB-DTPA-enhanced MRI imaging significantly increases the diagnostic accuracy and sensitivity in patients with colorectal liver metastases treated with preoperative chemotherapy, and it is particularly effective in the detection of small lesions.

Key Points

? Accurate detection of colorectal liver metastases is essential to determine resectability. ? Almost 80 % of patients are candidates for neoadjuvant chemotherapic treatment at diagnosis. After chemotherapy, metastases usually decrease, and drug-induced liver steatosis may be present. ? The sensitivity of imaging is significantly inferior to that in chemotherapy-naïve patients. ? DWI combined with Gd-EOB-DTPA increases sensitivity in detecting small metastases after chemotherapy.     

Neck neoplasms: MR imaging. Part I. Initial evaluation

Untreated neoplasms of the neck (tumors of the oropharynx, supraglottic area, carotid body, and thyroid, in addition to malignant lymphadenopathy) were evaluated in 23 patients with magnetic resonance (MR) imaging. The results were compared with computed tomographic (CT) scans in 20 patients. Contrast between tumor and fat was best on relatively T1-weighted images (500/30-35 [TR msec/TE msec]), whereas separation of tumor and muscle was best with relatively T2-weighted pulse sequences (1,500/90). Balanced images (1,500/30-35) provided best overall image quality and best demonstrated vascular anatomy. MR imaging was usually superior to CT in showing the relationship of tumor mass to muscle. MR imaging and contrast material-enhanced CT were equivalent in most patients in defining vascular anatomy, but MR imaging was superior when intravenous contrast material was not administered. However, CT was more helpful in showing bone and cartilage anatomy, and in some patients CT also was better in showing airway abnormalities. Despite these limitations, MR imaging is a promising imaging technique for studying neoplasms of the neck.     

Carpal tunnel: MR imaging. Part I. Normal anatomy

To correlate the important structures of the carpal tunnel demonstrated on magnetic resonance (MR) images with gross anatomy, the authors imaged the wrists of 20 normal volunteers and nine cadavers. The cadaver specimens were sectioned in the same planes in which they were imaged, and three other specimens were dissected. The anatomy was directly correlated with the imaged morphology. Axial images delineated well the bone and ligament walls of the carpal tunnel. The median nerve was well delimited and of moderate signal intensity. It was surrounded in some cases by fat but was consistently bound by specific tendons. The ulnar nerve and artery were visualized as they traversed the Guyon canal to their division into superficial and deep branches. Coronal images permitted optimal visualization of the triangular fibrocartilage and the radial and ulnar collateral ligaments. Quantitative studies indicated that the normal median nerve does not significantly increase in size within the carpal tunnel but does become more flattened at the level of the pisiform bone. The normal flexor retinaculum may have a slight palmar bowing.