False-positive radiocolloid liver image due to a subphrenic abscess

A false-positive radiocolloid liver image can occur in various disease processes from extrinsic structures adjacent to the liver. A patient whose radiocolloid liver imaging showed an apparent photopenic area in the liver is presented; the abdominal CT demonstrated a low-density lesion located anterior to the liver, and at surgery the lesion was confirmed to be a right anterior subphrenic abscess.     

Splenectomy for splenic metastasis from carcinoma of colon

An 81-year-old woman with carcinoma of the colon had a normal liver-spleen radiocolloid image at the time of surgery. Two years later, a defect was noted in the spleen on a follow-up radiocolloid study. A repeat examination showed that the mass was increasing in size. An abdominal CT examination also revealed an intrasplenic mass with spring of the liver. After splenectomy for a metastatic carcinoma of the colon, the patient has survived for over a year without symptoms referable to tumor spread. Mention is made of the apparent splenic "immunity" from metastases.     

Radiocolloid liver imaging in hepatic steatosis

In a review of 60 patients with fatty infiltration of the liver documented by Xe-133 imaging, 43% had normal radiocolloid liver images, and 57% had abnormal images with various combinations of hepatomegaly, mottling, splenomegaly, and splenic shift of radioactivity. None, however, showed focal defects. Fatty infiltrates do not simulate mass lesions on the radiocolloid study of the liver, and an area of photon deficiency in the presence of hepatic steatosis points to an additional pathologic process. The interpretation of the radiocolloid liver image is unhindered by fatty infiltration when searching for discrete space-occupying lesions.     

Integrated dynamic image of the liver: a new dynamic study for evaluation of liver disease

A new method of hepatic dynamic imaging, which we designated an integrated image, is described. In this new method, the passage of the radiocolloid from the subclavian vein through the central circulation system to the abdominal organs and its accumulation in the liver was recorded on a single X-ray film. With this method, hepatic blood flow can be easily evaluated by comparison of the density between the liver and lung. Increased or decreased perfusion of the space-occupying lesions in the liver can also be evaluated. This method is very simple in technique and can be performed routinely in any hospital which has nuclear medicine facilities.     

Prominent gaseous distension of bowel causing false-positive technetium-99m sulfur colloid liver scintigram

A Tc-99m sulfur colloid liver scan carried out shortly after a prolonged upper gastrointestinal endoscopy demonstrated two concave indentations along the inferior border of the liver and increased space between the left lobe of the liver and the spleen. These abnormalities, simulating compression by an extrinsic mass, were caused by air introduced endoscopically into the gastrointestinal tract. Eight days later, a repeat radiocolloid scan was normal. There should be awareness that gaseous distension of the bowel and stomach may result in a false-positive radiocolloid liver scan. Correlation with abdominal radiographs may avert such misinterpretation.     

Detecting hepatic lesions: the added utility of CT liver window settings

PURPOSE: To prospectively evaluate the utility of adding computed tomographic (CT) liver windows to conventional soft-tissue windows for the detection of hepatic disease. MATERIALS AND METHODS: One of four radiologists experienced in abdominal imaging interpreted 1,175 consecutive abdominal CT scans from one institution. Hepatic images were first interpreted by using standard soft-tissue windows. The number of lesions and confidence in lesion detection were recorded. The liver-window images were then interpreted in conjunction with the soft-tissue-window images, and the number of lesions and confidence in detection were recorded again. The proportion of patients in whom additional lesions were found by using liver windows was determined. RESULTS: On soft-tissue-window and liver-window scans interpreted together, 869 (74%) patients had no hepatic lesions. Thirty-six (3.1%) patients had new lesions seen with the addition of liver windows. Twelve of these 36 patients had no lesions seen on soft-tissue-window scans. Twenty-six of the 36 patients with additional lesions seen had a history of neoplasm. There was a change in diagnosis in 1.7% of the patients with the addition of liver windows and a change in recommendation for follow-up in 0.85%. CONCLUSION: Routine interpretation of liver-window scans for all abdominal CT scans has limited added utility in detecting hepatic disease.     

PET/CT detects abdominal wall and port site metastases of colorectal carcinoma

Abdominal wall metastases from colorectal cancer (CRC) may be resected with curative results. Such lesions, often indicators of additional intra-abdominal lesions, may appear in surgical scars, stomas and port site metastases after laparoscope-assisted surgery (LAS). Post-operative changes, primarily surgical scars, alter local physical findings making early detection of small lesions challenging. The purpose of this study was to retrospectively evaluate the contribution of PET/CT to the diagnosis of recurrent colorectal cancer in the post-operative abdominal wall. 120 patients were referred for PET/CT with suspected recurrent CRC based on clinical, radiological or laboratory findings. All underwent whole body PET/CT imaging. 12 of these 120 (10%), were found to have abdominal wall lesions. A total of 16 abdominal wall lesions were detected, located to surgical scars, stomas, drain and laparoscope ports. Additional findings on PET/CT in this group included liver metastases, intra-abdominal lesions and retroperitoneal lymph node involvement. In general, the patients in this small group were young with high grade tumours presenting in advanced stages. In conclusion, PET/CT appears to be a sensitive tool for the diagnosis of abdominal wall recurrence of CRC. The accuracy of localization afforded by the fused functional and anatomic images makes PET/CT a likely tool for diagnosing abdominal wall lesions, including port site metastases of other aetiologies.     

Abdominal extrapancreatic lesions associated with autoimmune pancreatitis: radiological findings and changes after therapy

PURPOSE: To evaluate imaging findings of abdominal extrapancreatic lesions associated with autoimmune pancreatitis (AIP) and changes after steroid therapy. METHODS AND MATERIALS: This study included nine AIP patients with abdominal extrapancreatic lesions, which were determined by retrospective radiological review. CT (initial and follow-up, n=9) and MR imaging (initial, n=5) were reviewed by two radiologists in consensus to determine imaging characteristics (i.e., size, number, attenuation or signal intensity, and contrast enhancement of the lesions, and the presence of overlying capsule retraction) and evaluate changes with steroid therapy of abdominal extrapancreatic lesions associated with AIP. RESULTS: The most common abdominal extrapancreatic lesion associated with AIP was retroperitoneal fibrosis (RPF) in six patients. In five patients, CT and MR imaging revealed single or multiple, round- or wedge-shaped, hypoattenuating or hypointense, enhancing lesions in the renal cortex or pelvis. Other lesions included a geographic, ill-defined, hypoattenuating lesion with or without overlying capsule retraction in the liver in two and bile duct dilatation with or without bile duct wall thickening in four. Over a follow-up period of 6-81 months, CT exams of eight patients demonstrated partial or complete improvement of the abdominal extrapancreatic lesions, albeit their improvement in general lagged behind that of the pancreatic lesion. CONCLUSION: On CT or MR imaging, the abdominal extrapancreatic lesions associated with AIP are various in the retroperitoneum, liver, kidneys and bile ducts, and are reversible with steroid therapy.     

Computed tomography for the assessment of blunt abdominal trauma

Computed tomography (CT) was carried out on 70 patients with blunt abdominal trauma. Damage to the abdominal organs was clearly demonstrated by CT. The positive rates of CT in traumatic lesions were higher than those of ultrasound (US). Intraperitoneal hemorrhage was well demonstrated by US. Serum GPT levels were significantly elevated in patients with liver damage (p less than 0.001). CT proved to be useful for detecting damage to organs in patients with abdominal trauma.     

Contrast material for computed tomography and magnetic resonance imaging of the gastrointestinal tract

Various contrast agents are applied in both CT and MR imaging to improve the detection as well as the differentiation of focal liver lesions. In detecting hepatocellular carcinoma, the accuracy of Lipiodol-enhanced CT is comparable to that of CT during arterial portography. Tissue-specific contrast agents for the liver are superparamagnetic iron oxide particles, which are characterized by uptake in the reticuloendothelial system, and the paramagnetic hepatobiliary contrast agent manganese (II)-N,N'-dipyridoxylethylenediamine-N,N'-diacetate-5,5'-bis(phosphate). Both substances have the potential for markedly improving the detection of malignant liver tumors. The already good differentiation of focal hepatic lesions on plain MR images can be further improved by dynamic gadolinium diethylenetriamine penta-acetic acid-enhanced MR imaging. In the diagnosis of bile duct disorders, contrast-enhanced CT continues to be the method of choice. Water applied as a gastrointestinal contrast agent improves the staging of rectal carcinoma by CT. The development of suitable orally applied gastrointestinal contrast agents has now also improved the differentiation of the intestine from other abdominal structures on MR images, and this will lead to a general improvement of abdominal MR imaging.     

Blunt abdominal trauma: comparison of ultrasonography and computed tomography in a district general hospital

Ultrasonography has been proposed as a screening method for blunt abdominal trauma, but its specific role in comparison with other diagnostic modalities has yet to be defined. The aim of the present retrospective study was to compare the results of ultrasonography and CT of the abdomen in blunt trauma in a district general hospital. The hospital records of 25 patients who were admitted with blunt abdominal trauma to Southland Hospital, Invercargill, New Zealand, between January 1991 and November 1996 and who had both ultrasound and CT of the abdomen within 48 h of admission were reviewed. Ultrasound missed seven lesions in seven patients (7/25, 28%) compared with CT. Three of these were intestinal lesions that needed laparotomy. Ultrasound had a usefulness index of 1, 0.76, 0.72, 0.69 and 0, respectively, for detecting lesions of the kidneys, free intraperitoneal fluid, the liver, the spleen, and intestines. Although ultrasound can be used as an initial screening method for blunt abdominal trauma, CT is still the imaging modality of choice for detecting intra-abdominal lesions for stable patients in a district general hospital.     

呼吸运动对PET/CT显像诊断右上腹病灶的影响

目的探讨呼吸运动对PET／CT全身显像诊断右肺底、肝顶病灶的影响。方法回顾分析100例胸部病变患者的^18F-脱氧葡萄糖（FDG）PET／CT显像结果，观察PET、CT及两者融合图像。患者在检查时平静呼吸。观察呼吸运动伪影在不同断面的特点，对右上腹可能出现定位误差的病灶加做常规屏气CT扫描。结果①6例患者因合并胸腔、腹腔积液而未列入统计，其余38．3％（36／94例）的患者PET／CT图像有明显的呼吸运动伪影，矢状面是观察呼吸运动伪影的最佳断面：②呼吸运动致肝顶在矢状面表现为“波浪状”，横断面表现为肝脏边缘模糊，冠状面表现为突入肺底的软组织密度影。③5例患者存在右肺底、肝顶病灶，其定位可能因呼吸运动造成误差。结论呼吸运动伪影是PET／CT显像中常见的现象，对右上腹病灶定位有疑问者应加做常规屏气CT扫描。     

原发性肝癌多层面CT双动脉期与门静脉期增强扫描分析

目的：探讨原发性肝癌多层面CT（multi-slices CT,MSCT）双动脉期与门静脉期增强扫描各期强化特征及癌灶的检出率。方法：104例原发性肝癌治疗前行MSCT的平扫与三期扫描（双动脉期与门静脉期扫描）,对比剂用量100 ml,以3 ml/s的速率肘静脉注射,采集时间动脉早期20～22 s,动脉晚期34～37 s,门静脉期60 s。测病灶平扫及各增强期CT值,分析病灶的强化情况及检出情况,以增强各期检出的肿瘤数目为肿瘤灶总数。结果：三期增强扫描共显示470个病灶,34个均匀强化;436个不均匀强化,〈3 cm病灶动脉早期检出117个（56.25%）,动脉晚期检出171个（82.21%）,门静脉期检出137个（65.86%）,≥3 cm的病灶动脉早期检出237个（90.45%）,动脉晚期检出250个（95.41%）,门静脉期检出244个（93.12%）。56个仅在三期增强扫描的一期显示,动脉早期5个,动脉晚期25个,门静脉期26个。结论：动脉晚期的检出率明显高于门静脉期与动脉早期。双动脉期与门静脉期增强扫描有利于提高肝癌检出效率。     

Cat-scratch disease: report of a case with liver lesions and no lymphadenopathy

The usual presentation of cat-scratch disease (CSD) is a subacute regional lymphadenitis following cutaneous inoculation. We present the case of a 10-yr-old white female with a 4-wk history of abdominal pain and fever, without associated lymphadenopathy. A 67Ga scintigram showed inhomogenous uptake by the liver. An abdominal computed tomographic (CT) scan revealed multiple low density lesions in the liver and the spleen, that were confirmed at laparotomy. Stellate microabscesses were seen on a wedge biopsy of the liver and a CSD antigen skin test was positive. CSD should be considered in the differential diagnosis of liver lesions, even in the absence of lymphadenopathy. This case emphasizes the importance of inhomogeneous 67Ga uptake by the liver.     

胆囊穿孔的CT诊断及鉴别诊断(附12例分析)

目的 探讨胆囊穿孔的CT诊断及鉴别诊断.方法 12例经临床手术病理证实的胆囊穿孔患者的CT表现征象进行回顾性分析.结果 胆囊穿孔CT表现包括胆囊壁的改变、胆囊周围和右上腹腔的异常、肝脏内的异常密度.胆囊壁的特征性改变表现为连续性中断或局限性缺损、膨出.胆囊周围和有上腹的异常包括胆囊窝积液及右上腹包裹性积液,肌囊周围脂肪间隙密度增高或条索状影,胆囊邻近器官的改变.肝脏内异常灶表现为肝脓肿形成,胆囊与肝脓肿之间有通道.结论 螺旋CT能显示穿孔的胆囊壁连续性中断或局限性缺损,以及胆囊穿孔周围病变特征,为临床诊断和治疗提供可靠的影像学依据.     

肝脏转移性平滑肌肉瘤的CT表现

目的 分析肝脏转移性平滑肌肉瘤（metastatic liver leiomyosarcoma,MLL)的CT特点，以提高对MLL的认识。资料与方法 回顾性分析8例经手术证实的MLL的CT表现及临床特征，并复习文献。CT扫描包括平扫、动脉期、门脉期及延迟期三期增强扫描。结果 MLL平扫密度较低。较小的MLL增强后动脉期周边明显强化，中央液化坏死无强化。较大的MLL可以表现为囊性、囊实性、实性，肿瘤实质强化明显，血供丰富，血管造影证实了这一点。可有淋巴结及腹腔种植、转移。MLL易复发。结论 在肝脏占位的定性诊断中，结合原发病史、无特殊肿瘤标志物、特别是CT表现特点，应考虑到MLL的可能。     

Computer-assisted diagnosis of focal liver lesions on CT images evaluation of the Perceptron algorithm

RATIONALE AND OBJECTIVE: The purpose of the study was to investigate a modified version of a so-called Perceptron algorithm in detecting focal liver lesions on CT scans. MATERIALS AND METHODS: The modified Perceptron algorithm is based on simulated annealing with a logarithmic cooling schedule and was implemented on a standard workstation. The algorithm was trained with 400 normal and 400 pathologic CT scans of the liver. An additional 100 normal and 100 pathologic scans were then used to test the detection of pathology by the algorithm. The total of 1000 scans used in the study were selected from the portal venous phase of upper abdominal CT examinations performed in patients with normal findings or hypovascularized liver lesions. The pathologic scans contained 1 to 4 focal liver lesions. For the preliminary version of the algorithm used in this study, it was necessary to define regions of interest that were converted to a matrix of 119 x 119. RESULTS: Training of the algorithm with 400 examples each of normal and abnormal findings took about 75 hours. Subsequently, the testing took several seconds for processing each scan. The diagnostic accuracy in discriminating scans with and without focal liver lesions achieved for the 200 test scans was approximately 99%. The error rate for pathologic and normal scans was comparable to results reported in the literature, which, however, were obtained for much smaller test sets. CONCLUSION: The modified Perceptron algorithm has an accuracy of close to 99% in detecting pathology on CT scans of the liver showing either normal findings or hypovascularized focal liver lesions.     

Nodular hepatic and splenic sarcoidosis in a patient with normal chest radiograph.

Almost all the patients with sarcoidosis have an abnormal chest radiograph, while nodular lesions of both the liver and the spleen is an unusual manifestation of abdominal sarcoidosis. We report a case of a patient with numerous hypodense nodular hepato-splenic lesions on abdominal CT and a normal chest X-ray. Biopsy of an hepatic lesion revealed sarcoidosis.     

CT检查中窗技术的合理应用对提高肝内病灶检出率的意义

目的评价在传统软组织窗基础上加用肝组织窗对提高肝内病灶检出率的意义。方法接受腹部CT增强扫描的859例患者的895张顺序编号的CT片是由两位有经验的放射学医师评价的。所有的肝脏成像均采用两种窗技术进行，即起初软组织窗和随后肝组织窗。逐例记录了两种技术检出的病灶数与符合率。确定了利用肝组织窗有新增病灶的患者比例。对两种窗技术在检出病灶数方面的差异进行了统计学分析。结果在859例中，205例（24％）患者在软组织窗和肝组织窗上有肝脏病灶，其中，40例（14．6％）患者随着肝组织窗的加用，检出的病灶数亦增多。这40例中的14例患者具有在软组织窗上看不见的新增病灶。两种窗技术的病灶检出率有统计学差异（P〈0．05）。结论 单一的软组织窗不足以全部发现肝内病灶，因此，有些病灶容易漏诊，而肝组织窗的加用，可有效提高肝脏病灶的检出率与诊断准确性。     

Frequency of benign hepatic lesions incidentally detected with contrast-enhanced thin-section portal venous phase spiral CT

PURPOSE: To evaluate the frequency of benign focal hepatic lesions incidentally detected at contrast-enhanced thin-section portal venous phase spiral CT. MATERIAL AND METHODS: Between January 1998 and February 1999, contrast-enhanced hepatic spiral CT examinations were performed in 1,892 patients. Out of these, only 100 patients fulfilled the following inclusion criteria: No underlying malignant disease, no liver cirrhosis, no suspected or known focal liver lesions. Standardized spiral CT parameters were applied. All CT studies were reviewed retrospectively by one radiologist. Any focal lesion was recorded and classified. Lesion size and number were noted. RESULTS: A total of 108 hepatic lesions were reported in 33 out of 100 patients (80 cysts; 18 hemangiomas; 3 focal fatty infiltrations; 2 focal non-tumorous perfusion defects; 1 calcification; and 4 non-classified lesions). The average lesion size was 9.4 mm (< or =5 mm: n=40; 6-10 mm: n=30; 11-15 mm: n=28; >15 mm: n=10). CONCLUSION: Benign liver lesions are probably a frequent incidental finding at abdominal spiral CT.