Small hepatocellular carcinomas in chronic liver disease: detection with SPECT

Single-photon emission computed tomography (SPECT) performed using a rotating gamma camera was compared with alpha 1-fetoprotein (AFP) assay, conventional liver scintigraphy, ultrasound (US) imaging, computed tomography (CT), and selective celiac angiography in 40 patients with a total of 50 small hepatocellular carcinomas (HCCs; less than 5 cm). The detection rates of US and CT were determined on an initial screening study and on a second, more precisely focused study. The detection rate of small HCCs by the various modalities was as follows: AFP, 13%; liver scintigraphy, 36%; SPECT, 72%; initial screening US, 80%; second, more precise US studies, 94%; initial screening CT, 64%; second, more precise CT study, 82%; angiography, 88%. Although SPECT was inferior to the initial screening US examination in detecting HCCs less than 2 cm in size, its sensitivity was identical to that of the initial screening US study for detecting HCCs of 2-5 cm. The combination of SPECT and US was an excellent method for the early detection of HCCs, yielding a detection rate of 94%.     

Single photon emission computed tomography (SPECT), planar scintigraphy, and transmission computed tomography: a comparison of accuracy in diagnosing focal hepatic disease

A prospective evaluation of conventional planar scintigraphy (PS), single photon emission computed tomography (SPECT), and transmission computed tomography (TCT) was performed in 98 patients with suspected focal hepatic disease (FHD). The three examinations were performed on the same day. TCT had slightly higher sensitivity (91%) and specificity (96%) than either PS or SPECT. The sensitivity and specificity of TCT was also higher than that of the combination of PS and SPECT, which was more accurate than either radionuclide technique alone, with a sensitivity of 85-87% and a specificity of 90%. These differences were not statistically significant. However, receiver operating characteristic (ROC) analysis showed that the performance of TCT was significantly better. The ROC curves also showed, without statistical significance, that SPECT appears to have better diagnostic accuracy than PS and that it seems desirable to complement SPECT imaging with PS views, to reduce the number of equivocal results.     

Hepatobiliary manifestations of cystic fibrosis in children: correlation of CT and US findings.

MATERIAL AND METHODS: Abdominal US and CT scans of 50 pediatric cystic fibrosis (CF) patients were evaluated to search for specific data that can be attributed to the involvement of the hepatobiliary system. The liver findings of the two patients who were HBs antigen carriers were excluded from the study. RESULTS: 30 out of 48 patients had at least one abnormal finding of liver on CT and/or US. Although increased echogenicity of the liver was detected in 24 of 48 patients (50%), only six of these (12%) were regarded as steatosis according to CT criteria of low attenuation values. CT and US scans both showed unique multilobular fatty pattern, described as "pseudomasses" in three patients. Increased periportal echogenicity was seen in 18 (37%) patients on US, while CT could not demonstrate any sign of increased periportal thickness. Findings of cirrhosis were present in five patients with either modalities. Lymph nodes of less than 10-15 mm in diameter were detected at the hepatico-duodenal ligament in 18 (37%) patients. Anomalies of the gallbladder (absence or microgallbladder or stone) were detected in 12 cases (24%). CONCLUSION: Although US is the most widely used modality in CF patients, CT and US correlation will help to better delineate the abnormalities between steatosis and periportal fibrosis and increase the sensitivity of the imaging methods to achieve the most accurate diagnosis.     

Improved detection of small cavernous hemangiomas of the liver with high-resolution three-headed SPECT.

The purpose of this study was to review our experience with 99mTc-red blood cell scintigraphy for diagnosis of cavernous hemangiomas of the liver using a new three-headed, high-resolution dedicated SPECT system. Of 19 patients referred with a total of 38 lesions seen on CT, US, or MRI, 14 patients had 24 lesions that were hemangioma-positive with SPECT (all true-positives). Six of these 14 patients also had 9 hemangioma-negative lesions; all were less than or equal to 1.3 cm in size and false-negative. The remaining five patients had hemangioma-negative lesions only (1 false-negative, 4 true-negatives). Two hemangiomas were seen by SPECT that were not detected by CT, US, or MR. The sensitivity for hemangiomas greater than or equal to 1.4 cm. was 100% (20/20). The sensitivity was 33% for lesions 0.9-1.3 cm, and 20% for lesions less than or equal to 0.8 cm. The smallest hemangioma detected was 0.5 cm. These results show a definite improvement in sensitivity with high-resolution triple-headed SPECT over previously reported results using single-headed SPECT. High-resolution SPECT has improved our ability to detect small cavernous hemangiomas of the liver.     

Density histogram analysis of unenhanced hepatic computed tomography in patients with diffuse liver diseases

OBJECTIVE: The aim of the study was to assess the potential of density histogram analysis of unenhanced hepatic computed tomography (CT) in the diagnosis and differentiation of diffuse liver diseases. METHODS: Twenty-six patients with normal liver parenchyma, 35 patients with diffuse steatosis, 14 patients with acute steatohepatitis, 15 patients with active alcoholic cirrhosis, 23 patients with inactive alcoholic cirrhosis, 15 patients with virus-induced cirrhosis, and 8 patients with hemochromatosis underwent unenhanced hepatic CT. All diffuse liver diseases and the absence of diffuse liver disease were histologically proven. Quantitative analysis of unenhanced liver parenchyma was performed in each patient. RESULTS: The hepatic density histogram showed no significant differences in kurtosis and skewness between the groups (P > 0.05). Except for steatosis, active alcoholic cirrhosis, and hemochromatosis, diffuse liver diseases led to similar densities of liver parenchyma in unenhanced hepatic CT. CONCLUSION: A reliable diagnosis and differentiation of diffuse liver diseases on the basis of density histogram analysis is not possible.     

Effectiveness of quantitative MAA SPECT/CT for the definition of vascularized hepatic volume and dosimetric approach: phantom validation and clinical preliminary results in patients with complex hepatic vascularization treated with yttrium-90-labeled microspheres

The goal of this study was to assess the use of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) analysis for vascularized volume measurements in the use of the yttrium-90-radiolabeled microspheres (TheraSphere). A phantom study was conducted for the validation of SPECT/CT volume measurement. SPECT/CT quantitative analysis was used for the measurement of the volume of distribution of the albumin macroaggregates (MAA; i.e., the vascularized volume) in the liver and the tumor, and the total activity contained in the liver and the tumor in four consecutive patients presenting with a complex liver vascularization referred for a treatment with TheraSphere. SPECT/CT volume measurement proved to be accurate (mean error <7%) and reproducible (interobserver concordance 0.99). For eight treatments, in cases of complex hepatic vascularization, the hepatic volumes based on angiography and CT led to a relative overestimation or underestimation of the vascularized hepatic volume by 43.2 ± 32.7% (5-87%) compared with SPECT/CT analyses. The vascularized liver volume taken into account calculated from SPECT/CT data, instead of angiography and CT data, results in modifying the activity injected for three treatments of eight. Moreover, quantitative analysis of SPECT/CT allows us to calculate the absorbed dose in the tumor and in the healthy liver, leading to doubling of the injected activity for one treatment of eight. MAA SPECT/CT is accurate for volume measurements. It provides a valuable contribution to the therapeutic planning of patients presenting with complex hepatic vascularization, in particular for calculating the vascularized liver volume, the activity to be injected and the absorbed doses. Studies should be conducted to assess the role of quantitative MAA/SPECT CT in therapeutic planning.     

Performance of orthopantomography, planar scintigraphy, CT alone and SPECT/CT in patients with suspected osteomyelitis of the jaw

Purpose

The aim of this study was to evaluate the performance of a novel flat-panel single photon emission computed tomography (SPECT)/CT in patients with suspicion of osteomyelitis (OM) of the jaw in comparison with conventional orthopantomography (OPT), planar bone scintigraphy (PS) and CT alone.

Methods

Forty-two patients (21 female, 21 male, mean age 52, range 10–84 years) with suspected OM (n?=?38) or exacerbation of a known OM (n?=?4) were investigated with OPT, CT alone, PS and combined SPECT/CT. Images were separately reviewed by a nuclear physician/radiologist and jaw surgeon regarding presence of OM. Additionally, the different methods were rated regarding their usefulness for diagnosis (5-point scale: from 1 = diagnostic to 5 = useless). Biopsy served as the standard of reference in 30 patients and clinical/imaging follow-up of at least 6 months in 12 patients.

Results

In 35 of 42 patients the final diagnosis of OM was established according to the reference standard. Sensitivity, specificity and accuracy for OPT was 59, 100 and 66 %, for CT alone 77, 86 and 79 %, for PS 100, 71 and 95 % and for SPECT/CT 100, 86 and 98 %. SPECT/CT was significantly more accurate compared with CT alone (p?=?0.0078) and OPT (p?=?0.001). SPECT/CT was rated as the most useful imaging modality (mean value 1.2) compared with PS (2.2), CT (2.5) and OPT (3.2).

Conclusion

SPECT/CT is an accurate method to assess the presence of OM of the jaw and superior to CT alone and OPT. SPECT/CT slightly improved the specificity of PS. However, SPECT/CT in this study was not significantly more accurate compared with PS and whether the advantages to the patient of a one-stop study as opposed to doing separate CT and PS justifies its routine use in terms of cost requires further study.     

Quantitative Assessment of Liver Fat with Magnetic Resonance Imaging and Spectroscopy

Hepatic steatosis is characterized by abnormal and excessive accumulation of lipids within hepatocytes. It is an important feature of diffuse liver disease, and the histological hallmark of non-alcoholic fatty liver disease (NAFLD). Other conditions associated with steatosis include alcoholic liver disease, viral hepatitis, HIV and genetic lipodystrophies, cystic fibrosis liver disease, and hepatotoxicity from various therapeutic agents. Liver biopsy, the current clinical gold standard for assessment of liver fat, is invasive and has sampling errors, and is not optimal for screening, monitoring, clinical decision making, or well-suited for many types of research studies. Non-invasive methods that accurately and objectively quantify liver fat are needed. Ultrasound (US) and computed tomography (CT) can be used to assess liver fat but have limited accuracy as well as other limitations. Magnetic resonance (MR) techniques can decompose the liver signal into its fat and water signal components and therefore assess liver fat more directly than CT or US. Most magnetic resonance (MR) techniques measure the signal fat-fraction (the fraction of the liver MR signal attributable to liver fat), which may be confounded by numerous technical and biological factors and may not reliably reflect fat content. By addressing the factors that confound the signal fat-fraction, advanced MR techniques measure the proton density fat-fraction (the fraction of the liver proton density attributable to liver fat), which is a fundamental tissue property and a direct measure of liver fat content. These advanced techniques show promise for accurate fat quantification and are likely to be commercially available soon.     

符合线路SPECT在消化系统肿瘤术后复发转移中的应用研究

探讨18F-FDG符合线路SPECT在消化系统肿瘤术后复发转移中的临床应用价值.材料和方法:对35例临床怀疑复发转移的消化系统肿瘤术后患者行18F-FDG符合线路SPECT显像,对其显像结果进行分析,计算其诊断的准确率、灵敏度、特异性、阳性预测值、阴性预测值及其95%可信区间,并与B超、CT、MRI的诊断结果相比较.结果:在35例消化系统肿瘤术后患者中,其诊断的准确率、灵敏度、特异性、阳性预测值、阴性预测值分别为91.4%、88.9%、100%、100%、72.7%;其95%可信区间分别为77%～98%、71%～98%、63%～100%、86%～100%、39%～94%.符合线路SPECT的诊断准确率、灵敏度明显高于B超,与CT和MRI的比较尚无显著性差异;95%可信区间分析,结果显示符合线路SPECT高于B超、CT和MRI;18F-FDG符合线路SPECT和B超、CT、MRI联合应用在某些病例的诊断中具有互补性.结论:18F-FDG SPECT/PET显像在消化系统肿瘤术后复发转移的诊断中具有较高的临床应用价值.     

Macrovesicular hepatic steatosis in living liver donors: use of CT for quantitative and qualitative assessment

PURPOSE: To determine prospectively the diagnostic performance of unenhanced computed tomography (CT) in the assessment of macrovesicular steatosis in potential donors for living donor liver transplantation by using same-day biopsy as a reference standard. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. A total of 154 candidates, including 104 men (mean age, 30.2 years +/- 10.3 [standard deviation]) and 50 women (mean age, 31.8 years +/- 11.2), underwent same-day unenhanced CT and ultrasonography-guided liver biopsy. Histologic degree of macrovesicular steatosis was determined. Three liver attenuation indices were derived: liver-to-spleen attenuation ratio (CT(L)(/S)), difference between hepatic and splenic attenuation (CT(L)(-S)), and blood-free hepatic parenchymal attenuation (CT(LP)). Regression equations were used to quantitatively estimate the degree of macrovesicular steatosis. Limits of agreement between estimated macrovesicular steatosis and the reference standard were calculated. Receiver operating characteristic analyses were used to determine the performance of each index for qualitative diagnosis of macrovesicular steatosis of 30% or greater. The cutoff value that provided a balance between sensitivity and specificity and the highest cutoff value that yielded 100% specificity were determined. RESULTS: Limits of agreement were -14% to 14% for CT(L)(/S) and CT(L)(-S) and -13% to 13% for CT(LP). Performance in diagnosing macrovesicular steatosis of 30% or greater was not significantly different among indices (P > .05). Cutoff values of 0.9, -7, and 58 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and provided a balance between sensitivity and specificity. Cutoff values of 0.8, -9, and 42 were determined for CT(L)(/S), CT(L)(-S), and CT(LP), respectively, and yielded 100% specificity for all indices, with corresponding sensitivities of 82%, 82%, and 73% for CT(L)(/S), CT(L)(-S), and CT(LP), respectively. CONCLUSION: Diagnostic performance of unenhanced CT for quantitative assessment of macrovesicular steatosis is not clinically acceptable. Unenhanced CT, however, provides high performance in qualitative diagnosis of macrovesicular steatosis of 30% or greater.     

Liver scintigraphy in a patient with Gaucher disease

Liver scintigraphy including SPECT was performed in a patient with Gaucher disease and compared with other methods. Multiple photon-deficient areas in the liver and spleen were recognized, and in evaluating the reticuloendothelial system of the liver, liver SPECT image was superior to US, CT and MR images.     

Technetium-99m-labelled red blood cell imaging in the diagnosis of hepatic haemangiomas: the role of SPECT/CT with a hybrid camera

Delayed liver single-photon emission computed tomography (SPECT) after ^99mTc red blood cell (RBC) labelling is helpful in detecting hepatic haemangiomas; however, diagnosis can be difficult when lesions are situated adjacent to structures like the inferior vena cava, the heart or hepatic vessels, where blood activity persists. The aims of this study were to evaluate the usefulness of RBC SPECT and transmission computed tomography (RBC SPECT/CT) performed simultaneously with a hybrid imaging system for correct characterisation of hepatic lesions in patients with suspected haemangioma, and to assess the additional value of fused images compared with SPECT alone. Twelve patients with 24 liver lesions were studied. The acquisitions of both anatomical (CT) and functional (SPECT) data were performed during a single session. SPECT images were first interpreted alone and then re-evaluated after adding the transmission anatomical maps. Image fusion was successful in all patients, with perfect correspondence between SPECT and CT data, allowing the precise anatomical localisation of sites of increased blood pool activity. SPECT/CT had a significant impact on results in four patients (33.3%) with four lesions defined as indeterminate on SPECT images, accurately characterising the hot spot foci located near vascular structures. In conclusion, RBC SPECT/CT imaging using this hybrid SPECT/CT system is feasible and useful in the identification or exclusion of suspected hepatic haemangiomas located near regions with high vascular activity.     

SPECT versus planar liver scintigraphy: is SPECT worth it?

Five hundred three planar and SPECT hepatic studies were reviewed separately by two experienced observers looking for focal disease. An equivocal reading meant referral to ultrasound or computed tomography (US/CT). The increase in correct readings and decrease in US/CT referrals per 100 positive and per 100 negative SPECT readings were calculated, then the increase in correct readings and decrease in US/CT referrals for various positive rates of liver involvement determined. At our institution, the overall positive rate is approximately 13% yielding 1.1 and 0.83 more correct readings and 1.8 and 2.0 fewer US/CT referrals per 100 cases for each reader, respectively; a marginal benefit for SPECT over planar scintigraphy.     

Evaluation of combined transmission and emission tomography for classification of skeletal lesions

OBJECTIVE: This study assessed the benefit of transmission emission tomography (TET) for classification of skeletal lesions in patients with known malignant disease. SUBJECTS AND METHODS: The TET technology combines acquisition of SPECT and CT data using the same imaging device, thus allowing perfect overlay of anatomic and functional images. We performed TET in 47 patients with tumors who had a total of 104 focal lesions found on bone scintigraphy. Technetium-99m diphosphonate was used as the radiopharmaceutical in all patients. Findings of bone scintigraphy (planar and SPECT), SPECT + CT or radiography, and TET were compared with regard to the precise location and nature (benign vs malignant) of each lesion. Validation was achieved by radiologic follow-up on CT, MRI, or radiography, especially for the extremities, and using biopsy results in five patients. RESULTS: TET could classify 88 (85%) of 104 lesions compared with 37 (36%) of 104 on SPECT. When we counted inconclusive studies as positive for cancer, discrepant findings between SPECT and TET were obtained in 39 lesions. In 38 (97%) of these, TET was correct. Sensitivity for cancer detection was 98% for TET and 94% for SPECT (p = 0.63), and specificity was 81% for TET and 19% for SPECT (p < 0.0001). The highest diagnostic gain was in the spine, thoracic cage, skull, and pelvis. Small osteolytic lesions were missed because of the limited resolution of transmission images. SPECT + CT or radiography and TET were discordant in nine of 104 lesions. TET was false-negative in one lesion and false-positive in another, and SPECT + CT or radiography was false-positive in seven lesions. As a result, sensitivities of TET and SPECT + CT or radiography were nearly the same, but the specificity of TET was significantly higher (p = 0.015). CONCLUSION: TET improves the accuracy of bone scintigraphy by correctly classifying equivocal lesions, especially by identifying benign abnormalities in the axial skeleton and thus increasing the specificity of positive findings.     

Computed tomography features of nonalcoholic steatohepatitis with histopathologic correlation

OBJECTIVE: This study was conducted to describe the computed tomography (CT) features of nonalcoholic steatohepatitis (NASH) and to evaluate if the CT features could be used to diagnose and stage NASH. METHODS: From 1994 until 2004, pathology records revealed 68 patients with NASH. Of these, 12 patients underwent CT scans before (n=6), on the same day as (n=3), or after (n=3) a liver biopsy. Using the same database, 9 patients with steatosis alone evaluated with a CT scan before (n=2), on the same day as (n=3), or after (n=4) the liver biopsy were selected as a control group. Two radiologists measured liver attenuation (compared with spleen) and assessed the pattern of steatosis, craniocaudal liver span, caudate-to-right lobe ratio, preportal space distance, and presence of porta hepatis lymph nodes and ascites. Biopsy specimens were assessed by a pathologist, and the degree of necroinflammatory activity, steatosis, and fibrosis was determined. Histopathologic and CT findings were compared between patients with NASH and patients with steatosis alone using the Mann-Whitney U test and Fisher exact test. RESULTS: In patients with NASH, the mean liver-to-spleen attenuation ratio was 0.66 (range: 0.1-1.1). Steatosis was diffuse (n=9), geographic or nonlobar (n=2), or diffuse with an area of focal sparing (n=1). The liver craniocaudal span varied from 17.5 to 25.5 cm (mean=21.4 cm), and hepatomegaly was present in 11 (91.7%) patients. The caudate-to-right-lobe ratio (mean=0.43) and preportal space (mean=4.5 mm) were normal in all cases. Porta hepatis lymph nodes were present in 7 (58.3%) patients; their mean dimensions were 16 mmx11 mm. Ascites was absent in all patients. On histopathology, the degree of necroinflammatory activity was mild (n=9), moderate (n=1), or severe (n=2). The degree of steatosis was 33% to 66% (n=5) or >67% (n=7). All but 3 patients had fibrosis; 6 had focal nonbridging fibrosis, 1 had multifocal nonbridging fibrosis, and 2 had bridging fibrosis. There was a significant correlation between the degree of steatosis on pathologic examination and the liver-to-spleen attenuation ratio on CT (P=0.048). The severity of inflammation and stage of fibrosis on pathologic examination did not correlate with the CT features. Among patients with steatosis alone, the mean liver-to-spleen attenuation ratio was 0.80 (range: 0.3-1.2); the craniocaudal liver span varied from 12 to 20 cm (mean=16 cm); hepatomegaly was present in 2 (22.2%) patients; the caudate-to-right lobe ratio was normal in all patients, with a mean of 0.36 (range: 0.22-0.47); the preportal space distance was enlarged in 2 cases (mean=7.5 mm, range: 1-16 mm); porta hepatis lymph nodes were present in 7 (77.8%) patients, and their mean dimensions were 11 mmx8 mm (large axis range: 6-19 mm, short axis range: 4-14 mm); and no patient had ascites. There was a significant difference in the craniocaudal liver span between patients with NASH (mean=21 cm) and patients with steatosis (mean=16 cm) (P<0.05). The caudate-to-right-lobe ratio was also significantly different between patients with NASH (mean=0.43) and patients with steatosis (mean=0.36) (P<0.05). There were no significant differences in liver-to-spleen attenuation ratios, measurements of preportal space, or the presence of porta hepatic lymph nodes. CONCLUSION: The CT features of NASH include steatosis, hepatomegaly, and porta hepatis lymph nodes, and the liver-to-spleen attenuation ratio correlated with the degree of steatosis on histopathology. Patients with NASH had a greater liver span and increased caudate-to-right-lobe-ratio compared with patients with steatosis alone.     

Diagnosis of liver cirrhosis with US: receiver-operating characteristic analysis of multidimensional caudate lobe indexes

To assess the utility of changes in the volume of the caudate lobe in the sonographic diagnosis of liver cirrhosis, the authors studied 58 patients with histologically proved cirrhosis, 18 patients with fatty liver, 28 patients with liver metastases, seven patients with lymphomatous liver involvement, and 75 healthy individuals. The longitudinal (CL), transverse (CT), and anteroposterior (CAP) diameters of the caudate lobe and the transverse diameter of the right lobe (RL) were measured, and one-, two-, and three-dimensional caudate lobe indexes and ratios were calculated. The analysis of the diagnostic performance of these criteria, compared by means of receiver-operating characteristic curves, revealed that the ratio of the three-dimensional caudate index (CI3) to the right lobe diameter (CI3/RL = [CL X CT X CAP]/RL) was superior to all other calculated criteria. At a specificity of 95%, the sensitivity of CI3/RL was 94.7%, compared with 73.3% for CT/RL. No significant differences were found between the control group and patients with fatty liver, metastases, or lymphomatous involvement. The study suggests that CI3/RL is the most reliable quantitative criterion for the US diagnosis of liver cirrhosis.     

Uneven steatosis and focal spared areas: modifications in the echographic pattern during chemotheraphy and clinical correlations

Hepatic steatosis induced by antiblastic chemotheraphy leads to differential diagnostic problems. It is difficult to recognize the true nature of hypoechoic areas in fatty liver in neoplastic patients treated by chemotheraphy, because skip areas due to nonsteatotic parenchyma and metastases may have very similar appearances. We studied with sonography 61 patients during chemotherapy and at different times during follow-up. The US findings were compared with laboratory data (liver function tests, serum cholesterol, and triglycerides). The final diagnosis was made by CT examination and/or liver biopsy. No correlations were found between US and laboratory data. However, a mean time could be determined for the occurrence of hepatic steatosis (diffuse steatosis: 72 days, SD ± 15 days; focal steatosis: 53 days, SD ± 12 days) as well as for its regression (53 days, SD ± 9 days for diffuse steatosis and 62 days, SD ± 15 days for focal steatosis) in close temporal relationship with previous chemotheraphy. These data might be of diagnostic value in the US assessment of neoplastic patients upon follow-up. In fact, focal hypoechoic areas occuring within the mean expected time in which steatosis takes place should more likely be benign (skip areas), and as such, disappear when liver steatosis regresses. On the contrary, the persistence of such images as well as their appearance beyond the expected mean time for hepatic steatosis to occur are highly suspicious for metastases and require further diagnostic work-up (CT, biopsy). Correspondence to: P. Gimondo     

Image fusion analysis of 99mTc-HYNIC-Tyr3-octreotide SPECT and diagnostic CT using an immobilisation device with external markers in patients with endocrine tumours

Purpose The aim of this study was to assess the value of multimodality imaging using a novel repositioning device with external markers for fusion of single-photon emission computed tomography (SPECT) and computed tomography (CT) images. The additional benefit derived from this methodological approach was analysed in comparison with SPECT and diagnostic CT alone in terms of detection rate, reliability and anatomical assignment of abnormal findings with SPECT.Methods Fifty-three patients (30 males, 23 females) with known or suspected endocrine tumours were studied. Clinical indications for somatostatin receptor (SSTR) scintigraphy (SPECT/CT image fusion) included staging of newly diagnosed tumours (n=14) and detection of unknown primary tumour in the presence of clinical and/or biochemical suspicion of neuroendocrine malignancy (n=20). Follow-up studies after therapy were performed in 19 patients. A mean activity of 400 MBq of ^99mTc-EDDA/HYNIC-Tyr³-octreotide was given intravenously. SPECT using a dual-detector scintillation camera and diagnostic multi-detector CT were sequentially performed. To ensure reproducible positioning, patients were fixed in an individualised vacuum mattress with modality-specific external markers for co-registration. SPECT and CT data were initially interpreted separately and the fused images were interpreted jointly in consensus by nuclear medicine and diagnostic radiology physicians.Results SPECT was true-positive (TP) in 18 patients, true-negative (TN) in 16, false-negative (FN) in ten and false-positive (FP) in nine; CT was TP in 18 patients, TN in 21, FP in ten and FN in four. With image fusion (SPECT and CT), the scan result was TP in 27 patients (50.9%), TN in 25 patients (47.2%) and FN in one patient, this FN result being caused by multiple small liver metastases; sensitivity was 95% and specificity, 100%. The difference between SPECT and SPECT/CT was statistically as significant as the difference between CT and SPECT/CT image fusion (P<0.001). Twenty-seven abnormal SPECT findings in 17 patients could not be initially assigned to organs, but were clearly delineated after image fusion. In 21 patients (40%), clinically relevant information was obtained by image fusion as compared with SPECT alone.Conclusion Co-registration of SPECT and diagnostic CT using a cost-effective immobilisation device provides excellent accuracy for tumour detection of endocrine malignancies and is superior to SPECT and CT alone. Image fusion reduces false positive results and can detect additional lesions. Anatomical information provided by CT enables precise localisation of abnormalities observed in SPECT.     

Liver metastases from colorectal carcinoma: detection with continuous CT angiography.

A diagnostic approach to assess liver metastases from colorectal carcinoma was prospectively evaluated in 30 patients with and without metastases on the basis of findings at conventional computed tomography (CT). With the technique, termed continuous CT angiography (CCTA), CT data were continuously sampled for 24 seconds at the same section level after initiation of a 3-second injection of 10-20 mL of contrast medium in the common hepatic artery. The procedure was repeated for each contiguous section level of the liver. Findings at preoperative ultrasound (US), conventional CT, and CCTA were compared with those at intraoperative US and surgical exploration as the standard of reference. Forty-four liver metastases were identified in 16 patients, and 14 patients had no metastases. CCTA had a sensitivity of 98% (43 lesions identified) and higher accuracy (81% [54 of 67 diagnoses]) than US and conventional CT. The data indicate that CCTA can supplement information obtained with conventional imaging techniques in patients who must undergo hepatic surgery because of metastases from colorectal carcinoma.     

Opportunistic Screening of Patients for Hepatic Steatosis: Clinical Follow-Up and Diagnostic Yield

PurposeHepatic steatosis is a common incidental finding on abdominal imaging that is not always reported or recognized as having clinical significance. Because of its association with liver disease, cirrhosis, and diabetes, the aim of this study was to bring attention to this finding and provide clinical guidance to referring clinicians by inserting standardized text into radiology reports of patients with incidentally detected hepatic steatosis.MethodsPatients with incidentally discovered hepatic steatosis on abdominal ultrasound or CT had standard text inserted into the impression sections of their diagnostic imaging reports. A total of 1,256 patients whose reports were tagged between April 2016 and September 2017 were retrospectively identified and their electronic medical records reviewed to determine subsequent acknowledgment in the medical record or clinical action in response to the tagged report. Information regarding patient demographics, the type of provider who ordered the examination, and the acuity of the examination results was also recorded.ResultsAcknowledgment and subsequent clinical action were more likely in patients whose examinations was ordered by primary care providers, whose examination results were not urgent, and who were in the ultrasound group. The overall diagnostic yield in patients who underwent clinical evaluation was nonalcoholic fatty liver disease in 70%, nonalcoholic steatohepatitis in 6%, and alcoholic hepatitis in 17%.ConclusionsOpportunistic screening for incidental hepatic steatosis on abdominal CT and ultrasound is feasible, with substantial yield for patients with clinically important entities including nonalcoholic fatty liver disease and nonalcoholic steatohepatitis.