Shinya Shiraishi

Diffusion-weighted magnetic resonance imaging for diagnosing malignant pulmonary nodules/masses: Comparison with positron emission tomography

Introduction: Recent developments of diffusion-weighted magnetic resonance imaging (DWI) make it possible to image malignant tumors to provide tissue contrast based on difference in the diffusion of water molecules among tissues, which can be measured by apparent diffusion coefficient (ADC) value. The aim of this study is to examine the usefulness of DWI for benign/malignant discrimination of pulmonary nodules/masses compared with 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET). Methods: PET and DWI were carried out prospectively in 104 patients with 140 pulmonary nodules/masses before surgery. FDG uptake of each lesion was quantitatively measured by a contrast ratio of standard uptake value (SUV-CR) between the lesions and contralateral lung. Diffusion of water molecule in each lesion was quantitatively measured by a minimum ADC (ADC-min). The diagnostic results were compared between the two modalities. Results: The receiver operating characteristics curve showed cutoff values of the ADC-min and the SUV-CR for benign/malignant discrimination to be 1.1 × 10−3 mm2/s and 0.37, respectively. DWI and PET showed sensitivities of 0.70 and 0.72 and specificities of 0.97 and 0.79, respectively. Although there was no significant difference in sensitivity between the two methods, DWI showed a significantly higher specificity than PET because of fewer false-positives for active inflammatory lesions (p = 0.03). The ADC-min and SUV-CR values showed a significant reverse correlation (r = −0.504, p < 0.001). Conclusions: DWI may be able to be used in place of FDG-PET to distinguish malignant from benign pulmonary nodules/masses with fewer false-positive results compared with FDG-PET.

Diffusion-weighted magnetic resonance imaging can be used in place of positron emission tomography for N staging of non–small cell lung cancer with fewer false-positive results

OBJECTIVE One of the deficiencies of positron emission tomography for N staging in lung cancer is a false-positive result caused by concurrent lymphadenitis. Recently, diffusion-weighted magnetic resonance imaging has been reported to be able to image tumors of body organs. The aim of this study is to examine the usefulness of diffusion-weighted magnetic resonance imaging for N staging of non-small cell lung cancer compared with positron emission tomography-computed tomography. METHODS Both positron emission tomography-computed tomography and diffusion-weighted magnetic resonance imaging were prospectively used in 88 patients before surgical intervention for non-small cell lung cancer to examine 734 lymph node stations. The diagnostic results of positron emission tomography-computed tomography and diffusion-weighted magnetic resonance imaging were compared. The diameters of the metastatic foci within lymph nodes were measured on hematoxylin and eosin-stained sections to compare the detectable size of metastatic foci between positron emission tomography-computed tomography and diffusion-weighted magnetic resonance imaging. RESULTS The accuracy of N staging in the 88 patients was 0.89 with diffusion-weighted magnetic resonance imaging, which was significantly higher than the value of 0.78 obtained with positron emission tomography-computed tomography (P = .012), because of less overstaging in the former. Among the 734 lymph node stations examined pathologically, 36 had metastases, and the other 698 did not. Although there was no significant difference in the diagnosis of the 36 metastatic lymph node stations between the 2 methods, diffusion-weighted magnetic resonance imaging was more accurate for diagnosing the 698 nonmetastatic stations than positron emission tomography-computed tomography because of fewer false-positive results (P = .002). The detectable size of metastatic foci within lymph nodes was 4 mm in both positron emission tomography-computed tomography and diffusion-weighted magnetic resonance imaging. CONCLUSIONS Diffusion-weighted magnetic resonance imaging can be used in place of positron emission tomography-computed tomography for N staging of non-small cell lung cancer with fewer false-positive results compared with positron emission tomography-computed tomography.

Is diffusion-weighted magnetic resonance imaging superior to positron emission tomography with fludeoxyglucose F 18 in imaging non–small cell lung cancer?

OBJECTIVE This retrospective analysis examined whether diffusion-weighted magnetic resonance imaging might be as useful as positron emission tomography with fludeoxyglucose F 18 for (1) discriminating between non-small cell lung cancer and benign pulmonary nodules and (2) predicting aggressiveness of non-small cell lung cancer. METHODS Diffusion-weighted magnetic resonance imaging and positron emission tomography were performed before surgery in 110 patients with 124 pulmonary nodules smaller than 3 cm, including 96 non-small cell lung cancers and 28 benign nodules. Diffusion of water molecules in magnetic resonance imaging was measured by minimum value of apparent diffusion coefficient. The criterion standard was the result of histologic diagnosis or follow-up examination. Sensitivity and specificity for differentiating between cancers and benign nodules were compared between diffusion-weighted imaging and positron emission tomography. Apparent diffusion coefficient in diffusion-weighted imaging and fludeoxyglucose F 18 uptake in positron emission tomography were examined with respect to pathologic tumor stage; lymphatic, vascular and pleural involvements; and histologic differentiation. RESULTS There were no significant differences between diffusion-weighted magnetic resonance imaging and positron emission tomography in sensitivity or specificity for non-small cell lung cancer. Whereas positron emission tomography showed significant differences in fludeoxyglucose F 18 uptake between pathologic stages IA versus IB or more advanced stages; between tumors with and without lymphatic, vascular, or pleural involvement; and between well-differentiated and moderately or poorly differentiated adenocarcinomas (P <.01-0.001), no significant differences in apparent diffusion coefficient values in were observed. CONCLUSION Diffusion-weighted magnetic resonance imaging is equivalent to positron emission tomography in distinguishing non-small cell lung cancer from benign pulmonary nodules but is not as useful for predicting aggressiveness of non-small cell lung cancer.

Initial experience with X-ray CT based attenuation correction in myocardial perfusion SPECT imaging using a combined SPECT/CT system

Objective: Attenuation artifacts adversely affect the diagnostic accuracy of myocardial perfusion imaging. We assessed the clinical usefulness of X-ray CT based attenuation correction (AC) in patients undergoing myocardial perfusion imaging by comparing their myocardial AC- and non-corrected (NC) SPECT images with the coronary angiography (CAG).Methods: We retrospectively reviewed the myocardial SPECT images of 30 patients (18 men, 12 women; mean age 68 years). Thirteen of 30 patients with coronary artery disease (CAD) and 17 without CAD were confirmed by CAG. They underwent sequential CT and myocardial SPECT imaging with thallium-201 (111 MBq) under an exercise or pharmacological stress protocol using our combined SPECT/ CT system. Two readers reviewed the myocardial SPECT images for the presence of CAD on a 4-point scale where 1 = normal, 2 = probably normal, 3 = probably abnormal, and 4 = abnormal. Two reading sessions were held. First, non-corrected (NC)-SPECT and second, AC-SPECT images using X-ray CT images were interpreted. Interobserver variability was assessed with kappa statistics. Diagnostic performance (accuracy) of coronary arterial stenosis was compared between AC- and NC-images.Results: Interobserver agreement for visual assessment was substantial or almost perfect. For AC-images, the observer consensus for analysis was 0.84 for the LAD-, 0.87 for the LCX-, and 0.71 for the RCA-territory. For NC-images, it was 0.91, 0.71, and 0.78. AC resulted in statistically significant improvements in overall diagnostic accuracy (sensitivity/ specificity/accuracy = 76%/93%/89%, 67%/86%/81%, respectively, for AC- and NC-images).Conclusions: Because of an increase in the specificity, diagnostic accuracy was significantly increased on AC-images. These preliminary data suggest that X-ray CT based AC in myocardial SPECT imaging has the potential to develop into a reliable clinical technique.

Management of sentinel lymph nodes in malignant skin tumors using dynamic lymphoscintigraphy and the single-photon-emission computed tomography/computed tomography combined system

BackgroundThe differentiation of true sentinel lymph nodes from nonsentinel lymph nodes is difficult in cases of multiple radiolabeled or dyed lymph nodes.MethodsWe examined the locations of sentinel lymph nodes in melanoma and other malignant skin tumors by using dynamic lymphoscintigraphy and the single-photon-emission computed tomography/computed tomography (SPECT/CT) combined system.ResultsSentinel lymph nodes were detected in 45 of the 53 patients examined using only the ordinary blue dye method (85%), and were detected in all 35 patients examined using the SPECT/CT method (100%). Twenty of the 35 patients mentioned above had one sentinel lymph node. Multiple sentinel lymph nodes were demonstrated in the head and neck areas using the SPECT/CT method. Significant differences (P = 0.0015) in the numbers of sentinel lymph nodes were found between the blue dye method only and the SPECT/CT method in the neck area. Popliteal sentinel lymph nodes were recognized in three patients, and cubital sentinel lymph nodes were recognized in two patients. Two patients had plural regional lymph nodes: one had popliteal and groin sentinel lymph nodes, while the other had cubital and axillary sentinel lymph nodes. The probe counts of the popliteus and cubitus were significantly lower (P = 0.0241) than the counts in the groin, axilla, and neck areas. Micrometastatic sentinel lymph nodes were recognized in four patients, and two patients had metastases in both sentinel and nonsentinel lymph nodes.ConclusionsDynamic lymphoscintigraphy was useful when we were concerned about cubital and popliteal lymph nodes. The SPECT/CT combined system was useful in recognizing the anatomical location of sentinel lymph nodes before biopsy. The detection rate of sentinel lymph nodes using the SPECT/CT method was always better than that with the blue dye method (P = 0.0197).

Prediction of left main or 3-vessel disease using myocardial perfusion reserve on dynamic thallium-201 single-photon emission computed tomography with a semiconductor gamma camera

BACKGROUND Myocardial perfusion imaging (MPI) may fail to detect balanced ischemia. We evaluated myocardial perfusion reserve (MPR) using Tl dynamic single-photon emission computed tomography (SPECT) and a novel cadmium zinc telluride (CZT) camera for predicting 3-vessel or left main coronary artery disease (CAD). METHODS AND RESULTS: A total of 55 consecutive patients with suspected CAD underwent SPECT-MPI and coronary angiography. The MPR index was calculated using the standard 2-compartment kinetic model. We analyzed the utility of MPR index, other SPECT findings, and various clinical variables. On multivariate analysis, MPR index and history of previous myocardial infarction (MI) predicted left main and 3-vessel disease. The area under the receiver operating characteristic curve was 0.81 for MPR index, 0.699 for history of previous MI, and 0.86 for MPR index plus history of previous MI. MPR index ≤1.5 yielded the highest diagnostic accuracy. Sensitivity, specificity, and accuracy were 86%, 78%, and 80%, respectively, for MPR index, 64%, 76%, 73% for previous MI, and 57%, 93%, and 84% for MPR index plus history of previous MI. CONCLUSIONS Quantification of MPR using dynamic SPECT and a novel CZT camera may identify balanced ischemia in patients with left main or 3-vessel disease.

Quantification of the impact of segmentectomy on pulmonary function by perfusion single-photon-emission computed tomography and multidetector computed tomography

OBJECTIVE The impact of segmentectomy for preservation of pulmonary function was quantified by using a co-registered perfusion single-photon-emission computed tomography and multidetector computed tomography (SPECT/CT). METHODS Pulmonary function tests and perfusion SPECT/CT were conducted before and after segmentectomy in 56 patients. Actual values of forced expiratory volume in 1 second (FEV(1)) after segmentectomy were compared with the FEV(1) after virtual lobectomy, which was calculated by SPECT/CT. The preoperative and postoperative FEV(1) of each lobe that had undergone segmentectomy was measured by SPECT/CT. RESULTS The mean percent of FEV(1) preserved after segmentectomy was significantly higher than the value after virtual lobectomy (88% +/- 9% vs 77% +/- 7%; P < .001). Whereas the mean value of the preoperative FEV(1) of each lobe that was undergoing segmentectomy was 0.51+/-0.21 L, segmentectomy could preserve 41% +/- 24% of it. The FEV(1) of each lobe after the resection of more than three segments (n = 4) was preserved in 17% +/- 12% of the preoperative values, which was significantly less than 49% +/- 23% and 35% +/- 22% after the resection of one (n = 29) and two (n = 23) segments (P = .02 and .08, respectively). The FEV(1) of the left upper lobe after the upper division segmentectomy (n = 8) was preserved in 21% +/- 11% of the preoperative values, which was significantly less than 35% +/- 12% after the lingular segmentectomy (n = 7) (P = .03). CONCLUSION Segmentectomy can preserve the pulmonary function more significantly than lobectomy, except for the resection of more than three segments or the left upper division segmentectomy.

Prediction of pulmonary function after lung lobectomy by subsegments counting, computed tomography, single photon emission computed tomography and computed tomography: a comparative study

OBJECTIVE The aim of the present study was to determine the optimal method of predicting postoperative pulmonary function (PPF) after lung lobectomy. METHODS The forced expiratory volume in 1s (FEV(1)) was measured in 37 patients before and after lobectomy, and the following three methods of predicting the PPF were evaluated: (1) the number of functioning subsegments to be resected were counted (subsegments counting [SC]); (2) the volume of the functioning lung was calculated using CT images (quantitative CT); and (3) perfusion scintigraphy was performed using co-registered single photon emission computed tomography and CT imaging (SPECT/CT). The FEV(1) values predicted using these three methods were then compared with the measured postoperative FEV(1), and the correlations and differences were analyzed. RESULTS While a paired t-test showed the SPECT/CT method to have the smallest difference between the measured and the predicted FEV(1) values (0.05 l, p=0.33), followed by the quantitative CT method (0.07 l, p=0.07), and finally the SC method (0.15 l, p<0.001), the difference between the two values was not significantly different between the quantitative CT and SPECT/CT method (p=0.22). CONCLUSIONS While the SC method is inferior to both the quantitative CT and the SPECT/CT methods for predicting the PPF after lobectomy, the latter two methods are almost equally accurate.

Fused 99m-Tc-GSA SPECT/CT imaging for the preoperative evaluation of postoperative liver function: can the liver uptake index predict postoperative hepatic functional reserve?

PurposeTo evaluate the role of hepatic asialoglycoprotein receptor analysis in the preoperative estimation of postoperative hepatic functional reserve.MethodsWe obtained technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin (99mTc-GSA) SPECT/CT fusion images in 256 patients with liver disease scheduled for hepatic resection. The liver uptake value corrected for body surface area [LUV(BSA)] and liver uptake ratio (LUR) of the remnant were preoperatively estimated based on the fused images. These values were compared with the postoperative hepatic functional reserve.ResultsSignificant correlations were observed between LUV(BSA), LUR, and most conventional indicators of hepatic functional reserve. Postoperatively, nonpreserved liver functional reserve was observed in 15 of the 256 patients (5.8%). Remnant LUV(BSA) showed better correlation than remnant LUR or the other indicators. No patients with remnant LUV(BSA) above 28.0 manifested poor nonpreserved functional reserve. Using a LUV(BSA) of 27.0, it was possible to predict postoperative poor hepatic functional reserve at a sensitivity of 91%, specificity of 81%, and accuracy of 81% postoperatively. According to multivariate analysis, a low remnant LUV(BSA) was the only significant independent predictor of poor hepatic functional reserve.ConclusionsOur 99mTc-GSA SPECT/CT fusion imaging method was clinically useful for evaluating regional hepatic function and for predicting postoperative hepatic functional reserve.

Required area of lymph node sampling during segmentectomy for clinical stage IA non-small cell lung cancer

OBJECTIVE To investigate the required area of lymph node sampling during segmentectomy, especially for segmental nodes at the nonresected segments, we examined the distribution of sentinel nodes in patients with non-small cell lung cancer who underwent segmentectomy. METHODS Ninety-four patients with clinical T1 N0 M0 non-small cell lung cancer were treated by using segmentectomy and dissection of lymph nodes with sentinel node identification using (99m)Tc-phytate. Anatomic locations of the segments were classified as either anterior or posterior, and correlations of anatomic location with the distribution of sentinel nodes at the segmental nodes were then examined. RESULTS Of the 94 patients, segmental nodes at both the resected and nonresected segments could be dissected in 42 patients. Segmental sentinel nodes were found at the resected segments in 27 (64%) of these 42 patients, a frequency that was significantly higher than that (12/42 [29%]) seen at the nonresected segments (P = .001). Seven (47%) of the 15 patients with tumors in the anteriorly located segments had segmental sentinel nodes at the nonresected segments, a frequency that was significantly higher than that (4/24 [17%]) seen in patients with tumors in the posteriorly located segments (P = .04). CONCLUSION The lymphatic flow from the anteriorly located segment can frequently go directly to the segmental lymph nodes of the posteriorly located segment, probably because the lobar bronchi locate at the posterior side in the thorax. Therefore segmental lymph nodes should be dissected at both the resected and nonresected segments during segmentectomy, especially for tumors in the anteriorly located segment.