Diffusion-weighted MR imaging of thyroid nodules

Introduction  The purpose of our study was to determine the diagnostic role of diffusion-weighted imaging (DWI) in the differentiating of malignant and benign thyroid nodules by using fine needle aspiration biopsy cytology criteria as a reference standard. The apparent diffusion coefficient (ADC) values of the normal-looking thyroid parenchyma were also evaluated both in normal patients and in patients with nodules. Methods  Between March 2007 and February 2008, 76 consecutive patients with ultrasound-diagnosed thyroid nodules and 20 healthy subjects underwent diffusion-weighted MR imaging by using single-shot spin echo, echo planar imaging. A total of 93 nodules were included in the study using the following b factors 100, 200, and 300 mm²/s. ADC values of thyroid nodules and normal area in all subjects were calculated and compared using suitable statistical analysis. Results  Mean ADC values for malignant and benign nodules were and for b-100 factor, and for b-200, and and , for b-300, respectively. Mean ADC values of malignant nodules were lower than benign nodules. There were significant differences in ADC values between benign and malignant nodules. ADC values among normal-appearing thyroid parenchyma of patients and normal-appearing thyroid parenchyma of healthy subjects were insignificant at all b factors. Conclusion  Benign nodules have higher ADC values than malignant ones. DWI may be helpful in differentiating malign and benign thyroid nodules.     

Correlation of FDG-PET findings with histopathology in the assessment of response to induction chemoradiotherapy in non-small cell lung cancer

Purpose The objective of this study was to evaluate the ability of FDG-PET to predict the response of primary tumour and nodal disease to preoperative induction chemoradiotherapy in patients with non-small cell lung cancer (NSCLC).Methods FDG-PET studies were performed before and after completion of chemoradiotherapy prior to surgery in 26 patients with NSCLC. FDG-PET imaging was performed at 1 h (early) and 2 h (delayed) after injection. Semi-quantitative analysis was performed using the standardised uptake value (SUV) at the primary tumour. Percent change was calculated according to the following equation: . Based on histopathological analysis of the specimens obtained at surgery, patients were classified as pathological responders or pathological non-responders. The clinical nodal stage on the post-chemoradiotherapy PET scan was visually determined and compared with the final pathological stage.Results Eighteen patients were found to be pathological responders and eight to be pathological non-responders. SUV_after values from both early and delayed images in pathological responders were significantly lower than those in pathological non-responders. The percent change values from early and delayed images in the pathological responders were significantly higher than those in the pathological non-responders. The post-chemoradiotherapy PET scan accurately predicted nodal stage in 22 of 26 patients.Conclusion FDG-PET may have the potential to predict response to induction chemoradiotherapy in patients with NSCLC.     

A contrast-oriented algorithm for FDG-PET-based delineation of tumour volumes for the radiotherapy of lung cancer: derivation from phantom measurements and validation in patient data

Purpose  An easily applicable algorithm for the FDG-PET-based delineation of tumour volumes for the radiotherapy of lung cancer was developed by phantom measurements and validated in patient data. Methods  PET scans were performed (ECAT-ART tomograph) on two cylindrical phantoms (phan1, phan2) containing glass spheres of different volumes (7.4–258 ml) which were filled with identical FDG concentrations. Gradually increasing the activity of the fillable background, signal-to-background ratios from 33:1 to 2.5:1 were realised. The mean standardised uptake value (SUV) of the region-of-interest (ROI) surrounded by a 70% isocontour (mSUV₇₀) was used to represent the FDG accumulation of each sphere (or tumour). Image contrast was defined as: where BG is the mean background − SUV. For the spheres of phan1, the threshold SUVs (TS) best matching the known sphere volumes were determined. A regression function representing the relationship between TS/(mSUV₇₀ − BG) and C was calculated and used for delineation of the spheres in phan2 and the gross tumour volumes (GTVs) of eight primary lung tumours. These GTVs were compared to those defined using CT. Results  The relationship between TS/(mSUV₇₀ − BG) and C is best described by an inverse regression function which can be converted to the linear relationship . Using this algorithm, the volumes delineated in phan2 differed by only −0.4 to +0.7 mm in radius from the true ones, whilst the PET-GTVs differed by only −0.7 to +1.2 mm compared with the values determined by CT. Conclusion  By the contrast-oriented algorithm presented in this study, a PET-based delineation of GTVs for primary tumours of lung cancer patients is feasible.     

[<Superscript>99m</Superscript>Tc]Demotensin 5 and 6 in the NTS1-R-targeted imaging of tumours: synthesis and preclinical results

Purpose The aim of this study was to evaluate the applicability of [^99mTc]Demotensin 5 and 6 in the targeted diagnostic imaging of neurotensin subtype 1 receptor (NTS1-R)-expressing tumours. Methods Labelling of Demotensin 5 and 6 with ^99mTc was conducted by brief incubation with ^99mTcO₄ ⁻, SnCl₂ and citrate anions in alkaline medium at ambient temperature. Affinities of conjugates for the NTS1-R were determined by competition binding experiments in WiDr cell membranes using [¹²⁵I-Tyr³]NT as the radioligand. Saturation binding assays were conducted for [^99mTc/^99gTc]Demotensin 6 in WiDr cell membranes. Internalisation of [^99mTc]Demotensin 5 and 6 was studied at 37°C in WiDr cells. Biodistribution of [^99mTc]Demotensin 5 and 6 was performed in female Swiss nu/nu mice bearing human WiDr xenografts. Results Unlabelled conjugates showed a high affinity for the human NTS1-R (Demotensin 5 IC₅₀=0.03±0.01 nM; Demotensin 6 IC₅₀=0.08±0.02 nM), while high affinity was also exhibited by (radio)metallated [^99mTc/^99gTc]Demotensin 6 (K _d=0.13±0.01 nM). [^99mTc]Demotensin 5 and 6 internalised rapidly and specifically in WiDr cells. After injection in WiDr tumour-bearing mice, radiopeptides, and especially the doubly stabilised [^99mTc]Demotensin 6, showed NTS1-R-mediated uptake in the intestines and in the implanted tumour (4.30±0.45%ID/g at 1 h post injection) and rapid renal excretion from non-target tissues into the urine. Conclusion [^99mTc]Demotensin 6 shows a favourable preclinical profile and further testing in patients is warranted to monitor its eventual applicability as a radiotracer in the diagnostic imaging of NTS1-R-positive tumours.     

Monitoring the neoadjuvant therapy response in gynecological cancer patients using FDG PET

Purpose We retrospectively evaluated the ability of FDG PET to predict the response of primary tumor to chemotherapy or chemoradiotherapy in patients with gynecological cancer. Methods FDG PET examinations were performed before and after completion of chemotherapy or chemoradiotherapy in 21 patients with advanced gynecological cancer (uterine cancer, n = 13; ovarian cancer, n = 8). PET imaging was performed at 1 h after injection. Semi-quantitative analysis was performed using the standardized uptake value (SUV) at the primary tumor for both before and after therapy (SUV_before and SUV_after, respectively). Percent change value was calculated according to the following equation: . Based on histopathological analysis of the specimens obtained at surgery, patients were classified as responders or non-responders. Results Ten patients were found to be responders and 11 to be non-responders. SUV_after in responders was significantly lower than that in non-responders (p < 0.005). Taking an arbitrary SUV_after of 3.8 as the cutoff for differentiating between responders and non-responders, FDG PET showed a sensitivity of 90%, a specificity of 63.6%, and an accuracy of 76.2%. The percent change value in the responders was significantly higher than that in the non-responders (p < 0.0005). Taking an arbitrary percent change of 65 as the cutoff for differentiating between responders and non-responders, FDG PET showed a sensitivity of 90%, a specificity of 81.8%, and an accuracy of 85.7%. Conclusion These findings suggest that FDG PET-derived parameters including SUV and especially percent change value may have the potential to predict response to chemotherapy or chemoradiotherapy in patients with advanced gynecological cancer.     

<Superscript>68</Superscript>Ga-DOTANOC: biodistribution and dosimetry in patients affected by neuroendocrine tumors

Objectives The aim of this work was the evaluation of biodistribution and radiation dosimetry of ⁶⁸Ga-DOTANOC in patients affected by neuroendocrine tumors. Materials and methods We enrolled nine patients (six male and three female) affected by different types of neuroendocrine tumors (NETs). Each patient underwent four whole body positron emission tomography (PET) scans, respectively, at 5, 20, 60, and 120 min after the intravenous injection of about 185 MBq of ⁶⁸Ga-DOTANOC. Blood and urine samples were taken at different time points post injection: respectively, at about 5, 18, 40, 60, and 120 min for blood and every 40–50 min from injection time up to 4 h for urine. The organs involved in the dosimetric evaluations were liver, heart, spleen, kidneys, lungs, pituitary gland, and urinary bladder. Dosimetric evaluations were done using the OLINDA/EXM 1.0 software. Results A physiological uptake of ⁶⁸Ga-DOTANOC was seen in all patients in the pituitary gland, the spleen, the liver, and the urinary tract (kidneys and urinary bladder). Organs with the highest absorbed doses were kidneys . The mean effective dose equivalent (EDE) was . Discussion and conclusions The excretion of the compound was principally via urine, giving dose to the kidney and the urinary bladder wall. As SSTR2 is the most frequently expressed somatostatin receptor and ⁶⁸Ga-DOTANOC has high affinity to it, this compound might play an important role in PET oncology in the future. The dosimetric evaluation carried out by our team demonstrated that ⁶⁸Ga-DOTANOC delivers a dose to organs comparable to, and even lower than, analogous diagnostic compounds.     

Detection of relevant colonic neoplasms with PET/CT: promising accuracy with minimal CT dose and a standardised PET cut-off

Objective:

To determine the performance of FDG-PET/CT in the detection of relevant colorectal neoplasms (adenomas ≥10 mm, with high-grade dysplasia, cancer) in relation to CT dose and contrast administration and to find a PET cut-off.

Methods:

84 patients, who underwent PET/CT and colonoscopy (n?=?79)/sigmoidoscopy (n?=?5) for ${\left( {{\hbox{79}} \times {\hbox{6}} + {\hbox{5}} \times {\hbox{2}}} \right)} = {\hbox{484}}$ colonic segments, were included in a retrospective study. The accuracy of low-dose PET/CT in detecting mass-positive segments was evaluated by ROC analysis by two blinded independent reviewers relative to contrast-enhanced PET/CT. On a per-lesion basis characteristic PET values were tested as cut-offs.

Results:

Low-dose PET/CT and contrast-enhanced PET/CT provide similar accuracies (area under the curve for the average ROC ratings 0.925 vs. 0.929, respectively). PET demonstrated all carcinomas (n?=?23) and 83% (30/36) of relevant adenomas. In all carcinomas and adenomas with high-grade dysplasia (n?=?10) the SUV_max was ≥5. This cut-off resulted in a better per-segment sensitivity and negative predictive value (NPV) than the average PET/CT reviews (sensitivity: 89% vs. 82%; NPV: 99% vs. 98%). All other tested cut-offs were inferior to the SUV_max.

Conclusion:

FDG-PET/CT provides promising accuracy for colorectal mass detection. Low dose and lack of iodine contrast in the CT component do not impact the accuracy. The PET cut-off SUV_max?≥?5 improves the accuracy.     

99mTc-MIBI pinhole SPECT in primary hyperparathyroidism: comparison with conventional SPECT, planar scintigraphy and ultrasonography

Purpose A pinhole collimator is routinely used to increase the resolution of scintigraphy. This prospective study was conducted to determine the interest of ^99mTc-MIBI pinhole single-photon emission computed tomography (SPECT) for the preoperative localisation of parathyroid lesions in primary hyperparathyroidism. Methods All patients underwent a neck ultrasonography (US), and ^99mTc-MIBI planar images and two consecutive SPECT with a parallel (C-SPECT) and a pinhole collimator (P-SPECT). P-SPECT was performed with a tilted detector equipped with a pinhole collimator and reconstructed with a dedicated OSEM algorithm. A diagnostic confidence score (CS) was assigned to each procedure considering intensity and extra-thyroidal location of suspected lesions: 0 = negative, 1 = doubtful, 2 = moderately positive, 3 = positive. The results of these preoperative localisation studies were compared with surgical, pathological and 6-month biological findings. Results Fifty-one patients cured after surgery were included. Surgery revealed 55 lesions (median weight 0.5 g, 11 in ectopy). Sensitivities of US, planar imaging, C-SPECT and P-SPECT were, respectively, 51, 76, 82 and 87%. Nine glands were only detected by tomography and five glands only by P-SPECT. planar scans and P-SPECT were complementary and, when combined together, showed the highest sensitivity (93%). Compared with planar imaging and C-SPECT, P-SPECT increased CS for 42 and 53% of lesions, respectively, and contributed to markedly reduce the number of uncertain results. Conclusions A combination of planar scintigraphy and P-SPECT appears to be a highly accurate preoperative imaging procedure in primary hyperparathyroidism.     

Differentiation of malignant and benign pulmonary nodules with first-pass dual-input perfusion CT

Objective

To assess diagnostic performance of dual-input CT perfusion for distinguishing malignant from benign solitary pulmonary nodules (SPNs).

Methods

Fifty-six consecutive subjects with SPNs underwent contrast-enhanced 320-row multidetector dynamic volume CT. The dual-input maximum slope CT perfusion analysis was employed to calculate the pulmonary flow (PF), bronchial flow (BF), and perfusion index $ \left( {\mathrm{PI},={{\mathrm{PF}} \left/ {{\left( {\mathrm{PF} + \mathrm{BF}} \right)}} \right.}} \right) $ . Differences in perfusion parameters between malignant and benign tumours were assessed with histopathological diagnosis as the gold standard. Diagnostic value of the perfusion parameters was calculated using the receiver-operating characteristic (ROC) curve analysis.

Results

Amongst 56 SPNs, statistically significant differences in all three perfusion parameters were revealed between malignant and benign tumours. The PI demonstrated the biggest difference between malignancy and benignancy: 0.30?±?0.07 vs. 0.51?±?0.13 , P?<?0.001. The area under the PI ROC curve was 0.92, the largest of the three perfusion parameters, producing a sensitivity of 0.95, specificity of 0.83, positive likelihood ratio (+LR) of 5.59, and negative likelihood ratio (?LR) of 0.06 in identifying malignancy.

Conclusions

The PI derived from the dual-input maximum slope CT perfusion analysis is a valuable biomarker for identifying malignancy in SPNs. PI may be potentially useful for lung cancer treatment planning and forecasting the therapeutic effect of radiotherapy treatment.

Key Points

? Modern CT equipment offers assessment of vascular parameters of solitary pulmonary nodules (SPNs) ? Dual vascular supply was investigated to differentiate malignant from benign SPNs. ? Different dual vascular supply patterns were found in malignant and benign SPNs. ? The perfusion index is a useful biomarker for differentiate malignancy from benignancy.     

Brain-core temperature of patients before and after orthotopic liver transplantation assessed by DWI thermometry

Purpose

To assess brain-core temperature of end-stage liver disease patients undergoing orthotopic liver transplantation (OLT) using a temperature measurement technique based on the apparent diffusion coefficient of the cerebrospinal fluid in the lateral ventricles.

Materials and methods

The study group was composed of 19 patients with a model for end-stage liver disease (MELD) score of 23.7 who underwent MR imaging before and after OLT. MR imaging studies were performed with a 1.5T MR scanner. Brain-core temperature (T: °C) was calculated using the following equation from the apparent diffusion coefficient (D) of the cerebrospinal fluid in the lateral ventricles: \(T = {{2256.74} \mathord{\left/ {\vphantom {{2256.74} {\ln \left( {4.39221/D} \right)}}} \right. \kern-0pt} {\ln \left( {4.39221/D} \right)}}{-}273.15\) measured with a DWI sequence (b value 1000 s/mm²). We compared brain-core temperature of all patients before and after OLT.

Results

Brain-core temperature measurements were successfully taken in all patients before and after OLT. The measured brain-core temperature mean?±?standard deviation was 38.67?±?1.76 °C before OLT and 38.60?±?0.99 °C after OLT, showing no significant difference (P = 0.643).

Conclusions

Brain-core temperature was stable in patients undergoing OLT. DWI thermometry may provide a supplementary brain biomarker to confirm that cerebral blood flow and metabolism are stable in patients undergoing OLT.

     

Real-time ultrasound elastography: an assessment of enlarged cervical lymph nodes

Objectives

To determine the efficacy of real-time elastography (RTE), compared with our previously proposed prediction model, in the detection of malignancy in cervical lymph nodes (LNs).

Methods

One hundred and thirty-one patients underwent ultrasound-guided fine needle aspiration biopsy (ultrasound FNAB) after ultrasound and RTE evaluation. The formula of the RTE scoring system was a four-point visual scale, based on a previously determined model. The formula of the prediction model was: $ 0.06\times \left( {\mathrm{age}} \right)+4.76\times \left( {{{{\mathrm{short}-\mathrm{axis}}} \left/ {{\mathrm{long}-\mathrm{axis}\;\mathrm{ratio}}} \right.}} \right)+2.15\times \left( {\mathrm{internal}\;\mathrm{echo}} \right)+1.80\times \left( {\mathrm{vascular}\;\mathrm{pattern}} \right) $ . An extended model was constructed with four previous predictors and elasticity scores, using a logistic regression model.

Results

Final histology revealed 77 benign and 54 malignant LNs. In the elasticity score system, sensitivity was 66.7 %, specificity was 57.1 %, the positive predictive value (PPV) was 52.2 % and the negative predictive value (NPV) was 71.0 %. In the prediction model system, sensitivity was 79.6 %, specificity was 92.2 %, the PPV was 87.8 % and the NPV was 86.6 %. When the extended and the original model were compared, the areas under the receiver operating characteristic curve (c-statistic) was 0.94 and 0.95, respectively (P?>?0.05).

Conclusions

Qualitative RTE offers no additional value over conventional ultrasound in predicting malignancy in cervical LNs.

Key Points

? An ultrasound system can help in the assessment of cervical lymph nodes. ? Grey-scale and power Doppler ultrasound remain fundamental for neck nodal evaluation. ? Qualitative real-time elastography provided no additional value compared with current prediction models.     

Contribution of the positron camera to studies of regional lung structure and function

Positron emission tomography is a major technological advance in the characterisation of structure-function relationships within and between regions in normal and abnormal lungs (Hughes et al. 1985). The measurements are noninvasive and relatively exact since the geometric conditions are precisely defined. Regional expansion, flow (ventilation, perfusion), oxygen concentration (from \({{\dot V_{\text{A}} } \mathord{\left/ {\vphantom {{\dot V_{\text{A}} } {\dot Q}}} \right. \kern-\nulldelimiterspace} {\dot Q}}\)) and glucose metabolism can be measured in absolute terms per cubic centimetre of thorax or per gram of extravascular lung. Examples of structure-function relationships in normal subjects, emphysema, bronchitis and sarcoidosis are briefly presented.

     

Wie zuverlässig ist die Kaliumbestimmung im Glaskörperinhalt als Mittel zur Todeszeitschätzung?

Zusammenfassung Die Ergebnisse der 10 zu diesem Thema vorliegenden Arbeiten werden kurz referiert. Sodann wurden 419 in der Literatur angegebene Kaliumwerte bekannter Leichenzeit nach der von Krauseu. Mitarb. vorgeschlagenen Formel zur Ermittlung der Zeit post mortem umgerechnet. Die Diskrepanz zwischen erwarteten und gefundenen Zeitwerten ist aber nicht geringer als die aus der Literatur auch sonst zu entnehmende Streuung der Beziehung Kaliumwert/Todeszeit. Als etwas enger erwies sich die nach Krauseu. Mitarb. berechnete Relation , aber auch deren Streuung ist für die Erfordernisse einer Todeszeit-bestimmung zu groß.

---

Summary The results of the 10 contributions, hitherto published on this subject, are summarized in short. Tentatively, 419 potassium values with known time after death contained in the literature, were calculated by means of a formula derived from Krauseet al. (1971). Discrepancies between expected and calculated hours post mortem, however, were no less than the deviations between potassium values and time after death already known from the literature. Although the relation between potassium values and the radix of hour post mortem, according to Krauseet al., proved indeed to be more satisfactory, deviations are too great for a reliable estimation of the time after death.

Herrn Prof. Dr. B. Mueller zum 75. Geburtstag gewidmet.     

A method to quantitate cerebral blood flow using a rotating gamma camera and iodine-123 iodoamphetamine with one blood sampling

A method has been developed to quantitate regional cerebral blood blow (rCBF) using iodine-123-labelled N-isopropyl-p-iodoamphetamine (IMP). This technique requires only two single-photon emission tomography (SPET) scans and one blood sample. Based on a two-compartment model, radioactivity concentrations in the brain for each scan time (early: t _e ; delayed: td) aredescribed as: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa% aaleaacaWG0baabeaakmaabmaabaGaamiDamaaBaaaleaacaWGLbaa% beaaaOGaayjkaiaawMcaaiabg2da9iaadAgacqWIpM+zcaWGdbWaaS% baaSqaaiaadggaaeqaaOWaaeWaaeaacaWG0bWaaSbaaSqaaiaadwga% aeqaaaGccaGLOaGaayzkaaGaey4LIqSaamyzamaalaaabaGaamOzaa% qaaiaadAfadaWgaaWcbaGaamizaaqabaaaaOGaamiDamaaBaaaleaa% caWGLbaabeaaaaa!4D64!\[C_t \left( {t_e } \right) = fC_a \left( {t_e } \right) \otimes e\frac{f}{{V_d }}t_e \] and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa% aaleaacaWG0baabeaakmaabmaabaGaamiDamaaBaaaleaacaWGKbaa% beaaaOGaayjkaiaawMcaaiabg2da9iaadAgacqWIpM+zcaWGdbWaaS% baaSqaaiaadggaaeqaaOWaaeWaaeaacaWG0bWaaSbaaSqaaiaadsga% aeqaaaGccaGLOaGaayzkaaGaey4LIqSaamyzamaalaaabaGaamOzaa% qaaiaadAfadaWgaaWcbaGaamizaaqabaaaaOGaamiDamaaBaaaleaa% caWGKbaabeaaaaa!4D61!\[C_t \left( {t_d } \right) = fC_a \left( {t_d } \right) \otimes e\frac{f}{{V_d }}t_d \] respectively, where denotes the convolution integral; C _a (t), the arterial input function; f rCBF; and V _d , the regional distribution volume of IMP. Calculation of the ratio of the above two equations and a table look-up procedure yield a unique pair of rCBF and V _d for each region of interest (ROI). A standard input function has been generated by combining the input functions from 12 independent studies prior to this work to avoid frequent arterial blood sampling, and one blood sample is taken at 10 min following IMP administration for calibration of the standard arterial input function. This calibration time was determined such that the integration of the first 40 min of the calibrated, combined input function agreed best with those from 12 individual input functions (the difference was 5.3% on average). This method was applied to eight subjects (two normals and six patients with cerebral infarction), and yielded rCBF values which agreed well with those obtained by a positron emission tomography H₂ ¹⁵O autoradiography method. This method was also found to provide rCBF values that were consistent with those obtained by the non-linear least squares fitting technique and those obtained by conventional microsphere model analysis. The optimum SPET scan times were found to be 40 and 180 min for the early and delayed scans, respectively. These scan times allow the use of a conventional rotating gamma camera for clinical purposes. V _d values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring V _d for each ROI. In conclusion, optimization of the blood sampling time and the scanning time enabled quantitative measurement of rCBF with two SPET scans and one blood sample.     

Predictive value of [<Superscript>18</Superscript>F]-fluoride PET for monitoring bone remodeling in patients with orthopedic conditions treated with a Taylor spatial frame

Purpose

The Taylor Spatial Frame (TSF) is used to correct orthopedic conditions such as correction osteotomies in delayed fracture healing and pseudarthrosis. Long-term TSF-treatments are common and may lead to complications. Current conventional radiological methods are often unsatisfactory for therapy monitoring. Hence, an imaging technique capable of quantifying bone healing progression would be advantageous.

Methods

A cohort of 24 patients with different orthopedic conditions, pseudarthrosis (n?=?10), deformities subjected to correction osteotomy (n?=?9), and fracture (n?=?5) underwent dynamic [¹⁸F]-fluoride (Na¹⁸F) PET/CT at 8 weeks and 4 months, respectively, after application of a TSF. Parametric images, corresponding to the net transport rate of [¹⁸F]-fluoride from plasma to bone, K _i were calculated. The ratio of the maximum K _i at PET scan 2 and 1 (\( {\overline{K}}_{i, \max } \)) as well as the ratio of the maximum Standard Uptake Value at PET scan 2 and 1 (\( {\overline{SUV}}_{\max } \)) were calculated for each individual. Different treatment end-points were scored, and the overall treatment outcome score was compared with the osteoblastic activity progression as scored with \( {\overline{K}}_{i, \max } \) or \( {\overline{SUV}}_{\max } \).

Results

\( {\overline{K}}_{i, \max } \) and \( {\overline{SUV}}_{\max } \) were not correlated within each orthopedic group (p?>?0.1 for all groups), nor for the pooled population (p?=?0.12). The distribution of \( {\overline{K}}_{i, \max } \) was found significantly different among the different orthopedic groups (p?=?0.0046) -also for \( {\overline{SUV}}_{\max } \) (p?=?0.022). The positive and negative treatment predictive values for \( {\overline{K}}_{i, \max } \) were 66.7 % and 77.8 %, respectively. Corresponding values for \( {\overline{SUV}}_{\max } \) were 25 % and 33.3 %

Conclusions

The \( {\overline{K}}_{i, \max } \) obtained from dynamic [¹⁸F]-fluoride-PET imaging is a promising predictive factor to evaluate changes in bone healing in response to TSF treatment.

     

Age estimation in children by measurement of open apices in teeth: an Indian formula

The aim of this paper is twofold: first, to evaluate an Indian sample by Cameriere’s European formula; and second, if this formula turns out to be unsuitable, to study a specific formula for Indian children. Orthopantomographs taken from 480 Indian children (227 girls and 253 boys) aged between 3 and 15 years were analyzed. Following the pilot study, subjects’ age was modeled as a function of gender (g), region of country (C), and morphological variables (predictors: x ₅, the distance between the inner sides of the open apex of the second premolar divided by the tooth length; s = x₁ + x₂ + x₃ + x₄ + x₅ + x₆ + x₇ s = x_{1} + x_{2} + x_{3} + x_{4} + x_{5} + x_{6} + x_{7} , sum of normalized open apices; N _0, the number of teeth with root development complete. Results showed that all these variables except gender and second premolar contributed significantly to the fit so that all were included in the regression model, yielding the following linear regression formula:

No difference in plantar flexion maximal exercise power output between men and women

Background

Maximal oxygen consumption \( \dot{V}O_{{2{\text{MAX}}}} \) can be lower in women compared to men during traditional, systemic exercise even when corrected for differences in fat free mass (FFM). One potential source for lower \( \dot{V}{\text{O}}_{{2{\text{MAX}}}} \) might be inherent differences in muscle in men and women. Exercising isolated muscle such as plantar flexion provides the opportunity to study muscle function independent of systemic O₂ delivery limitations. It was hypothesized that women would have lower plantar flexion power output (PO) than men even when corrected to calf FFM.

Methods

Maximum \( \dot{V}{\text{O}}_{2} \) and PO were measured during graded treadmill exercise and PO during plantar flexion exercise in men and women.

Results

During maximal treadmill exercise, men had greater absolute \( \dot{V}{\text{O}}_{2} \) and PO. When expressed relative to FFM, there was no difference in PO at maximum between sexes, but \( \dot{V}{\text{O}}_{{2{\text{MAX}}}} \) was still greater in men. During maximal plantar flexion exercise, men demonstrated greater absolute PO, but this difference between sexes was eliminated when PO was expressed relative to calf FFM.

Conclusion

Healthy women do not demonstrate inherently lower muscle PO. Lower maximal \( \dot{V}{\text{O}}_{2} \) per FFM measured during treadmill exercise in women than men appears due to factors other than differences in muscle aerobic capacity.

     

An IGRT margin concept for pelvic lymph nodes in high-risk prostate cancer

Purpose

Gold-marker-based image-guided radiation therapy (IGRT) of the prostate allows to correct for inter- and intrafraction motion and therefore to safely reduce margins for the prostate planning target volume (PTV). However, pelvic PTVs, when coadministered in a single plan (registered to gold markers [GM]), require reassessment of the margin concept since prostate movement is independent from the pelvic bony anatomy to which the lymphatics are usually referenced to.

Methods

We have therefore revisited prostate translational movement relative to the bony anatomy to obtain adequate margins for the pelvic PTVs compensating mismatch resulting from referencing pelvic target volumes to GMs in the prostate. Prostate movement was analyzed in a set of 28 patients (25 fractions each, totaling in 684 fractions) and the required margins calculated for the pelvic PTVs according to Van Herk’s margin formula \(M=2.5\Upsigma +1.64\left (\sigma^{\prime}-\sigma _{p}\right )\).

Results

The overall mean prostate movement relative to bony anatomy was 0.9 ± 3.1, 0.6 ± 3.4, and 0.0 ± 0.7?mm in anterior/posterior (A/P), inferior/superior (I/S) and left/right (L/R) direction, respectively. Calculated margins to compensate for the resulting mismatch to bony anatomy were 9/9/2?mm in A/P, I/S, and L/R direction and 10/11/6?mm if an additional residual error of 2?mm was assumed.

Conclusion

GM-based IGRT for pelvic PTVs is feasible if margins are adapted accordingly. Margins could be reduced further if systematic errors which are introduced during the planning CT were eliminated.

     

Determination of intestinal radiocalcium absorption by double tracer method with 85Sr i.v.

The intestinal absorption of radiocalcium can be estimated on the basis of serum radioactivity after an oral administration of ⁴⁷Ca (o.S(t)) and intravenous application of ⁸⁵Sr. High linear correlation (r=0.94) between the true absorption of ⁴⁷Ca and the absorption calculated from radioactivity of serum, was found in 42 subjects. The true absorption of ⁴⁷Ca was estimated by following up serum and faeces radioactivity during 7 days after oral administration of radiocalcium. Results of the radiocalcium absorption rate for a group of control subjects are also presented. The radiocalcium absorption rate (i(x)) is calculated by means of the following integral: $$\int\limits_{\text{0}}^H {i(x)dx = \frac{{\sin (IIb)}}{{II}}} (100/S_{1{\text{Ca}}} )\int\limits_{\text{0}}^H {{\text{o}}{\text{.S}}} (t)(H - t)^{b - 1} dt.$$ In order to solve this integral one should know numerical values of constants b and S _1Ca which determine the serum specific activity after i.v. application of ⁴⁷Ca, according to the power function: $${\text{i}}{\text{.v}}{\text{. }}S(t) = S_{{\text{ }}1{\text{Ca}}} t^{ - b} $$ The numerical value of the constant b can be estimated by following serum radioactivity o.S(t) between 6 and 24 h after an oral administration of ⁴⁷Ca. Because of the high linear correlation between the S ₁ constants obtained by ⁴⁷Ca and that obtained by ⁸⁵Sr, the value of the S _1Ca constant was estimated by following serum radioactivity of ⁸⁵Sr given intravenously. Determination of ⁴⁷Ca intestinal absorption by double-tracer technique with ⁸⁵Sr i.v. is quick and accurate.