Apparent diffusion coefficient for discriminating metastatic lymph nodes in patients with squamous cell carcinoma of the head and neck

PURPOSE

We aimed to evaluate the apparent diffusion coefficient (ADC) values of metastatic lymph nodes in patients with squamous cell carcinoma (SCC) of the head and neck.

METHODS

Patients with metastatic lymph nodes underwent 1.5 Tesla diffusion-weighted magnetic resonance imaging (MRI). The ADC values of the histologically proven metastases were evaluated retrospectively and mean ADC values were compared using one-way analysis of variance test. Receiver operating characteristic analysis was performed to identify ADC threshold values.

RESULTS

We included 33 patients (27 males, 6 females; mean age, 60.7 years) with 53 metastatic lymph nodes in the study. Mean ADC values for nodal metastases of nasopharyngeal carcinoma (NPC) (n=7), oropharyngeal (n=12), laryngeal (n=27), and hypopharyngeal (n=7) carcinoma were (0.810±0.158)×10⁻³ mm²/s, (0.985±0.099)×10⁻³ mm²/s, (1.037±0.150)×10⁻³ mm²/s, and (0.948±0.081)×10⁻³ mm²/s, respectively. The mean ADC values of nodal metastases of NPC were significantly lower than ADC values of laryngeal carcinoma (LSCC) (P = 0.002). An ADC value less than 0.890×10⁻³ mm²/s was found to facilitate differentiation of NPC from LSCC with a sensitivity of 71% and specificity of 85% (area under the curve, 0.852).

CONCLUSION

The mean ADC values showed significant differences between nodal metastases of NPC and LSCC. Considering SCCs as a single group may affect the accuracy of ADC-based differentiation. Location of the primary tumor should be taken into account and cutoff values should be determined separately for each anatomical location.Diffusion-weighted imaging (DWI) has the potential to characterize and differentiate various head and neck carcinomas (1–4). Differentiating nodal metastases of SCC from other less common tumors of the head and neck is important for treatment planning. Previous studies have shown that apparent diffusion coefficient (ADC) values may be used to differentiate metastatic lymph nodes due to SCC from lymphoma (5). However, the results of some studies indicated that ADC values of SCCs and their nodal metastases (e.g., poorly differentiated SCC and nasopharyngeal carcinoma) may sometimes overlap with the ADC values of lymphoma (5–7). Thus, the efficacy of using DWI for differentiation depends largely on the histologic characteristics of the lymph node.Approaching all pharyngeal space SCCs as a single homogeneous group may affect the accuracy of ADC-based discrimination of metastatic lymph nodes due to SCC from other tumors. Therefore, we aimed to retrospectively evaluate and compare the ADC values of metastatic lymph nodes from carcinoma of the nasopharynx, oropharynx, larynx, and hypopharynx.     

MRI features of breast lymphoma: preliminary experience in seven cases

PURPOSE

We aimed to evaluate the imaging features of breast lymphoma using magnetic resonance imaging (MRI).

METHODS

This retrospective study consisted of seven patients with pathologically confirmed breast lymphoma. The breast lymphomas were primary in six patients and secondary in one patient. All patients underwent preoperative dynamic contrast-enhanced MRI and one underwent additional diffusion-weighted imaging (DWI) with a b value of 600 s/mm². Morphologic characteristics, enhancement features, and apparent diffusion coefficient (ADC) values were reviewed.

RESULTS

On MRI, three patients presented with a single mass, one with two masses, two with multiple masses, and one with a single mass and a contralateral focal enhancement. The MRI features of the eight biopsied masses in seven patients were analyzed. On MRI, the margins were irregular in six masses (75%) and spiculated in two (25%). Seven masses (87.5%) displayed homogeneous internal enhancement, while one (12.5%) showed rim enhancement. Seven masses (87.5%) showed a washout pattern and one (12.5%) showed a plateau pattern. The penetrating vessel sign was found in two masses (25%). One patient with two masses underwent DWI. Both masses showed hyperintense signal on DWI with ADC values of 0.867×10⁻³ mm²/s and 0.732×10⁻³ mm²/s, respectively.

CONCLUSION

Breast lymphoma commonly presents as a homogeneously enhancing mass with irregular margins and displays a washout curve pattern on dynamic MRI. A low ADC value may also indicate a possible diagnosis of breast lymphoma.Breast lymphoma, which constitutes only 0.04%–0.5% of all breast malignancies (1), can be divided into primary or secondary breast lymphoma (2). The majority of breast lymphomas are diffuse large B-cell lymphoma (3). The spontaneous regression of a breast lymphoma is rare and the five-year overall survival rate is 53% (1, 4). Early-stage identification and the use of radiotherapy are favorable prognostic factors, while mastectomy is associated with a poorer survival (1, 5). Therefore, a preoperative diagnosis of breast lymphoma would mean an earlier diagnosis and likely avoid unnecessary aggressive procedures.Previous studies demonstrated mammographic and ultrasonographic findings of breast lymphoma (6–8). Most lesions were high-density masses without spiculated margins and calcifications on mammography and noncircumscribed hypoechoic masses on ultrasonography (6–8). However, none were pathognomonic.Data on the magnetic resonance imaging (MRI) of breast lymphoma are limited to some single case reports (4, 7, 9–19) and small sample size case series (8, 20–23). The morphology and time-signal intensity curve (TIC) of breast lymphoma on MRI are variable. Diffusion-weighted imaging (DWI) is a functional imaging technique that is useful for distinguishing lymphoma from other malignant tumors in other systems (24, 25). However, to the best of our knowledge, the value of DWI in differentiating breast lymphoma from other malignant breast lesions has not been discussed. Therefore, the purpose of this study is to assess the MRI and DWI features of breast lymphoma.     

Region of interest demarcation for quantification of the apparent diffusion coefficient in breast lesions and its interobserver variability

PURPOSE

We aimed to compare two different methods of region of interest (ROI) demarcation and determine interobserver variability on apparent diffusion coefficient (ADC) in breast lesions.

METHODS

Thirty-two patients with 39 lesions were evaluated with a 3.0 Tesla scanner using a diffusion-weighted sequence with several b-values. Two observers independently performed the ADC measurements using: 1) a small fixed area of 10 mm² ROI within the area with highest restriction; 2) a large ROI so as to include the whole lesion. Differences were assessed using the Wilcoxon-rank test. Bland-Altman method and Spearman coefficient were applied for interobserver variability and correlation analysis.

RESULTS

ADC values measured using the two ROI demarcation methods were significantly different for both observers (P = 0.026; P = 0.033). There was no interobserver variability in ADC values using either method (large ROI, P = 0.21; small ROI, P = 0.64). ADC values of malignant lesions were significantly different between the two methods (P < 0.001). Variability in ADC was ≤0.008×10⁻³ mm²/s for both methods. When using the same method, ADC values were significantly correlated between the observers (small ROI: r=0.990, P < 0.001; large ROI: r=0.985, P < 0.001).

CONCLUSION

The choice of ROI demarcation method influences ADC measurements. Small ROIs show less overlap in ADC values and higher ADC reproducibility, suggesting that this method may improve lesion discrimination. Interobserver variability was low for both methods.Diffusion-weighted imaging (DWI) of the breast has been used to improve lesion diagnosis. However, due to lesion heterogeneity, differences between acquisition protocols, and lesion demarcation strategies, there is some overlap in apparent diffusion coefficient (ADC) values of different lesion types (1).Regarding lesion demarcation, different strategies can be found in the literature. Pereira et al. (2) suggest delimiting the whole lesion area, whereas others consider only its most solid part representing viable tumor (3, 4).A study focusing on the use of ADC minimum, average, and maximum to characterize breast lesions (5) has indirectly investigated the influence of region of interest (ROI) on ADC quantification, but has not specifically compared these two methods of demarcation. Here, we compare these two ROI demarcation methods and determine their interobserver variability in ADC quantification.     

Correlation of minimum apparent diffusion coefficient with maximum standardized uptake on fluorodeoxyglucose PET-CT in patients with rectal adenocarcinoma

PURPOSE

The aim of this study was to retrospectively assess the correlation between minimum apparent diffusion coefficient (ADC_min) values obtained from diffusion-weighted magnetic resonance imaging (MRI) and maximum standardized uptake values (SUV_max) obtained from positron emission tomography-computed tomography (PET-CT) in rectal cancer.

MATERIALS AND METHODS

Forty-one patients with pathologically confirmed rectal adenocarcinoma were included in this study. For preoperative staging, PET-CT and pelvic MRI with diffusion-weighted imaging were performed within one week (mean time interval, 3±1 day). For ADC measurements, the region of interest (ROI) was manually drawn along the border of each hyperintense tumor on b=1000 s/mm² images. After repeating this procedure on each consecutive tumor-containing slice to cover the entire tumoral area, ROIs were copied to ADC maps. ADC_min was determined as the lowest ADC value among all ROIs in each tumor. For SUV_max measurements, whole-body images were assessed visually on transaxial, sagittal, and coronal images. ROIs were determined from the lesions observed on each slice, and SUV_max values were calculated automatically. The mean values of ADC_min and SUV_max were compared using Spearman’s test.

RESULTS

The mean ADC_min was 0.62±0.19×10⁻³ mm²/s (range, 0.368–1.227×10⁻³ mm²/s), the mean SUV_max was 20.07±9.3 (range, 4.3–49.5). A significant negative correlation was found between ADC_min and SUV_max (r=−0.347; P = 0.026).

CONCLUSION

There was a significant negative correlation between the ADC_min and SUV_max values in rectal adenocarcinomas.Diffusion-weighted imaging (DWI) is a widely used technique for disease evaluation in oncology (1, 2). In rectal cancer, the applications of DWI include tumor detection, tumor characterization, distinguishing tumor tissue from nontumor tissue, and monitoring and predicting treatment response (3–8). For local staging of rectal cancer, adding DWI to conventional magnetic resonance imaging (MRI) yields better identification of tumor borders and locoregional lymph nodes than conventional MRI alone (9, 10).The apparent diffusion coefficient (ADC) map obtained from DWI shows the freedom of water diffusion, and values calculated on the map are useful parameters in tissue characterization. By performing diffusion-weighted (DW) MRI with at least two diffusion weightings, or b values, the differential signal attenuation at different b values can be used to calculate the ADC (2). Regardless of the tumor type and location, the ADC values reflect tumor morphology, including the cellular density, integrity of cell membrane, and nuclear-to-cytoplasm ratio (11, 12).Positron emission tomography/computed tomography (PET-CT) has become a crucial method in cancer imaging, both for diagnosis and staging, as well as for offering prognostic information based on tumor response. In PET-CT, the standardized uptake value (SUV) is a measure of fluorodeoxyglucose (FDG) uptake, which has been shown to be helpful in establishing the metabolic activity level of a tumor (13–15).Both ADC and SUV have been used as important imaging parameters to supplement visual interpretation. To our knowledge, few studies have evaluated the relationship between ADC and SUV in cancer patients (16–18). The aim of the present study was to retrospectively assess the correlation between the minimum ADC (ADC_min) on DWI and maximum SUV (SUV_max) values from FDG PET-CT in rectal cancer.     

Variations in apparent diffusion coefficient values following chemotherapy in pediatric neuroblastoma

PURPOSE

In children the assessment of solid tumors’ response to chemotherapy is based primarily on size reduction, which can be unreliable and a late marker, in the presence of necrosis. We aimed to establish whether apparent diffusion coefficient (ADC) values of childhood neuroblastomas show proportional changes in relation to chemotherapy response.

METHODS

We evaluated 15 pediatric patients with abdominopelvic neuroblastomas, who had undergone MRI before and after chemotherapy. Two radiologists retrospectively analyzed all images by drawing a round uniform region-of-interest in the solid/contrast-enhancing portion of the lesions in consensus. The ADC values from pre- and postchemotherapy images were compared.

RESULTS

Postchemotherapy ADC values were significantly higher than those obtained before treatment (P < 0.05, for minimum, maximum, and median ADC values).

CONCLUSION

Our results support diffusion-weighted MRI as a promising noninvasive biomarker of therapeutic responses. To the best of our knowledge, this is the first report to compare diffusion-weighted imaging findings before and after chemotherapy in childhood neuroblastic tumors.Diffusion-weighted (DW) magnetic resonance imaging (MRI) enables tracking of water molecules (Brownian motion) at a microscopic level. The use of different b values allows for the quantification of signal loss in diffusion-sensitive sequences through apparent diffusion coefficient (ADC) maps. It has been shown that highly cellular areas with restricted diffusion demonstrate low ADC values compared to areas with less cellular content. Recent technological advances, including echo-planar imaging, multichannel coils, and parallel imaging, allow for the usage of DW-MRI beyond neurological applications (1–5). The ADC values of malignant masses are relatively lower than those of benign masses, although overlapping ADC values of malignant and benign lesions have also been reported (1, 6–12). Currently, in children the assessment of solid tumors’ response to chemotherapy is based on size reduction; but this method can be unreliable as a marker, as tumors that shrink substantially may still be composed mainly of malignant cells (13, 14).Here, we aimed to evaluate whether ADC values in viable portions of childhood neuroblastomas show any changes depending on tumor cellularity before and after chemotherapy. We hypothesized that an increase in ADC values over the course of chemotherapy could be used as a noninvasive marker of therapy response. To the best of our knowledge, this is the first report to compare DW-MRI findings before and after chemotherapy in childhood neuroblastic tumors.     

Diffusion-weighted imaging in the assessment of tumour grade in endometrial cancer

Objective

Endometrial cancer is the most common gynaecological malignancy in developed countries. Histological grade and subtype are important prognostic factors obtained by pipelle biopsy. However, pipelle biopsy “samples” tissue and a high-grade component that requires more aggressive treatment may be missed. The purpose of the study was to assess the use of diffusion-weighted MRI (DW-MRI) in the assessment of tumour grade in endometrial lesions.

Method

42 endometrial lesions including 23 endometrial cancers and 19 benign lesions were evaluated with DW-MRI (1.5T with multiple b-values between 0 and 750 s mm⁻²). Visual evaluation and the calculation of mean and minimum apparent diffusion coefficient (ADC) value were performed and correlated with histology.

Results

The mean and minimum ADC values for each histological grade were 1.02 ± 0.29×10⁻³ mm² s⁻¹ and 0.74 ± 0.24×10⁻³ mm² s⁻¹ (grade 1), 0.88 ± 0.39×10⁻³ mm² s⁻¹ and 0.64 ± 0.36×10⁻³ mm² s⁻¹ (grade 2), and 0.94 ± 0.32×10⁻³ mm² s⁻¹ and 0.72 ± 0.36×10⁻³ mm² s⁻¹ (grade 3), respectively. There was no statistically significant difference between tumour grades. However, the mean ADC value for endometrial carcinoma was 0.97 ± 0.31, which was significantly lower (p<0.0001) than that of benign endometrial pathology (1.50 ± 0.14). Applying a cut-off mean ADC value of less than 1.28 × 10⁻³ mm² s⁻¹we obtained a sensitivity, specificity, positive predictive value and negative predictive value for malignancy of 87%, 100%, 100% and 85.7%, respectively.

Conclusion

Tumour mean and minimum ADC values are not useful in differentiating histological tumour grade in endometrial carcinoma. However, mean ADC measurement can provide useful information in differentiating benign from malignant endometrial lesions. This information could be clinically relevant in those patients where pre-operative endometrial sampling is not possible.Endometrial carcinoma is the commonest gynaecological malignancy in developed countries [1,2]. The majority of patients present with intermenstrual or post-menopausal bleeding, with approximately 70–80% having early (Stage I) disease at presentation [1,3]. Despite the relatively high incidence, endometrial cancer is not a common cause of cancer death with a 5 year survival of approximately 80% when all stages are considered together [4].The most important prognostic indicators in endometrial cancer are FIGO (International Federation of Gynecology and Obstetrics) stage, lymphovascular invasion, histological subtype and grade, and the presence of lymph node metastases [4-8]. FIGO staging of endometrial cancer is a surgico-pathological staging system that includes total hysterectomy, bilateral salpingo-oophrectomy and peritoneal washings with full pelvic lymphadenectomy [9]. The overall rate of lymph node involvement in endometrial cancer is low (5–8%) and lymphadenectomy carries a reported complication risk of up to 17–19% [10,11], which is particularly marked in patients who are at high surgical risk, such as those who are obese, diabetic or suffer from ischaemic heart disease [12]. As a result, only around 30% of endometrial cancer patients undergo lymphadenectomy in the USA as a whole, increasing to 48.3% in specialised cancer centres [13]. The role of lymphadenectomy in the management of endometrial cancer is currently an area of controversy in gynaecological oncology with no clear evidence regarding the survival benefits associated with the procedure [14-17]. However, in patients who are at high risk of nodal metastases most centres continue to perform lymphadenectomy.Accurate pre-operative identification of patients at high risk of nodal metastases would allow the selection of patients for lymphadenectomy, while those at low risk could be treated with simple hysterectomy. Histological tumour grade is a strong predictor of nodal invasion and thereby prognosis in endometrial cancer [18,19]. In patients with FIGO Stage 1 disease, grade 1 or grade 2 histology carries a less than 10% risk of nodal metastases. However, grade 3 histology carries an overall risk of 18% in Stage 1 disease, which increases to 34% when considering patients with deep myometrial invasion [18,19]. Pre-operative cytology from pipelle or curettage specimens only samples the endometrial tissue and therefore does not always provide accurate assessment [20,21]. In a study of patients with grade 1 histology pre-operatively 19% were upgraded following surgical resection [22].Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that looks at the Brownian motion of water in tissues. In biological tissues this is restricted by interactions with cell membranes and macromolecules on a microscopic level. Increased tissue cellularity, as seen in tumours, restricts Brownian motion, which can be quantified by calculation of the apparent diffusion coefficient (ADC) [23].Previous publications have demonstrated that endometrial carcinoma may be distinguished from normal endometrium on DW-MRI [24-30]. It has also been suggested that DW-MRI may be useful in the pre-operative assessment of tumour grade [26,31]. The purpose of this study is to determine if there is a correlation between histological tumour grade and ADC value in endometrial cancer.     

Comparison of diffusion-weighted MRI acquisition techniques for normal pancreas at 3.0 Tesla

PURPOSE

We aimed to optimize diffusion-weighted imaging (DWI) acquisitions for normal pancreas at 3.0 Tesla.

MATERIALS AND METHODS

Thirty healthy volunteers were examined using four DWI acquisition techniques with b values of 0 and 600 s/mm² at 3.0 Tesla, including breath-hold DWI, respiratory-triggered DWI, respiratory-triggered DWI with inversion recovery (IR), and free-breathing DWI with IR. Artifacts, signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) of normal pancreas were statistically evaluated among different DWI acquisitions.

RESULTS

Statistical differences were noticed in artifacts, SNR, and ADC values of normal pancreas among different DWI acquisitions by ANOVA (P < 0.001). Normal pancreas imaging had the lowest artifact in respiratory-triggered DWI with IR, the highest SNR in respiratory-triggered DWI, and the highest ADC value in free-breathing DWI with IR. The head, body, and tail of normal pancreas had statistically different ADC values on each DWI acquisition by ANOVA (P < 0.05).

CONCLUSION

The highest image quality for normal pancreas was obtained using respiratory-triggered DWI with IR. Normal pancreas displayed inhomogeneous ADC values along the head, body, and tail structures.Diffusion-weighted magnetic resonance imaging (DW-MRI) has increasingly expanded to abdominal organs thanks to newer technical developments. Diffusion-weighted imaging (DWI) can provide great details of functional and anatomic information that can be used in the differential diagnosis of abdominal pathological conditions. Investigators have recently reported that DWI can be utilized to detect pancreatic cancer (1, 2) and analysis of apparent diffusion coefficient (ADC) can help differentiate pancreatic masses (3–6). The single-shot spin-echo echo-planar imaging combined with parallel imaging technique is commonly employed for pancreatic DWI studies. Breath-hold DWI is the most common technique used for signal acquisition, especially on 1.5 Tesla (T) magnetic resonance (MR) system, because of its time efficiency. However, there are several disadvantages of breath-hold DWI, including poor signal-to-noise ratio (SNR), limited scan volume and significant artifacts (7, 8). Respiratory-triggered and free-breathing techniques are also used for signal acquisition in pancreatic DWI studies. Compared to breath-hold, the advantages of respiratory-triggered and free-breathing techniques are higher SNR due to multiple signal acquisitions, larger scanning range and less artifacts; their main disadvantage being the longer scanning time (9). Additionally, techniques of fat suppression, such as chemical shift selective (CHESS) and short tau inversion recovery, are essential for DWI in the pancreas for improving the contrast ratio and contrast-to-noise ratio of lesions with respect to normal pancreatic tissues (1, 6, 10).Previously, most investigations were performed using 1.5 T MR scanners. Pancreas imaging using DWI with 3.0 T MR system needs to be further clarified and understood due to its increasing application, which may be a challenging task because of specific absorption rate and various artifacts from high sensitivity to magnetic field inhomogeneity and physiological movement (11). The aim of this study was to investigate different DWI techniques to visualize normal pancreas using a 3.0 T MR scanner and determine the best image acquisition technique in terms of artifacts, SNR, and ADC.     

Changes in apparent diffusion coefficients in the normal uterus during different phases of the menstrual cycle

This study investigated the apparent diffusion coefficients (ADCs) of the uterine zonal structures (myometrium, endometrium and junctional zone) among reproductive women, and their changes during the menstrual cycle. Magnetic resonance (MR) images of seven healthy females (aged 24–31 years) were obtained during the periovulatory, luteal and menstrual phases. Diffusion-weighted imaging (DWI) was performed with a single-shot echo-planar imaging (EPI) sequence in the midsagittal plane of the uterus using three b-values (b = 0, 500 or 1000 s mm⁻²). The ADC values of the three uterine zonal structures were measured on an ADC map by placing two regions of interest (ROI) on the corresponding zonal structures. The average changes of ADC values (intra-individual ADC value variation) over three menstrual phases were 0.41 × 10⁻³ mm² s⁻¹ (range, 0.08–0.91) for myometrium, 0.55 × 10⁻³ mm² s⁻¹ (0.35–0.84) for endometrium, and 0.40 × 10⁻³ mm² s⁻¹ (0.18–0.59) for the junctional zone. The ADC values for myometrium and endometrium were lower in the menstrual phase, although there was some overlap of individual values. Interindividual variation in ADC value for a given zone or phase ranged from 0.48 × 10⁻³ mm² s⁻¹ to 0.85 × 10⁻³ mm² s⁻¹. Intermeasurement variation between the two ROIs ranged from 0 to 0.48 × 10⁻³ mm² s⁻¹ per measurement. The magnitude of these variations was comparable to reported differences between malignant and non-malignant tissues. These preliminary results, from a small number of subjects, suggest that the menstrual cycle and individual variation in pre-menopausal women should be considered when interpreting the ADC values of uterine structures.Diffusion-weighted imaging (DW) is an emerging functional imaging technique that is based on the diffusion of water molecules [1]. DWI can measure the apparent diffusion coefficient (ADC) of the water in tissue, which reflects its cell density, cellular oedema and microcirculation [1, 2]. Malignant tissue tends to have low ADC values, and so ADCs are increasingly used as a quantitative parameter to distinguish malignant tissue from non-malignant tissue [3–5]. Recent studies in gynaecological imaging have reported ADC values that were lower than normal in uterine cervical cancer, endometrial cancer and leiomyosarcoma [6–8].In pre-menopausal women, T₂ weighted images of the uterus, a three-layer zonal structure, change during the menstrual cycle [9–11]. When the variation in the appearance of the uterus on T₂ weighted images and the underlying physiological changes are considered, it seems possible that there might be variation of ADCs in the normal uterus during the menstrual cycle, which could affect the baseline ADC values used in the assessment of uterine abnormalities. Thus, the purpose of this study was to investigate the ADC values of each zonal structure in the uterus among reproductive women, and their variation in three different phases of the menstrual cycle.     

Development of a diffusion-weighted MRI protocol for multicentre abdominal imaging and evaluation of the effects of fasting on measurement of apparent diffusion coefficients (ADCs) in healthy liver

Objective:

To assess the effect of fasting and eating on estimates of apparent diffusion coefficient (ADC) in the livers of healthy volunteers using a diffusion-weighted MRI protocol with b-values of 100, 500 and 900 s mm⁻² in a multicentre study at 1.5 T.

Methods:

20 volunteers were scanned using 4 clinical 1.5-T MR scanners. Volunteers were scanned after fasting for at least 4 h and after eating a meal; the scans were repeated on a subsequent day. Median ADC estimates were calculated from all pixels in three slices near the centre of the liver. Analysis of variance (ANOVA) was used to assess the difference between ADC estimates in fasted and non-fasted states and between ADC estimates on different days.

Results:

ANOVA showed no difference between ADC estimates in fasted and non-fasted states (p = 0.8) nor between ADC estimates on different days (p = 0.8). The repeatability of the measurements was good, with coefficients of variation of 5.1% and 4.6% in fasted and non-fasted states, respectively.

Conclusion:

There was no significant difference in ADC estimates between fasted and non-fasted measurements, indicating that the perfusion sensitivity of ADC estimates obtained from b-values of 100, 500 and 900 s mm⁻² is sufficiently low that changes in blood flow in the liver after eating are undetectable beyond the variability in the measurements.

Advances in knowledge:

Assessment of the effect of prandial state on ADC estimates is critical, in order to determine the appropriate patient preparation for biological validation in clinical trials.Diffusion-weighted MRI (DW-MRI) has wide application in oncology with several studies indicating its utility for characterizing liver lesions.^1–6 DW-MRI is a relatively simple technique, which does not require administration of exogenous contrast agents, and provides qualitative and quantitative information. It measures the thermal mobility of water molecules in biological tissues, which is affected by their interactions with cell membranes and by the presence of macromolecules. The biexponential behaviour of the DW-MRI signal, which is characterized by a steep attenuation at low b-values (0–100 s mm⁻²) and a slower attenuation at higher b-values (>100 s mm⁻²), is believed to represent the perfusion of the blood in the microcirculatory vessels (so-called pseudodiffusion), and the diffusion of the extracellular water molecules, respectively.⁷ Until recently, most clinical studies have used a monoexponential curve fitted to b-values, 0–1000 s mm⁻² to estimate the apparent diffusion coefficient (ADC), where the reliability of this ADC estimation is affected by the lower b-values, thus including the influence from the pseudodiffusion component of the signal.^1,3,5 However, there is increasing recognition of the need to exclude the lower b-values in order to eliminate the effects of perfusion, particularly in tissues such as the liver where blood flow is high.^8–10Over the past decade, several investigators have proposed and documented the importance of the addition of DW-MRI sequences to the standard MR sequences for the identification of liver lesions as well as for assessing treatment response.^1,4,5 However, in clinical trials, variability of the measurement owing to technical (multivendor platforms) and biological (physiological variations) factors remains a challenge.¹¹ It is crucial, therefore, to standardize imaging protocols for data acquisition to minimize variability and achieve as reproducible a measurement as possible. To implement diffusion-weighted (DW) imaging in a clinical trial, standardized acquisition parameters within the capability of a range of scanner types should be addressed. Furthermore, in order to ensure reduction of physiological variation, the effects of patient preparation and biological status on the measurement need to be understood. Several individual studies in the literature have attempted to investigate the effect of calorie intake on the ADC estimates of the liver.^12–14 However, no study addresses the effect of fasting or feeding on the ADC measurement in the context of a standardized multivendor acquisition protocol in a multicentre study.We therefore designed a protocol with acquisition parameters that were implemented across 1.5-T scanners from a variety of manufacturers and prospectively studied the effects of fasting on the ADC estimates in healthy livers, recording the variability in the measurement at two time points. A minimum b-value of 100 s mm⁻² was employed in estimation of ADCs in order to minimize the influence of perfusion on our measurements.     

The role of the ADC value in the characterisation of renal carcinoma by diffusion-weighted MRI

The purpose of this study is to evaluate the role of diffusion-weighted imaging (DWI) in combination with T₁ and T₂ weighted MRI for the characterisation of renal carcinoma. The institutional review board approved the study protocols and waived informed consent from all of the patients. 47 patients (32 male and 15 female; age range, 21–85 years; median age, 65 years) who had suspected renal lesions on abdominal CT underwent MRI for further evaluation and characterisation of the lesions from April 2005 to August 2007 in our university hospital. A region of interest was drawn around the tumour area on apparent diffusion coefficient (ADC) maps. Final diagnosis was confirmed by histological examination of surgical specimens from all patients. The ADC value was significantly higher in renal cell carcinoma (RCC) than in transitional cell carcinoma (2.71±2.35 × 10⁻³ mm² s⁻¹ vs 1.61±0.80 × 10⁻³ mm² s⁻¹; p = 0.022). While analysing the histological subtypes of RCC, a significant difference in ADC values between clear cell carcinoma and non-clear cell carcinoma was found (1.59±0.55 × 10⁻³ mm² s⁻¹ vs 6.72±1.85 × 10⁻³ mm² s⁻¹; p = 0.0004). Similarly, ADC values of RCC revealed a significant difference between positive and negative metastatic lesions (1.06±0.38 × 10⁻³ mm² s⁻¹ vs 3.02±2.44 × 10⁻³ mm² s⁻¹; p = 0.0004), whereas intensity on T₁ and T₂ weighted imaging did not reach statistical significance. In conclusion, DWI has clinical value in the characterisation of renal carcinomas and could be applied in clinical practice for their management.Renal cell carcinoma (RCC) is the most common primary malignant tumour of the kidney; it accounts for 2–3% of all adult cancers and is the sixth cause of death by tumour throughout the world. More than 80% of renal cancers that arise in the renal parenchyma are RCC, whereas the majority of renal pelvis cancers are transitional cell carcinomas (TCCs) [1–3]. The three most common subtypes of RCC are (i) clear cell carcinoma, one of the most common types, accounting for 70–80% of cases; (ii) papillary renal cell carcinoma, accounting for about 10–15% of cases; and (iii) chromophobe renal carcinoma, which is the least common, accounting for 5% of all RCCs. The annual rate of RCC diagnosis is increasing as a result of incidental detection by cross-sectional abdominal imaging of patients with suspected abdominal disorders. Increased detection rates carry a favourable prognosis; however, mortality from RCC has not decreased [2–4].Diffusion-weighted imaging (DWI) is frequently used in cranial MRI studies and has shown potential for the characterisation of lesions such as acute cerebral infarctions, intracranial tumours, various infectious diseases and metabolic disorders [5–8]. The role of DWI is limited outside the central nervous system, owing to its inherent extreme sensitivity to motion, such as that related to respiration, peristalsis and artefacts, thus resulting in a high signal to noise ratio. With the development of advanced MR technology and the use of faster robust sequences, better quality has been obtained in abdominal imaging [9]. DWI with high b-values has been reported to have a high sensitivity for depicting malignant disease. Apparent diffusion coefficient (ADC) values of malignant hepatic, ovarian, breast, prostatic, colonic and uterine cervical tumours were lower than those of benign lesions or normal tissue [10–18].Previous studies have suggested that patients with chromophobe and papillary RCC have a better prognosis than patients with clear cell RCC [19]. Accurate characterisation of patients with renal masses is essential to ensure appropriate clinical management, staging and prognosis. The clinical utility of ADC values in kidney disease has been reported: a higher value of ADC was noted in simple renal cysts and renal pelvis of hydronephrotic kidney, whereas a lower value was noted in solid renal tumours and kidneys with chronic and acute renal failure [9, 20–22]. The role of the ADC value in characterising the histological subtypes of renal carcinoma is limited [3, 9]. Therefore, the present study aimed to evaluate the role of DWI in combination with T₁ and T₂ weighted MRI for the differential diagnosis and characterisation of renal carcinoma.     

Cross-sectional area measurement of the coronary arteries using CT angiography at the level of the bifurcation: is there a relationship?

PURPOSE

Our aim was to determine whether there is a correlation between cross-sectional areas of the left main coronary artery (LMCA), left anterior descending artery (LAD), and circumflex artery (CX) in normal cases using coronary CT angiography.

METHOD

Examinations of 180 patients (119 men and 61 women) were selected among 2248 consecutive coronary CT angiography studies. Cross-sectional areas of LMCA, LAD, and CX were measured at the level of bifurcation. Correlation between age, height, and body mass index and coronary artery cross-sectional areas was investigated and possibility of formulating a correlation between the cross-sectional areas of LMCA, LAD, and CX was explored.

RESULTS

Mean cross-sectional areas of LMCA, LAD, and CX were found as 17.4±3.9 mm², 12.5±3.1 mm², and 10.5±3.0 mm², respectively. While cross-sectional areas of LMCA and LAD were significantly larger in men, no significant difference was found between the sectional areas of CX in men and women. A multiple regression analysis was conducted to elucidate the relationship between the cross-sectional areas of LMCA LAD, and CX. Our analysis showed that the relationship between LMCA, LAD, and CX cross-sectional areas can be formulated as follows: LMCA=3.870 + 0.718×LAD + 0.434×CX.

CONCLUSION

There is a correlation between the cross-sectional areas of LMCA, LAD, and CX at the level of bifurcation, and this correlation can be expressed with a formula.Coronary artery disease is the leading cause of death worldwide. Thus, coronary artery imaging is one of the most commonly used diagnostic methods. Recently, coronary computed tomography angiography (CCTA) has become another widely used method in coronary artery imaging since it is a noninvasive technique that is easy to perform (1, 2).One of the major advantages of CCTA is that it allows for the measurement of not only two-dimensional diameters but also cross-sectional areas of the vascular structures. Thus, it is possible to calculate the degree of narrowing caused by atherosclerotic plaques in case of obstruction. It is also possible to predict the symptoms that may arise in a patient in relation to the obstruction and determine the treatment that can be performed using CT angiography.Atherosclerotic plaques are commonly seen adjacent to vascular bifurcations (3, 4). Left main coronary artery (LMCA) length is variable, and it is shorter in comparison with other main coronary arteries. Therefore, atherosclerotic plaques can occupy the whole vessel in some cases. In such cases, it is difficult to determine the degree of narrowing caused by the plaque since it is not possible to understand the reference artery diameter. Similarly, normal dimensions of the arteries might not be understood in cases of plaque build-up that occupy the long segment starting from the left anterior descending artery (LAD) and circumflex artery (CX) origin. Recently developed multidetector computed tomography (MDCT) technology provides valuable information in terms of understanding three-dimensional anatomy of coronary bifurcation and measuring the angle and vessel cross-sectional area (5, 6). This information is considerably important for the diagnosis and treatment of bifurcation lesions.Some studies aimed to elucidate the correlation between the diameters of coronary arteries at bifurcation levels using Murray’s law or Finet’s formula (7, 8). However, no study aiming to evaluate the relationship between the cross-sectional areas of the coronary arteries at the level of LMCA bifurcation is found to date. In this study, we aimed to investigate whether there is a correlation between LMCA, CX, and LAD cross-sectional areas in normal cases and explore the possibility of explaining the relationship with a formula, which may then be used to estimate the reference cross-sectional area of a stenosed coronary artery when the other two arteries are normal.     

Assessment of early treatment response after CT-guided radiofrequency ablation of unresectable lung tumours by diffusion-weighted MRI: a pilot study

The aim of this study was to evaluate prospectively the early treatment response after CT-guided radiofrequency ablation (RFA) of unresectable lung tumours by MRI including diffusion-weighted imaging (DWI). The study protocol was approved by the ethics committee of our hospital and signed consent was obtained from each patient. We studied 17 patients with 20 lung lesions (13 men and 4 women; mean age, 69±9.8 years; mean tumour size, 20.8±9.0 mm) who underwent RFA using a LeVeen electrode between November 2006 and January 2008. MRI was performed on a 1.5T unit before and 3 days after ablation. We compared changes in the apparent diffusion coefficient (ADC) on DWI and response evaluation based on subsequent follow-up CT. 14 of the 20 treatment sessions showed no local progression on follow-up CT, whereas 6 treatment sessions showed local progression (range, 3–17 months; mean, 6 months). For the no-progression group, the ADC pre- and post-RFA were 1.15±0.31 × 10⁻³ mm² s⁻¹ and 1.49±0.24 × 10⁻³ mm² s⁻¹, respectively, while the respective ADC values for those that showed local progression were 1.05±0.27 × 10⁻³ mm² s⁻¹ and 1.24±0.20 × 10⁻³ mm² s⁻¹. The ADC of the ablated lesion was significantly higher than before the procedure (p<0.05). There was a significant difference in the ADC post-RFA between no-progression and local progression groups (p<0.05). Our prospective pilot study showed that the ADC without local progression was significantly higher than with local progression after RFA, suggesting that the ADC can predict the response to RFA for lung tumours.After the first report in 2000 [1], lung radiofrequency ablation (RFA) is now considered effective in the treatment of lung cancer, which is traditionally considered unresectable owing to compromised pulmonary function or advanced age. In general, complications associated with lung RFA are minimal, and favourable local control has been reported in a number of studies of tumours with a diameter of 30 mm or less [1–5]. However, only a limited number of studies have been published regarding the treatment outcome after lung RFA [6–10]. In this process, a layer of normal lung tissue surrounding the tumour is also ablated as a safety margin. Inevitably, the ablated lesion depicted on a CT scan immediately after the procedure is larger than the original tumour mass. However, this region of increased density shrinks with time, but follow-up CT may still show the ablated lesion being as big as, or larger than, the tumour size before the procedure [6, 7]. Thus, radiologists sometimes encounter difficulty in distinguishing scarred tissue from a tumour residue/local progression when the size of the lesion remains the same. Accurate assessment of RFA outcome would have important consequences, as recurrent tumours can be treated again if detected at an early stage. Different modalities of early-stage follow-up examination, such as contrast-enhanced CT [8] and fluorodeoxyglucose positron emission tomography (FDG–PET), have been of great interest and their usefulness has been reported by several groups [9, 10]. Another approach — MR diffusion-weighted imaging (DWI) — which is based on the measurement of motion of water molecules, has also been reported as a non-invasive evaluation modality [11–19]. In this method, the apparent diffusion coefficient (ADC) represents the water content and distribution, the cellular density and the cell membrane integrity, suggesting the potential usefulness of an ADC map for estimating tumour viability. Indeed, DWI has been successfully used to assess the efficacy of radiotherapy [11, 12], chemotherapy [13–15] and transcatheter arterial embolisation [16, 17]. To our knowledge, only two studies have reported the use of DWI to evaluate the therapeutic outcome of RFA [18, 19]. A previous study reported that the ADC value of an ablated rabbit tumour model (VX2 tumour) was significantly higher than that of untreated tumours, and that FDG uptake on micro-PET for small animals with ablated tumours was significantly lower than for untreated tumours. These results indicate that DWI at 2 days and FDG–PET at 3 days after RFA are both potentially feasible modalities for monitoring the early effects of the procedure [19]. In this study, we calculated the ADC in tumour lesions before and after clinical lung RFA and examined the usefulness of DWI in the early detection of tumour response to RFA.     

Contribution of real-time elastography in diagnosis of polycystic ovary syndrome

PURPOSE

We aimed to assess the feasibility and reproducibility of real-time elastography (RTE) for displaying the effects of morphological changes in the ovary in polycystic ovary syndrome (PCOS).

METHODS

Forty-eight patients diagnosed with PCOS and 48 healthy women were enrolled in the study. Ultrasonography and RTE were performed on the 3^rd day of the menstrual cycle. Evaluations were performed independently by two radiologists. Ovarian volume, number of follicles, elasticity pattern, and strain ratio were measured. Elasticity patterns were assessed as hard (type 1; blue or blue-green), moderate (type 2; green or green-yellow) or soft (type 3; red or orange-red).

RESULTS

Both radiologists determined the elasticity pattern as mostly type 1 in the PCOS group and type 3 in the control group (P < 0.01). The mean strain ratios obtained by the first and second radiologist were 6.1±1.8 (2.7–10.1) and 6.0±1.5 (3.0–9.0) in PCOS and 3.3±1.2 (1.7–7.2) and 3.2±0.9 (1.7–6.8) in the control group, respectively (P < 0.001). Interobserver agreement was moderate for the elasticity pattern (κ=0.48) and good for the strain ratio (intraclass correlation coefficient, 0.77). A strain ratio of 3.8 was determined as the optimized cutoff point by receiver operating curve analysis. Strain ratio was correlated with the ovarian volume and the number of detected follicles (P < 0.001).

CONCLUSION

Elasticity pattern and strain ratio can help identify morphological changes that make PCOS ovaries stiffer than normal ovaries.In reproductive-aged women, polycystic ovary syndrome (PCOS) is an important cause of infertility and is characterized by menstrual irregularities, hirsutism and signs of hyperandrogenism, and polycystic ovary appearance (1–3). In addition to insulin resistance, serum androgenic hormone levels are increased, causing undesired effects on women’s metabolic, reproductive, and cardiovascular health (1–5). PCOS is characterized by enlarged ovaries containing small cysts, for which the syndrome was named (6).Real-time elastography (RTE) is a novel and dynamic imaging technique that is simply based on the hardness or softness of tissues or organs under the appropriate compression and can be used with conventional ultrasonography (US) probes after performing gray-scale and Doppler US. Displacement of soft tissues is greater than hard tissues, and tissue hardness is displayed as a color-coded image that lays over the gray-scale US image translucently (7). Elastography has been used previously for differentiation of pathologies of tissues and organs, such as thyroid, breast, kidneys, and liver (7–9). There are limited studies about the elastographic properties of the ovaries, mostly focused on ovarian neoplasms and, to the best of our knowledge, there is no medical data concerning the elasticity properties of the ovary in PCOS (10, 11). In this study, our purpose was to assess the feasibility and reproducibility of RTE for displaying the effects of morphological changes in the ovary in PCOS and to put forward the value of RTE as a new diagnostic approach for diagnosing PCOS.     

Diffusion-weighted MRI as a potential imaging biomarker reflecting the metastatic potential of upper urinary tract cancer

Objective:

To evaluate the role of diffusion-weighted MRI (DW-MRI) as an imaging biomarker for upper urinary tract cancer (UUTC) that has already metastasized or will metastasize soon.

Methods:

61 patients clinically diagnosed with UUTC were prospectively enrolled in this study. All the patients underwent MRI, including DW-MRI, prior to any interventions. Correlations between apparent diffusion coefficient (ADC) and other clinicopathological variables, including metastasis-free survival, were analysed.

Results:

Median follow-up period was 938 days. Of the 61 patients, 12 had any metastases at the initial diagnosis. 11 patients developed metastases during the follow-up period. These 23 patients were categorized as “Metastatic”. Of the remaining 38 patients, 35 with a follow-up period longer than 400 days were categorized as “Localized”. ADC was significantly lower in the Metastatic category than in the Localized (p = 0.0002) category. Multivariate analysis of pre-operative variables identified ADC (cut-off value, 1.08 × 10⁻³ mm² s⁻¹) and clinical T stage based on T₂ weighted MRI as an independent predictive factor of metastatic UUTC. 46 patients without any metastases during the initial diagnosis were stratified into a high-risk group (16 patients with low ADC and clinical T3–4) and a low-risk group (30 patients with high ADC or clinical Ta-2). The 3-year metastasis-free survivals were 45% and 93%, respectively.

Conclusion:

In the current study, UUTC with lower ADC value is more likely to have metastatic potential. Incorporating ADC with clinical T stage helps to differentiate metastatic UUTC at the initial diagnosis.

Advances in knowledge:

DW-MRI is a potential imaging biomarker reflecting metastatic propensity of UUTC.Upper urinary tract cancer (UUTC) is a potentially lethal disease. The prognosis remains poor even when standard care, radical nephroureterectomy (RNU) is performed, and almost one-third of the patients die within 5 years.^1–3 In the management of localized UUTC, adjuvant chemotherapy has no impact on survival, particularly owing to the impaired post-surgical renal function or comorbidity.⁴ However, neoadjuvant chemotherapy, which showed a survival benefit in bladder cancer,⁵ may have a similar benefit in UUTC.Neoadjuvant chemotherapy can be considered an option for locally advanced disease at diagnosis. Two nomograms are available for predicting locally advanced UUTC in the pre-operative setting: one includes tumour histological grade, architecture and location and the other includes histological grade and radiological clinical stage.^6,7 “Localized disease” at the initial diagnosis that will develop metastasis soon after RNU can also be a candidate for neoadjuvant chemotherapy. However, identifying these occult or developing metastases pre-operatively remains a challenge.Diffusion-weighted MRI (DW-MRI) is a functional imaging technique that reveals physiological information by quantifying the diffusion of water molecules in tissues.⁸ The extent of water diffusion is quantified as the apparent diffusion coefficient (ADC). In 2009, a consensus meeting was held on the use of DW-MRI as a cancer imaging biomarker.⁹ An extraordinary opportunity for DW-MRI to evolve into a clinically valuable imaging tool was indicated. This imaging technique has been incorporated into general oncological imaging practices, including tissue characterization, monitoring the treatment response and predicting treatment outcome, in various cancers.^8,10–14Previous studies demonstrated the role of the ADC as a marker for the biological aggressiveness of UUTC by showing a correlation of the ADC with the histological grade and the Ki-67 labelling index.^14,15 Furthermore, the ADC was significantly associated with the cancer-specific survival after RNU.¹⁵ Therefore, we hypothesized that the ADC can be used as a marker to reflect the metastatic potential of UUTC, as has been reported in bladder cancer.¹⁶ The aim of this study is to show that the ADC can predict UUTC that has already metastasized or will metastasize soon. We first evaluated ADC values of the biologically metastatic UUTC and non-metastatic UUTC. Secondarily, we analysed the potential of the ADC to predict the development of metastasis.     

Radioembolization with yttrium-90 resin microspheres for neuroendocrine tumor liver metastases

PURPOSE

We aimed to evaluate the effectiveness and safety of radioembolization with yttrium-90 (⁹⁰Y) microspheres in cases with unresectable neuroendocrine tumor liver metastases (NETLMs).

METHODS

Thirty patients (mean age, 55 years) underwent resin-based ⁹⁰Y radioembolization for unresectable NETLM at a single institution between April 2008 and June 2013. Post-treatment tumor response was assessed by cross-sectional imaging using the Response Evaluation Criteria in Solid Tumors (RECIST). Prognostic variables that affected survival were determined.

RESULTS

The mean follow-up was 23.0±19.4 months and the median overall survival was 39 months (95% CI, 12.6–65.4 months), with one- and two-year survival rates of 71% and 45%, respectively. Imaging follow-up using RECIST at three-month intervals demonstrated partial response in 43%, complete remission in 3%, stable disease in 37%, and progressive disease in 17% of patients. Extent of tumor involvement was found to have a statistically significant influence on overall survival (P = 0.03). The existence of extrahepatic disease at the time of radioembolization, radiographic response, age, and primary neuroendocrine tumor site were not significant prognostic factors.

CONCLUSION

The current study demonstrates the effectiveness and safety of radioembolization for the treatment of unresectable NETLMs. We identified that the extent of tumor involvement has a significant effect on overall survival. The use of imaging methods reflecting metabolic activity or cellularity such as scintigraphy or diffusion-weighted MRI would be more appropriate, for the response evaluation of liver metastases after radioembolization.Neuroendocrine tumors (NETs) are a heterogenous group of slow-growing and hormon-releasing malignant tumors. Even though primary NETs originate from a number of locations, 40%–70% of all carcinoids arise in the small intestine and appendix (1, 2). The most common site for metastasis is the liver. Neuroendocrine tumor liver metastasis (NETLM) results in hormone-secretion-related symptoms leading to carcinoid syndrome, pressure on structures, or liver replacement (1–4). Patients with liver metastasis have a five-year survival rate of less than 20% (5). Over the years, improvements in local treatments yielded better control of the symptoms and survival rates, yet only 10% of the patients have limited illness and are eligible for surgery (6). Patient symptomatology and survival can be improved by transarterial treatments like embolization and chemoembolization (6). Limitations of these techniques include the short duration of the effects and the controversial approaches regarding the optimal timing and sequence of the procedures due to the variability of tumor progression (7, 8). Long-term survival benefit was not achieved with systemic chemotherapy (9–11) and treatment with somatostatin analogues is mostly associated with symptomatic relief; there is no clear knowledge of their effect on survival of patients who have carcinoid tumor and metastasis (12).Selective internal radiation therapy (SIRT) has been used to treat unresectable primary and secondary liver cancers for over a decade. Yttrium-90 (⁹⁰Y) is a pure high-energy β emitter with a mean tissue penetration of 2.5 mm. The radioactive microspheres prefer tumoral vascular distribution, so that normal liver tissue is relatively spared and high doses are directed to the tumoral tissue (13). Also, radioembolization-related acute and subacute toxicities are seemingly more tolerable than the ones related to other hepatic embolization procedures (14–16). In this study, we aimed to evaluate the effectiveness and safety of ⁹⁰Y microspheres in cases with unresectable NETLMs.     

Renal diffusion-weighted imaging in diabetic nephropathy: correlation with clinical stages of disease

PURPOSE

We aimed to assess the correlation between renal apparent diffusion coefficient (ADC) values measured by diffusion-weighted imaging (DWI) and the clinical stages of diabetic nephropathy.

MATERIALS AND METHODS

DWI (b value, 0 and 600 s/mm²) was performed in 78 patients with clinically confirmed diabetic nephropathy (study group) and 22 volunteers without diabetes mellitus or any renal disease (control group). The mean ADCs were calculated from multiple region-of-interest circles positioned in the renal cortex. Diabetic nephropathy was clinically categorized into five stages based on the values of urinary albumin excretion and glomerular filtration rate (GFR).

RESULTS

Mean renal ADC values of patients with stage 3 or 4 disease were significantly lower than those in patients with stage 1 or 2 disease and the control group (P < 0.001). ADC values of patients with stage 5 disease were significantly lower than those in patients with stage 4 (P = 0.003), stage 3 (P = 0.020), stages 2 and 1, and the control group (P < 0.001). Significant correlations were found between mean renal ADC values and clinical stages of diabetic nephropathy (r=−0.751, P < 0.001), between mean renal ADC values and estimated GFR values (r=0.642, P < 0.001), and between mean renal ADC values and urinary albumin excretion (r=−0.419, P < 0.001).

CONCLUSION

Renal ADC values show a significant correlation with clinical stages of diabetic nephropathy. As a relatively simple and noninvasive tool without contrast media administration, renal quantitative DWI may potentially play a role in making clinical decisions in the follow-up of diabetic patients.Diabetic nephropathy is classically defined as a clinical syndrome characterized by persistent albuminuria, a relentless decline in glomerular filtration rate (GFR) progressing to end-stage renal disease, raised arterial blood pressure, and enhanced cardiovascular morbidity and mortality (1). In diabetic patients, renal functional deterioration is the result of heterogeneous renal structural changes, including glomerular basal membrane thickening and mesangial expansion, extracellular matrix accumulation, mesangiolysis, reduced podocyte number, microaneurysm formation, arteriolar hyalinosis which ultimately leads to glomerulosclerosis, tubular atrophy, interstitial expansion, and fibrosis (2). Renal damage occurs in multiple stages. Throughout its early stages, diabetic nephropathy has no symptoms. Persistent microalbuminuria is a predictor of the development of clinical nephropathy. Microalbuminuria has been proposed as a marker of widespread endothelial dysfunction and indicates microvascular damage (3). Better understanding of the mechanisms that lead to structural and functional changes in the diabetic kidney may facilitate the development of more effective follow-up and treatment modalities. Diagnostic tests that help identify early microvascular damage at an early stage will provide significant benefits to get the disease under control. Quantitative diffusion-weighted magnetic resonance imaging (MRI) may offer this opportunity and can play a role in the evaluation of renal disease. Several studies have indicated the potential use of the apparent diffusion coefficient (ADC) as a marker of renal function, showing lower renal ADC in kidney dysfunction (4–9). Yet, there are only a few studies concerning the use of renal quantitative diffusion-weighted imaging (DWI) in diabetic nephropathy (5, 9–11). In this study, our aim was to assess the correlation between renal ADC values from quantitative DWI of kidneys and the clinical stages of nephropathy in diabetic patients.     

Therapeutic effects of transarterial infusion of lipiodol and ethanol in various ratios in a rabbit VX2 tumor model

PUSRPOSE

We aimed to evaluate the therapeutic effect and safety of transcatheter arterial embolization with various volume ratios of lipiodol and ethanol in a rabbit VX2 tumor model to identify the optimal volume ratio.

METHODS

Eighteen adult male New Zealand white rabbits implanted with VX2 tumors in their left liver lobes were randomly divided into six groups based on volume ratios of lipiodol to ethanol: group A, 3:1; group B, 2:1; group C, 1:1; group D, 1:2; group E, 1:3; and group F, 1:4. Pre- and post-treatment unenhanced magnetic resonance imaging was used to detect tumor formation and evaluate tumor growth rates. Liver samples were harvested one week after the procedure, and apoptosis index of tumor tissues was evaluated by pathologic examination and TUNEL assay.

RESULTS

Tumor size decreased in groups B, C, and D, but increased in groups A, E, and F. Tumor growth rates in groups A–F were 0.40±0.03, −0.11±0.21, −0.08±0.09, −0.12±0.07, 0.06±0.12, and 0.05±0.09, respectively. The change in tumor size was significantly different in group A compared with the rest of the groups, but no significant difference was observed among groups B–F. Apoptosis indexes of the six groups were 4.7±2.1%, 6.7±2.1%, 11.7±3.1%, 11.0±2.0%, 10.7±3.2%, and 12±3%, respectively. Apoptosis index was significantly lower in group A compared with groups C–F (P < 0.05). Apoptosis index of group B was significantly lower than groups C and F. There was no significant difference among the other groups.

CONCLUSION

The volume ratios of lipiodol to ethanol ranging from 2:1 to 1:4 were equally effective, the ratios 2:1 and 1:3 had equal safety, and the ratios 1:1 and 1:2 indicated better long-term therapeutic effect. Increasing ethanol in the mixture caused more severe liver injury. Optimal efficacy and safety was achieved with a lipiodol to ethanol volume ratio of 1:1.Hepatocellular carcinoma (HCC) is one of the most common solid malignancies in the world (1). Transarterial chemoembolization (TACE) is widely used to treat HCC patients who are not suitable candidates for curative treatments (2–5). The most common embolic agent used in TACE is lipiodol, which can be mixed with surgical glues (cyanoacrylates) or with ethanol for interventional procedures. Ethanol was confirmed to be effective in occluding the hepatic arterial system, but it can cause perisinusoidal fibrosis (6). Transarterial ethanol ablation (TEA) with a mixture of lipiodol-ethanol has been shown to be an effective treatment for HCC (7). Yu et al. (8) reported that the embolization efficacy and treatment effectiveness of TEA were probably superior to those of TACE for HCC, and a decreased proportion of ethanol (33% by volume) in the mixture was suggested. Lipiodol-ethanol mixtures with reduced ethanol proportions have been shown to be associated with decreased endothelial damage while maintaining effective delivery of the mixtures to tumor vasculature (9). However, the optimal ratio between lipiodol and ethanol that should be used for TEA remains controversial.In the present study, we aimed to determine the efficacy and optimum volume ratio of lipiodol-ethanol mixture in a rabbit VX2 hepatoma model.     

Added value of diffusion-weighted MRI in detection of cervical cancer recurrence: comparison with morphologic and dynamic contrast-enhanced MRI sequences

PURPOSE

We aimed to evaluate the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) for detecting post-treatment cervical cancer recurrence. The detection accuracy of T2-weighted (T2W) images was compared with that of T2W MRI combined with either dynamic contrast-enhanced (DCE) MRI or DWI.

METHODS

Thirty-eight women with clinically suspected uterine cervical cancer recurrence more than six months after treatment completion were examined with 1.5 Tesla MRI including T2W, DCE, and DWI sequences. Disease was confirmed histologically and correlated with MRI findings. The diagnostic performance of T2W imaging and its combination with either DCE or DWI were analyzed. Sensitivity, positive predictive value, and accuracy were calculated.

RESULTS

Thirty-six women had histologically proven recurrence. The accuracy for recurrence detection was 80% with T2W/DCE MRI and 92.1% with T2W/DWI. The addition of DCE sequences did not significantly improve the diagnostic ability of T2W imaging, and this sequence combination misclassified two patients as falsely positive and seven as falsely negative. The T2W/DWI combination revealed a positive predictive value of 100% and only three false negatives.

CONCLUSION

The addition of DWI to T2W sequences considerably improved the diagnostic ability of MRI. Our results support the inclusion of DWI in the initial MRI protocol for the detection of cervical cancer recurrence, leaving DCE sequences as an option for uncertain cases.Cervical cancer is the fourth most frequent cancer in women worldwide (1). Early stage disease is treated with surgery or chemoradiotherapy and has a good prognosis. However, around 30% of all patients treated for cervical carcinoma develop progressive or recurrent tumors (2).Recurrent cervical cancer is defined as local tumor regrowth or the development of distant organ/lymph node metastases at least six months after regression of the initial lesion. Approximately two-thirds of recurrences appear within the first two years following initial treatment, with 90% recurring by five years post-treatment (3). Risk factors for recurrence include histopathologic features, depth of tumor invasion, and nodal status (4).Pelvic recurrence can be located centrally (cervix, uterus, vagina, parametria, ovaries, bladder, or rectum) or in the pelvic sidewalls. Extrapelvic recurrence most commonly involves the para-aortic lymph nodes, lungs, liver, or bone (4–6).Treatment of recurrent cancer depends on the primary treatment approach, location, and extension. Patients with locally recurrent disease can be offered salvage treatments with curative potential (chemoradiotherapy, if not given previously, or pelvic exenteration in patients who already received chemoradiotherapy). Distant metastases, however, are nearly always incurable (3).In patients who successfully completed primary treatment, surveillance has been advocated to detect the residual or recurrent disease at curable stages (7). The use of imaging studies such as magnetic resonance imaging (MRI) is indicated on the basis of clinical suspicion (8).T2-weighted (T2W) imaging is the reference sequence for cervical cancer staging (9). Recurrent tumors are known to show high signal intensity on T2W MRI, contrasting with the low signal intensity of the cervical stroma. However, some benign conditions such as necrosis, inflammation, and edema may also increase signal intensity on T2W images, representing a potential challenge to the radiologist, particularly after radiotherapy (10–13).Moreover, post-treatment changes can result in areas of fibrosis that are also difficult to differentiate from recurrence (14). MRI has proven to be superior to computed tomography (CT) in distinguishing fibrosis and scarring from active disease, but imaging findings are sometimes indeterminate, complicating the evaluation of recurrent disease (3).In recent years, the functional MRI techniques such as dynamic multiphase contrast-enhanced (DCE) MRI and diffusion-weighted imaging (DWI) have emerged as fundamental tools in female pelvic imaging evaluation (15). Although DCE was shown to be more accurate than T2W alone for tumor recurrence identification, the use of both sequences is recommended (10).Recently, DWI has been added to pelvic MRI protocols to increase diagnostic accuracy in tumor staging. This technique is a functional tool that relies on tissue water displacement to create a contrasted image. For correct evaluation and avoidance of pitfalls, the generated images must be interpreted alongside anatomical sequences. The apparent diffusion coefficient (ADC) map is also needed to reduce image misinterpretation, for example due to the T2 shine-through effect (15). In highly cellular tissues, water movement is restricted and such lesions appear bright at high b-values (1000 s/mm²) and have low ADC value, appearing dark gray on ADC maps in contrast to areas of freely moving water such as urine in the bladder (14). Some recent studies have suggested that DWI and ADC maps can be potentially useful in oncologic follow-up (14, 16).The purpose of this study was to compare the accuracy of T2W/DWI with that of conventional anatomical sequences alone and T2W/DCE imaging sequences in the evaluation of recurrent disease in patients treated for uterine cervical carcinoma.     

Single-stage endovascular treatment in patients with severe extracranial large vessel stenosis and concomitant ipsilateral unruptured intracranial aneurysm

PURPOSE

We aimed to evaluate the safety and effectiveness of single-stage endovascular treatment in patients with severe extracranial large vessel stenosis and concomitant ipsilateral unruptured intracranial aneurysm.

METHODS

Hospital database was screened for patients who underwent single-stage endovascular treatment between February 2008 and June 2013 and seven patients were identified. The procedures included unilateral carotid artery stenting (CAS) (n=4), bilateral CAS (n=2), and proximal left subclavian artery stenting (n=1) along with ipsilateral intracranial aneurysm treatment (n=7). The mean internal carotid artery stenosis was 81.6% (range, 70%–95%), and the subclavian artery stenosis was 90%. All aneurysms were unruptured. The mean aneurysm diameter was 7.7 mm (range, 5–13 mm). The aneurysms were ipsilateral to the internal carotid artery stenosis (internal carotid artery aneurysm) in five patients, and in the anterior communicating artery in one patient. The patient with subclavian artery stenosis had a fenestration aneurysm in the proximal basilar artery. Stenting of the extracranial large vessel stenosis was performed before aneurysm treatment in all patients. In two patients who underwent bilateral CAS, the contralateral carotid artery stenosis, which had no aneurysm distally, was treated initially.

RESULTS

There were no procedure-related complications or technical failure. The mean clinical follow-up period was 18 months (range, 9–34 months). One patient who underwent unilateral CAS experienced contralateral transient ischemic attack during the clinical follow-up. There was no restenosis on six-month follow-up angiograms, and all aneurysms were adequately occluded.

CONCLUSION

A single-stage procedure appears to be feasible for treatment of patients with severe extracranial large vessel stenosis and concomitant ipsilateral intracranial aneurysm.The concomitance of severe extracranial large vessel stenosis and unruptured ipsilateral distal intracranial aneurysm is often detected incidentally and their management is not clear (1). Although there are many studies in the literature that report different treatment approaches, there is no definite consensus on the management of the concomitant lesions (2–14). Various treatment options have been suggested, such as initial treatment of the aneurysm before revascularization of the stenosis, treating both lesions in the same surgical session and correcting the stenosis without treating the aneurysm (1, 5, 6, 9–11, 14–16). Few studies have reported single-stage endovascular treatment of both lesions as an effective method (17–19). On the other hand, the treatment of each lesion by this technique may lead to procedure-related undesired events such as cerebral ischemia/stroke or aneurysm rupture.In this study, we aimed to present the radiologic and clinical results of seven consecutive patients who underwent single-stage endovascular treatment of severe extracranial large vessel stenosis and concomitant unruptured ipsilateral intracranial aneurysm and discuss the safety and feasibility of this approach. In addition, distinct from the limited number of similar studies in the literature, we present our experience with bilateral carotid artery stenting (CAS) and proximal subclavian artery stenting during single-stage endovascular treatment.