T2-weighted MR imaging for hepatic hemangiomas: comparison of breath-hold and non-breath-hold turbo spin-echo pulse sequences with phased-array multicoil

Background: We compared T2-weighted and heavily T2-weighted breath-hold turbo spin-echo (TSE) sequences with T2-weighted non-breath-hold TSE sequence to evaluate hepatic hemangiomas on magnetic resonance (MR) with a phased-array multicoil. Methods: Twenty-two patients with 27 hemangiomas were studied at 1.0-T scanner by using T2-weighted and heavily T2-weighted breath-hold TSE sequences (18 s each) and non-breath-hold T2-weighted TSE sequences with use of a phased-array multicoil. Images were quantitatively analyzed for tumor-to-liver signal-difference-to-noise ratios (SD/Ns) and tumor-to-liver signal intensity ratios (T/Ls) and qualitatively analyzed for tumor conspicuity and motion-induced image artifacts. Results: Quantitatively, T2-weighted breath-hold TSE images showed the highest SD/Ns among the three sequences, although the differences from the heavily T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were not statistically significant (p= 0.61 and 0.06, respectively). Heavily T2-weighted breath-hold TSE images showed the highest T/Ls among the three sequences. The differences from the T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were statistically significant (p < 0.001). Qualitatively, breath-hold TSE images were superior to non-breath-hold TSE images in terms of tumor conspicuity (p < 0.01) and motion artifacts (p < 0.01). Conclusion: T2-weighted breath-hold TSE sequence is superior to T2-weighted non-breath-hold TSE sequence in the evaluation of hepatic hemangiomas on MR with a phased-array multicoil. Received: 7 April 1997/Accepted: 28 May 1997     

MR cholangiopancreatography: comparison between half-Fourier acquisition single-shot turbo spin-echo and two-dimensional turbo spin-echo pulse sequences

Background: To compare half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance cholangiopancreatography (MRCP) with two-dimensional turbo spin-echo (2D TSE) MRCP for imaging pancreatobiliary diseases. Methods: Twenty-seven patients with biliary or pancreatic disease underwent MRCP on a 1.0-T scanner with a body phased-array coil. A T2-weighted HASTE sequence (18 s) and a T2-weighted 2D TSE sequence (45 s) were used during a breath-hold by the patient. The source images and maximum intensity projection images of both sequences were reviewed independently by two radiologists. Results: Motion artifacts were more severely pronounced with 2D TSE sequences than with HASTE sequences (p < 0.001). All obstructions and their sites were accurately identified with both sequences. Filling defects (calculi) in bile ducts were identified in all 22 segments (100%) with HASTE-MRCP, whereas calculi in 19 of 22 segments (86%) were identified with 2D TSE-MRCP (p= 0.25). Three missed sites on 2D TSE-MRCP were intrahepatic bile ducts. Conclusions: HASTE-MRCP is superior to 2D TSE-MRCP in terms of detecting motion artifacts and visualization of the pancreatic ducts. HASTE-MRCP is comparable to 2D TSE-MRCP for visualization of the biliary ducts and their obstruction and is superior to 2D TSE-MRCP for identification of calculi in intrahepatic bile ducts. Received: 16 April 1997/Accepted: 28 May 1997     

MR pyelography in the assessment of hydroureteronephrosis: single-shot thick-slab RARE versus multislice HASTE sequences

Background: We used magnetic resonance (MR) pyelography to compare the value of thick-slab single-shot rapid acquisition with relaxation enhancement (RARE) sequence with that of multislice half-Fourier acquisition single-shot turbo-spin-echo (HASTE) sequence in evaluating the full spectrum of morphologic features in a group of patients with hydronephrosis. Methods: MR pyelographic images, with the use of thick-slab RARE and multislice HASTE sequences in 90 patients, were evaluated for image quality, presence of hydronephrosis, and level and cause of obstruction. Results: HASTE sequences provided images of better quality than did RARE sequences (p < 0.001). There was no statistically significant difference in demonstrating the presence of hydronephrosis (p = 0.5) and level of obstruction (p = 0.125). Sensitivity, specificity, and accuracy in diagnosing cause of obstruction were 61.7%, 62.5%, and 62%, respectively, for RARE sequences and 80%, 82.5%, and 81%, respectively, for HASTE sequences, with a statistically significant difference (all p < 0.05). Conclusion: Multislice HASTE sequence provides better diagnostic information than does thick-slab RARE sequence, particularly in evaluating the cause of obstruction.     

Detection of lymph-node metastases in patients with gastric carcinoma: comparison of three MR imaging pulse sequences

Background: To compare the diagnostic accuracy of magnetic resonance (MR) images obtained with three different pulse sequences for lymph-node metastases in patients with gastric cancer. Methods: T1-weighted spin-echo (SE), breath-hold T2-weighted fast SE, and triphasic gadolinium-enhanced dynamic gradient-recall-echo (GRE) MR images obtained in 16 patients with gastric carcinoma were retrospectively reviewed. Regional lymph nodes were assigned to four different groups, and image review was conducted on a lymph-node group-by-group basis; 64 lymph-node groups were reviewed by two radiologists. Relative sensitivity, specificity, and accuracy were determined based on the findings with definitive surgery and follow-up imaging. Diagnostic accuracy was determined by means of receiver-operating-characteristic (ROC) analysis. Results: Relative sensitivities for lymph-node metastases with T1-weighted SE, breath-hold T2-weighted fast SE, and dynamic GRE images were 61%, 94%, and 59%, respectively. Relative sensitivity with breath-hold T2-weighted fast SE images was significantly greater than that with T1-weighted SE (p < 0.05) and dynamic GRE (p < 0.05) images. Diagnostic accuracy determined by ROC analysis was marginally higher with breath-hold T2-weighted fast SE (area under ROC curve [Az]= 0.87) than with T1-weighted SE (Az = 0.78, p= 0.08) and dynamic GRE (Az = 0.79, p= 0.12) images. Conclusion: Breath-hold T2-weighted fast SE sequence is useful in the detection of regional lymph-node metastases in patients with gastric carcinoma. Received: 11 November 1998/Revision accepted: 7 April 1999     

Focal nodular hyperplasia of the liver: detection and characterization with plain and dynamic-enhanced MRI

Background: We compared nonenhanced and dynamic gadolinium (Gd)–enhanced magnetic resonance imaging (MRI) appearances of hepatic focal nodular hyperplasia (FNH) as depicted with breath-hold MR sequences and assessed the detectability of the individual MR sequences used. Methods: We retrospectively reviewed 48 consecutive patients with FNH. All patients underwent nonenhanced (T1 fast low-angle shot [FLASH] and T2 half-Fourier acquisition [HASTE]) and dynamic Gd-enhanced (T1 FLASH) MRI between December 1997 and March 2000. Individual MR sequences were analyzed separately for number of lesions, signal intensity features, dynamic enhancement pattern, and the presence and enhancement profile of a central scar. Ninety-five percent confidence intervals of absolute discrepancy were calculated to define differences in lesion detection. Results: Seventy-seven lesions were found in 48 patients. Nonenhanced FLASH imaging depicted 59 (76.6%) lesions in 45 patients. HASTE images showed 55 (71.4%) lesions in 44 patients. On T1- and T2-weighted images, lesions appeared predominantly hypointense (69.5%) and hyperintense (72.7%), respectively. Arterial and portal venous dominant phase Gd-enhanced MRI demonstrated all 77 lesions (100%), most of which showed hypervascular (94.8%), homogeneous (97.4%), and incomplete (except the central scar: 58.4%) enhancement in the arterial phase. Portal venous phase images showed lesion isointensity (50.6%) or moderate hyperintensity (46.8%) with complete enhancement (central scar: 94.8%). A central scar was detected on nonenhanced T1-weighted images (hypointense: 100%), T2-weighted images (hyperintense: 100%), arterial phase (hypointense: 59.7%) and portal venous phase (hyperintense: 71.4%) Gd-enhanced images in 78%, 69.1%, 77.9%, and 75.3% of tumors, respectively. Conclusion: Arterial and portal venous phase Gd-enhanced T1-weighted sequences are superior to nonenhanced images in the detection of FNH. Typical MRI appearances include hypointensity on T1-weighted and hyperintensity on nonenhanced T2-weighted images. Most commonly, FNH shows a homogeneous (without scar) and strong enhancement during the arterial phase, with lesion isointensity or slight hyperintensity during the portal venous phase. Received: 15 May 2001/Revision accepted: 22 August 2001     

磁共振心电门控HASTE和呼吸门控TSE的肺部应用

目的评价磁共振心电门控HASTE和呼吸门控TSE在肺部的应用。方法经CT检查的正常志愿者组10例,病变组47例,分别行磁共振屏气心电门控HASTE和呼吸门控TSE扫描,分析其图像的特征、质量。正常组计算正常肺实质的信噪比,病变组计算病变的信噪比,正常肺实质与病变的对比度。结果心电门控HASTE肺实质信号较均匀,无心脏和大血管搏动伪影;呼吸门控TSE肺纹理丰富、清晰。正常肺实质的信噪比分别为4.41±0.82;2.43±0.40(t=12.17,P<0.01)。病变的信噪比分别为:6.58±3.31,4.51±1.86(t=0.05,P<0.01)。病变与正常肺的对比度分别为0.81±0.06;0.86±0.05(t=4.79,P<0.01)。CT和磁共振检查共发现病变91个,最小病变为3mm×3mm×4mm。其敏感性分别为:CT93%,心电门控HASTE99%,呼吸门控TSE91%。结论对于5mm以下的肺结节的检出,磁共振心电门控HASTE存在较大的潜力。     

Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions

Background: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. Methods: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor–liver signal intensity (T/L) ratios. Results: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion–liver C/N (CSE TE, 90 ms: 18.6 ± 14.0; TSE TE, 90 ms: 16.5 ± 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. Conclusions: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE. Received: 13 December 1994/Accepted after revision: 31 March 1995     

常规三维容积内插屏气检查序列与自由呼吸StarVIBE序列T1WI肝脏图像质量对比

目的 对比分析常规三维容积内插屏气检查（VIBE）与StarVIBE序列的图像质量,探讨StarVIBE序列自由呼吸扫描在肝脏T1WI中的应用价值。方法 对48例超声提示肝脏病变患者行StarVIBE序列自由呼吸扫描及常规VIBE序列屏气扫描,根据患者能否配合屏气16 s分为无法屏气组（n=24）及配合屏气组（n=24）;采用"5分法"对肝脏边缘锐利度、肝脏血管清晰度、病变清晰度、伪影、脂肪抑制效果及图像总体质量进行主观评分,并计算平扫信号强度变异系数（CV）及增强后病灶肝脏信号比（LLR）;比较组内2序列间及2组间StarVIBE序列的图像质量差异。结果 无法屏气组StarVIBE序列图像的主观评分及定量评估参数值均高于常规VIBE序列（P均<0.05）;配合屏气组StarVIBE序列图像病灶清晰度（平扫）、伪影及脂肪抑制效果评分低于常规VIBE序列（P均<0.05）,而2序列间其余主观评分及定量评估差异均无统计学意义（P均>0.05）。2组间StarVIBE序列LLR差异有统计学意义（P<0.05）,各项主观评分及CV差异均无统计学意义（P均>0.05）。结论 在肝脏T1WI中,对于能配合屏气患者,StarVIBE序列图像质量略差于常规VIBE序列;而对于无法屏气患者,StarVIBE序列可获得更佳图像质量。     

MR imaging of advanced gastric cancer: comparison of various MR pulse sequences using water and gadopentetate dimeglumine as oral contrast agents

Background: To evaluate clinical usefulness of oral contrast agents (gadopentetate dimeglumine and water) and to assess proper magnetic resonance (MR) imaging in evaluating advanced gastric cancer (AGC) by comparing different MR imaging techniques. Methods: Fifteen patients with AGC were imaged with a 1.0-T MR imager and body-array coil. All patients underwent surgery or laparascopic biopsy. Fast low-angle shot (FLASH), half-Fourier single-shot turbo spin-echo (HASTE), and true fast imaging with steady-state precession time (FISP) images were obtained after ingestion of 900 mL tap water in each patient, followed by postcontrast FLASH images after additional ingestion of gadopentetate dimeglumine (Gd-DTPA). Qualitative analysis including T-staging of AGC and scoring of imaging quality and quantitative analysis were performed prospectively. Results: In image quality and diagnostic accuracy of T-staging, FLASH imaging showed results slightly superior to those of other imaging modalities, and there was no great difference between using water and Gd-DTPA as an oral contrast agent. As for cancer-to-gastric lumen contrast-to-noise ratio (CNR), HASTE and true FISP imaging were superior to FLASH imaging with Gd-DTPA (p < 0.0001). In cancer-to-pancreas CNR, FLASH imaging without Gd-DTPA showed the best result. Conclusions: The use of Gd-DTPA as a positive contrast agent may not be imperative, and T1-weighted FLASH imaging in combination with true FISP imaging with ingestion of tap water can be very useful in evaluating AGC with MR imaging. Received: 29 October 1998/Revision accepted: 27 January 1999     

MRI增强T1高分辨力各同性容积激发序列与TSE T1W序列检出椎体转移瘤的对比分析

目的 比较增强MRI快速T1高分辨力各向同性容积激发（THRIVE）序列和TSE序列T1W检出椎体转移瘤的价值。方法 对31例经穿刺活检病理证实的椎体转移瘤患者行MR增强检查,增强后先后行常规矢状位TSE T1W序列和矢状位THRIVE序列扫描。比较2个序列显示转移瘤病灶的数目、SNR、CNR和病灶边缘清晰度、运动伪影评分。结果 TSE T1W序列和THRIVE序列扫描时间分别为2 min 55 s和33 s。增强后THRIVE序列显示病灶的数量与TSE T1W序列差异无统计学意义（Z=-0.816,P=0.414）。增强后THRIVE序列的SNR（432.54±271.60）、CNR（233.27±197.65）均低于TSE T1W序列的SNR（674.32±375.79）、CNR（312.38±207.49）,差异均有统计学意义（t=-4.366、-2.660,P<0.001、0.012）。TSE T1W序列显示病灶边缘较THRIVE序列清晰（Z=-4.082,P<0.001）,但运动伪影较THRIVE序列明显（Z=2.291,P=0.022）。结论 增强扫描THRIVE序列扫描时间短,运动伪影少,椎体转移瘤的检出数目与TSE T1WI序列相当,在椎体转移瘤的检查中取代TSE T1W序列具有可行性。     

Evaluation of Crohn disease activity with magnetic resonance imaging

Background: The purpose of this study was to assess the accuracy of magnetic resonance imaging (MRI) in evaluating Crohn disease (CD) activity. The intestinal inflammatory activity is usually present in patients under pharmacologic treatment, despite their clinical remission. Methods: Twenty patients with CD, all under pharmacologic treatment, were prospectively studied by MRI at 1.5 T as a periodic control. Positivity of three acute-phase reactants was considered an index of biologic activity (BA). T2-weighted, T2-weighted fat-suppressed turbo spin-echo, and breath-hold T1-weighted turbo field-echo sequences, before and after gadolinium intravenous injection, were obtained. A negative superparamagnetic contrast agent was orally administered. The following MRI parameters were qualitatively evaluated by three radiologists at the level of the affected bowel and compared with clinical data: wall thickness (WT), wall T2-weighted signal (T2W), wall contrast enhancement (WE), amount of fibrofatty proliferation (FP), and T2-weighted signal of fibrofatty proliferation on fat-suppressed images (T2FP). The κ coefficient of agreement was calculated. The Spearman rank correlation was used for the analysis of clinical and radiologic data. Results: Nineteen of 20 patients were in clinical remission (Crohn Disease Activity Index < 150). On the basis of laboratory tests, nine of 20 patients had biologically active disease. An excellent correlation was found between BA and WE, T2W, and T2FP (0.900, 0.927 and 0.961, respectively; p < 0.0001), and a lower correlation was found between BA and WT and between BA and FP (0.78 and 0.62). Excellent statistical correlation was also found between WE and T2W and between WE and T2FP (0.876 and 0.892). Conclusions: An excellent statistical correlation was found between biologically “active” disease and the following MRI parameters: wall gadolinium enhancement, wall hyperintensity on T2-weighted fat-suppressed images, and hyperintensity of fibrofatty proliferation on T2-weighted fat-suppressed images. Therefore, MRI can be valuable in assessing CD activity. Received: 22 January 1999/Revision accepted: 3 November 1999     

Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery

Background: The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions. Methods: We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver–spleen contrast-to-noise ratio (CNR) and liver–lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader. Results: No significant difference was detected between R. trig. FSE and CSE or STIR in either liver–spleen CNR or liver–lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p < 0.01) and presence of artifact (p < 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p < 0.01) and CSE (p < 0.05). Conclusions: Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time. Received: 5 April 1995/Accepted: 2 May 1995     

自由呼吸StarVIBE序列用于采集胸部T1WI

目的 观察自由呼吸StarVIBE序列用于采集胸部T1WI的价值。方法 前瞻性收集37例CT提示胸部病变患者，根据能否配合屏气20 s分为无法屏气组（17例）及配合屏气组（20例），行StarVIBE序列及常规VIBE序列MR平扫及增强延迟期成像。以"5分法"评价两序列图像中病变清晰度、伪影、肺血管清晰度、纵隔结构清晰度及总体图像质量，并进行组间比较。结果 无法屏气组StarVIBE序列平扫及增强图像各项评分均高于常规VIBE序列（P均<0.05）。配合屏气组中，病变清晰度、肺血管清晰度评分在平扫StarVIBE序列图像中均低于常规VIBE序列（P均<0.05），但增强图像差异均无统计学意义（P均>0.05）；图像伪影及总体图像质量评分差异亦无统计学意义（P均>0.05），而纵隔清晰度评分在StarVIBE序列平扫及增强图像中均高于常规VIBE序列（P均<0.05）。结论 采集胸部T1WI时，对于能配合屏气者，自由呼吸StarVIBE序列可获得与常规VIBE序列相近的图像质量；而对于无法屏气者，自由呼吸StarVIBE序列可提供较好质量的图像。     

Detection of hepatocellular carcinoma and its metastases with various pulse sequences using superparamagnetic iron oxide (SHU-555-A)

Background: To identify the most useful combinations of various pre- and postcontrast magnetic resonance (MR) image sequences in detecting hepatocellular carcinoma (HCC) and its intrahepatic metastases before and after injection of SHU-555-A. Methods: Thirty-eight lesions in 16 patients were evaluated before and after administration of SHU-555-A by using fast spin echo (FSE), gradient echo (GRE), and echo planar (EP) imaging sequences using a 1.5-Tesla superconducting MR system. The signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) of the lesions, signal-to-noise ratios, and other parameters were calculated. Results: Tumors were better detected after injection of SHU-555-A on all pulse sequences except on out-of-phase T1-weighted (T1W)-GRE sequences. Tumor detectability was higher for precontrast EP imaging and T2*-weighted (T2*W)-GRE sequences, whereas detectability at postcontrast was higher for T2*W-GRE, proton-density-weighted-FSE, and in-phase T1W-GRE sequences. The SIR and CNR at precontrast were highest for EP imaging, and those at postcontrast were highest for T2*W-GRE. Conclusion: SHU-555-A will increase the detectability of HCC and its liver metastases. T1W- and T2*W-GRE sequences would be the sequences of choice. Received: 21 December 1998/Revision accepted: 5 May 1999     

Diffusion-weighted MR imaging with single-shot echo-planar imaging in the upper abdomen: preliminary clinical experience in 61 patients

Background: To determine the potential ability of diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar imaging (DW imaging) in the upper abdomen by apparent diffusion coefficient (ADC) and signal:intensity ratio (SIR) measurements. Methods: DW imaging was performed in 61 clinical patients. ADCs in the liver, pancreas, spleen, kidney, and different pathological conditions were calculated. Spleen-to-liver SIR and segmental intensity difference of the liver (SID) were also calculated. Results: The mean ADCs (mm²/s) were 2.28 × 10⁻³± 0.07 in the liver, 1.44 × 10⁻³± 0.05 in the spleen, 1.94 × 10⁻³± 0.19 in the pancreas, and 5.76 × 10⁻³± 0.06 in the kidney. The mean ADC of cirrhotic liver was 1.96 × 10⁻³± 0.62, which was lower than that of normal liver. Other pathologic conditions also showed ADCs different from those of normal tissues. All DW images showed significantly higher spleen-to-liver SIRs and SIDs than did T2-weighted images (p < 0.05). Conclusion: The mean ADCs obtained with DW imaging were different in each upper abdominal organ and with each pathologic condition. DW images showed better soft tissue contrast than did T2-weighted images with regard to SIR and CNR in depicting and characterizing upper abdominal disorders. Received: 24 July 1998/Revision accepted: 2 December 1998     

Benefits of tissue harmonic imaging in the evaluation of abdominal and pelvic lesions

Background: We compared tissue harmonic imaging (THI) and conventional ultrasonography to determine whether THI improves image quality and facilitates lesion characterization. Methods: Eighty-nine various abdominal or pelvic lesions in 71 patients(34 men and 37 women; age range = 3–90 years, median age = 52 years) were evaluated with conventional ultrasonography and THI. Examinations were performed with frequencies of 2–5 MHz. All the images were stored on a hard disk and evaluated separately by three radiologists. Results: According to the interpreters, THI improved overall image quality in 67 (74%) to 76 (84%) and lesion characterization in 28 (31%) to 36 (40%) of 89 lesions when compared with conventional ultrasonography. All three observers agreed that image quality and lesion characterization were improved in 62% and 17% of the lesions, respectively. Lesion groups containing five or more lesions were compared for any difference of improvement in overall image quality and lesion characterization. For overall image quality, a significant difference was found (p < 0.05). For lesion characterization, there was no significant difference between groups (p > 0.05). Conclusion: THI improved overall image quality and lesion characterization.     

MR imaging of cervical carcinoma: comparison among T2-weighted,dynamic, and postcontrast T1-weighted images with histopathological correlation

Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images. Received: 10 November 1995/Accepted after revision: 13 March 1996     

Small hepatocellular carcinoma: differentiation from adenomatous hyperplasia with color Doppler US and dynamic Gd-DTPA-enhanced MR imaging

Background: To investigate the usefulness of color Doppler ultrasound (US) and dynamic Gd-DTPA-enhanced magnetic resonance (MR) imaging in the differentiation of small hepatocellular carcinoma (HCC) and adenomatous hyperplasia (AH). Methods: Thirty-eight small (3 cm or less) nodular lesions (in 38 cirrhotic patients) with US features consistent with HCC underwent evaluation with color Doppler US and MR imaging. Breath-hold T1-weighted rapid acquisition spin echo MR sequence after bolus injection of 0.1 mmol/kg gadopentetate dimeglumine was used to evaluate dynamic enhancement. US-guided tissue-core percutaneous biopsy established the diagnosis: HCC in 28 cases and AH in 10. Results: Color signals with pulsatile or continuous Doppler spectrum were demonstrated in 19 of 28 HCCs (68%) but in none of the AHs. Although there was considerable overlap in signal intensity between HCC and AH on both unenhanced T1- and T2-weighted images, early enhancement on breath-hold T1-weighted images obtained 40 s after starting contrast administration was observed in 22 of 28 HCCs (79%) but in none of the AHs. In 26 of 28 HCCs (93%), pulsatile or continuous flow at color Doppler US, early enhancement at dynamic MR imaging, or both were observed. Conclusion: Findings with color Doppler US and dynamic Gd-DTPA-enhanced MR imaging enable a reliable distinction between small HCC and AH. Received: 8 August 1994/Accepted after revision: 27 January 1995     

Detection of pancreatic adenocarcinoma: relative value of arterial and late phases of spiral CT

Background: Spiral computed tomography (CT) allows the pancreas to be imaged during peak contrast levels owing to the capability of fast data acquisition. The objective of this study was to evaluate the relative value of the arterial and late phases of spiral CT for detecting pancreatic adenocarcinomas. Methods: Twenty-two patients with pathologically proved pancreatic adenocarcinomas underwent two-phase spiral CT. The CT scans were performed with 5 mm collimation and 5 mm/s table speed. Images during the arterial and late phases were obtained at 30- and 180-second delays, respectively. The images of the arterial phase were compared with those of the late phase in terms of tumor conspicuity from surrounding pancreatic parenchyma and tumor detectability by means of a 3-point grading system: 1 (poor), 2 (fair), and 3 (good). Results: In terms of tumor conspicuity from surrounding pancreatic parenchyma, 16 lesions (73%) were good, 5 lesions (23%) were fair, and 1 lesion (4%) was poor during the arterial phase, whereas 6 lesions (27%) were good, 9 lesions (41%) were fair, and 7 lesions (32%) were poor during the late phase (p= 0.0007). The arterial phase was superior to the late phase in 16 patients (73%) and equal in 6 patients (27%). For tumor detectability, 18 lesions (82%) were good, 3 lesions (14%) were fair, and 1 lesion (4%) was poor during the arterial phase, whereas 10 lesions (45%) were good, 7 lesions (32%) were fair, and 5 lesions (23%) were poor during the late phase (p= 0.0033). For detectability, the arterial phase was superior to the late phase in 14 patients (64%) and equal in 8 patients (36%). Conclusion: The arterial phase of spiral CT is superior to the late phase, which is equivalent to conventional CT for detecting pancreatic adenocarcinoma. Received: 1 August 1995/Accepted: 12 September 1995     

Value of endorectal coil versus body coil MRI for diagnosis of recurrent pelvic malignancies

Background: To compare endorectal coil magnetic resonance imaging (MRI) with body coil MRI in detecting local recurrence of gynecologic tumors and prostate and rectal cancers. Methods: Forty-six patients with suspected recurrent pelvic malignancies (13 gynecologic, 15 prostatic, and 18 anorectal primaries) were enrolled in the study. Axial T1- and T2-weighted body coil images and T2- and contrast-enhanced T1-weighted axial endorectal coil images were obtained on a 1.5 T system. Results of the MR examinations were compared with histogical findings and follow-up examinations with respect to the diagnostic accuracy and diagnostic confidence for assessment or exclusion of local recurrence. Results: Recurrent disease was histologically confirmed in eight patients with primary gynecologic malignancies, seven with suspected prostatic recurrence, and seven with suspected anorectal recurrence. Overall, accuracy of body coil MRI was 67% for gynecologic tumors, 36% for prostatic recurrences, and 59% for rectal recurrences. T2- and contrast-enhanced T1-weighted endorectal sequences yielded similar results, with an accuracy of 73% for depiction of gynecologic recurrence, 77% for prostatic recurrence, and 77% for rectal recurrence. The difference in accuracy between body coil and endorectal coil examinations was statistically significant (p < 0.05) only for prostatic cancer. Diagnostic confidence was, however, significantly improved (p < 0.05) in all tumors (T2-weighted endorectal coil examination was superior to T2-weighted body coil images in 71% of cases). Conclusion: Although the results of endorectal coil MRI are only slightly superior to those of body coil MRI for the detection of recurrent gynecologic and anorectal tumors, diagnosis can be made with greater diagnostic confidence in many cases. For detection of prostatic recurrence, endorectal MRI is highly recommended. Received: 27 April 1995/Accepted: 17 June 1995